cerc - annual report 1999 - chalmers · 3 cerc – annual report 1999 preface over the past five...

CERC – Annual Report 19991

C E RC

Chalmers University of Technology

Combustion Engine Research Center

AnnualReport

1999

CERC – Annual Report 1999 2

CERCCombustion Engine Research Center

Table of Contents

General background

Summary of the fourth year – 1999

Cooperation with Industry

Project agreementsAgreements with other companiesCooperation with industr y

Scientific results and future outlook

Studies of flame propagation,quenching, and hydrocarbonafter-burning in lean highlyturbulent mixtures

The ef fect of fuel preparation onthe operational characteristicsof a direct injection engine anddeposit formation

Torque sensors for engineapplications

Applied combustion diagnostics

Laser diagnostics of dense sprays

Modeling of spray formation,ignition and combustion ininternal combustion engines

Influence of cavitation and hydraulicflip on spray formation, ignition delay,combustion and pollutant formation

Control of fuel/air ratio in the pre-chamber of a lean-burn gas-engine byuse of ionization measurements

Direct injected two-stroke engine

On-board manufactured ethersas an ignition improver foralcohol engines

Human resources

Management of CERCStaf f associated with CERC

Finances duringthe period 1998 -2000

References

The cover

Droplet and gas temperaturedistribution for a simulated injectionof a methanol and di -methyl -etherfuel composition after 2.138 ms.

General BackgroundThe center was founded on November 1, 1995, by a decision ofthe Board of Chalmers University of Technology, and was based ona three-party agreement signed by the Swedish Board for Technicaland Industrial Development (NUTEK), Chalmers University ofTechnology and five Swedish industrial companies, Husqvarna AB,SAAB Automobile AB, Scania CV AB, Volvo Car Corporation andVolvo Truck Corporation. The agreement regulated the interactionsamong the three parties with respect to financial commitment,scientific goals and the use of research results.

During the present period (1997-2001) the coordination has beentransferred to the Swedish National Energy Administrationand ABB Industrial Systems AB, Statoil A.S., Mecel AB, AspenPetroleum AB, Volvo Penta AB and Wärtsilä NSD Sweden AB havebecome full members in the center.

The center has been defined as one of twenty-eight CompetenceCenters in Sweden of long-term importance for the Swedishindustry. The center is assumed to be a forum where joint industrialand academic research can be performed. The purpose is to buildup a concentrated interdisciplinary research pool in which theparticipting companies can actively take part in and benefit in along-term perspective. The activities at the center, named CERC(Combustion Engine Research Center), have initially beenconcentrated on the mobilization of a platform for research in thearea associated with internal combustion engine technology.

The long-term objectives of the center are to carry out fundamentalresearch of high industrial interest, focused on the Otto- and Dieselprocesses and to transfer knowledge between the academiccommunity and the Industrial members in an interdisciplinary way.Specifications of strategically important research areas have beenperformed by scientists at Chalmers University of Technology incooperation with representatives from industry.The research has been focused on projects in both basic andapplied research.

The center is governed by a board consisting of three membersfrom the academic community and five members from theparticipating companies.

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Preface

Over the past five years, many of the world’s leading vehicle manufacturersas well as manufacturers of chain saws, power cutters an so on havedeveloped a variety of engine models for the future market and researchrelated to internal combustion engines has been recognized as strategic forthe Swedish industry. The integration of important elements in the research,using advanced forms of mathematical modeling and engine technology,will be a natural platform when enhancing the long-term competitivenessof the industry in an economical as well as an environmental and sustainableperspective.

The activities at the CERC have primarily been focused on research areasassociated with spray diagnostics and modeling which offers manyopportunities for interdisciplinary cooperation between departments atChalmers University of Technology as well as between departments at otheruniversities both nationally and internationally.

So far, efforts have been to put on strengthening the infrastructure inareas relevant to combustion engine technology and several good resultshave been achieved since the departments have understood the significanceof the co-ordination initiatives taken by the CERC. However, to achieveforefront results, the cooperation between different scientific disciplineshas to be emphasized even further. This requires a cross -disciplinaryapproach which also combines new knowledge of applied mathematics,fluid dynamics control synthesis and environmental engineering. The keyissues are fundamental studies of the dynamics of both chemical and physicalprocesses, including chemical kinetics, thermodynamics, the transport ofmass, heat and momentum as well as control of the combustion processes.

As this is my last year as director for CERC, I would like to express my thanksto all collaborators and supporters and I wish CERC all succes in the future.

Anders KarlströmDirector of CERC


Project agreements

During the run-in period, agreem-ents for the projects have beensigned by the depar tmentsinvolved. The texts have beenprepared in consultation withthe par ticipating companies andinvolve specifications concerningactive par ties, a plan for theproject, project leader, thecomposition of the groups ofexper ts assisting the projectleader, financial suppor t andthe par ticipating scientists’commitments and responsibilities.

Agreements with new companies

Several companies have shownan interest in par ticipating in theactivities in CERC, and newagreements between ChalmersUniversity of Technology on the onehand and ABB Industrial SystemsAB, Statoil A.S., Mecel AB, AspenPetroleum AB, Volvo Penta AB ochWär tsilä NSD Sweden AB on theother, have been signed.

Finally, a new agreement betweenChalmers University of Technologyand AVL LIST GmbH has beensigned concerning researchcooperation regarding fluid flowand combustion modelling.

Summary

The Center of Excellence in Internal Combustion Engines (CombustionEngine Research Center – CERC) was formally established on November 1,1995 and inaugurated on March 26, 1996.

The center organizes and conducts research and development within thefield of internal combustion engines in collaboration with industrialcompanies, university departments and other research centers in Europe.The center’s vision is to be an internationally prominent center focusing onlong-term industrial needs. Specifically, research associated with significantreductions in both fuel consumption and engine emissions from gasoline anddiesel engines will be prioritized. This will call for a combination of inter-disciplinary engine, fuel and emission research. To realise this vision, severalprojects have focused on spray formation, spray diagnostics, flamepropagation studies and alternative fuel concepts of different types.

During the period, efforts have been made to establish an interdisciplinarynetwork in which both academic and industrial scientists can come togetherand discuss the appropriate orientation for the proposed research. Originally,three departments were primarily involved in the process of creating thecenter. At the present time, joint ventures with four departments in engine-related research can be defined, in which financial support has been obtainedfrom both internal and external interests.

The current international working contacts within the CERC’s activities, tomention but a few, involve participation in the FIRE code development withAVL LIST GmbH (Austria) to improve spray and premixed combustionmodeling, as well as chemistry treatment. Another project involves thedevelopment of a modified spray rig version for Chalmers University ofTechnology, based on the RWTH Aachen high-pressure combustionequipment.

The member companies of the CERC comprise all the engine manufacturersin Sweden and, during the run-in period, other companies with complemen-tary skills and expertise within the research field have also been members.

Cooperation with IndustryAll our research areas are interdisciplinary in character, which requires, goodcooperation between different research disciplines within the University.Moreover, the interaction between the University and the companies hasbeen vital for the follow-up of the activities. This can be seen in the fact thatthe most of the projects have been accomplished in collaboration with thecompanies. Important projects have been defined aiming to broaden andmake better use of existing but not necessarily commercial measurement andmodelling techniques. The knowledge obtained in these projects is ofinterest when defining the subsequent projects within the applied field bothin the company laboratories and the laboratories at the University.

During the run-in period, the projects were specified by three preparationgroups consisting of scientists associated with the University and thecompanies. These groups serve as guiding body for the board and meet twicea year or when needed. Furthermore, expert groups have been formalizedwithin each project and consist of both scientists and representatives fromindustry. The aim of these groups is to assist the project leaders. Thesegroups are called by the project leader when the need arises.


Most of the activities were initiated during the spring of 1996 and have nowreached the stage at which significant results can be presented [ 61,62,63].

Even though there might appear to be segregated projects, it becomes clear, afterstudying the project content more closely, that research associated with spray formationand spray diagnostics has been primarily prioritized, as a result of which many projectsinteract and thereby in some sense create a program area. This concentration has beenimportant during the establishment stage and a number of future project concepts willbe created and hived off as project proposals during the next term of the agreement.Descriptions of the project results are given in summary form below.

Scientific resultsand future outlook

Studies of Flame Propagation, Quenching, and HydrocarbonAfter-burning in Lean Highly Turbulent Mixtures

Jercy Chomiak, Professor

Andrei Lipatnikov, Senior researcher

Johan Wallensten, PhD Student

The aim of the project is to study, both theoreti-cally and experimentally, the critical areas of lean,high-turbulence combustion in a well defined,simple case.

During 1999, the theoretical studies have beenfocused on further development of turbulentFlame Speed Closure (FSC) model developed inthe project and on the comparison of the FSCwith other approaches.

The main results are as follows.

1) A self-similar regime of premixed turbulentflame development has been characterized[1,2]. Although this regime is of particular im-portance for SI engine combustion, its predic-tion is the insurmountable challenge for manycurrent numerical models. However, the FSCis well tailored for modeling this regime.

2) Modeling of pressure-dependence of turbulentflame speed has been analyzed and clarified [3].

3) Based on numerical simulations, it has beenshown that both flame quenching by strongturbulence and turbulent flame speed devel-opment are substantially affected by the flamegeometry and more pronounced for statisti-cally spherical flames as compared with the

statistically planar ones [4-7]. These new resultsfurther validate the FSC model and extend therange of its applicability. Based on these find-ings, a new method of experimental evaluationof fully developed turbulent flame speed hasbeen proposed to be used [4,5,7]. Other physi-cal mechanisms important for modeling highlyturbulent combustion are discussed in [8].

4) The FSC model looks like a model based onthe standard gradient transport, whereas coun-ter-gradient transport is well known to occurin turbulent flames. To resolve this apparentcontradiction, theoretical and numerical stud-ies of the problem have been performed[1,2,4]. The results show that for SI engine con-ditions, counter-gradient transport is sup-pressed by transient [1] and geometrical effects[1,4]. Moreover, it is of secondary importanceas compared to the mean heat release rate [2]and may be neglected to the leading order. Thisconclusion further validates the model andextends the range of it applicability.

5) Effects of turbulence length scale on flamespeed have been analyzed and clarified [9].

6) Numerical simulations of laminar flames havebeen continued in order to create a data baseof physico-chemical characteristics of combus-tible mixtures, which should be specified asinitial conditions in input files in order to usethe modified FIRE code with the FSC model.

7) Further numerical studies of the modified codehave been performed [10].

The experimental facility for premixed flamestudies was redesigned to allow flat flame stud-ies.

Figure 1. The cubic combustion vessel forstudies of turbulent flame propagation. Hereit is equipped with 16 spark plugs in thebottom wall to create a planar flame.

Figure 2. Simulation of combustion inthe combustion vessel shows theformation of a planar flame.


The Effect of Fuel Preparation on the Operational Characteristicsof a Direct Injection Engine and Deposit Formation

Ingemar Denbratt, Professor

Håkan Sandquist, PhD student

Stratified charge direct injection spark ignitionengines have attracted considerable interest inrecent years and most car manufacturers are work-ing intensively in this field. The reasons for thereawakened interest are the potential improve-ments in fuel economy, torque and power outputas well as improved cold start, warm-up and tran-sient operation. There is a potential, at low speedsand loads, to reduce the fuel consumption by 20- 25% over homogeneous stoichiometric opera-tion. The reduction in fuel consumption comesfrom reduced heat and exhaust losses, due to alower temperature in the cylinder during the com-bustion and expansion strokes and to the elimi-nation of the pumping work. The ratio of specificheats is more favourable due to a higher ratio of2-atomic molecules which also increases the effi-ciency.

To obtain a stratified charge the fuel must beinjected shortly before the time of ignition, hencethe need for direct injection. Ideally, the mixturearound the spark plug should be stoichiometricor slightly rich, while the rest of the combustionchamber should be filled with pure air or air di-luted with recycled combustion products. Theoperation of a stratified charge SI engine relieson the production of this close to stoichiometricmixture in the spark plug region. The mixturepreparation depends on spray characteristics, in-cylinder flow field, spray/wall interactions, fuelproperties, temperature and pressure.

There are two principal ways of forming astratified charge: to stabilize the spray by geometri-cal means (wall guided systems) or to use the in-

cylinder flow pattern (air guided systems). Wallguided systems are by far the most common inengine development today. Examples of wallguided systems are the Mitsubishi GDI and ToyotaD4 production engines. Spray impingement on thepiston seems unavoidable, and this is a problemfor all stratified charge systems, but especially forthe wall guided ones.

Due to the short time available for mixturepreparation, the distillation curve of the fuel islikely to have a greater impact on the operatingcharacteristics of a direct injection stratifiedcharge engine than on those of conventional SIengines. A single component fuel can not modelthe evaporation of a full boiling range gasoline,but provides information about hydrocarbonemission formation mechanisms. Consequentlyfull boiling range gasolines are compared withsingle component fuels in our studies.

The main problems with stratified charge en-gines are high HC emissions (more than twicethose of conventional SI engines), soot emissions,and catalytic converter operation due to low ex-haust temperatures and high oxygen content inthe exhaust. So far it has been impossible to reachthe theoretical 20 - 25% reduction in fuel con-sumption. Although contemporary engines havereached fuel consumption reductions of between10 and 15% on the European driving cycle, atpresent they do not meet the most stringent emis-sions legislation.

The sources of hydrocarbon (HC) emissionshave been studied in the single cylinder GDI en-gine, and published in three papers. The HC emis-

Figure 3. Mass flow of exhaust and HCemissions, and HC concentration trace.


sions were studied using a fast flame ionizationdetector (fast FID). In the first paper, [11], a com-parison of homogeneous and stratified chargeoperation is made, and the results show higherHC but lower NOx and CO. It is also shown thatthere are significant differences in the signal fromthe fast FID between the two cases. Figure 3shows the mass flow of HC calculated from theHC concentration trace and the calculated ex-haust mass flow. The second and third paper, [12,13], compares three fuels; iso-Pentane, iso-Octaneand a Japanese type gasoline, under stratifiedcharge conditions. The Japanese gasoline haslower final boiling point (170°C) than typicalEuropean gasolines. The most important HCsources for this engine is overmixing,undermixing and spray/wall interaction. Themeasurements indicate that overmixing is thedominating mechanism for HC emission forma-tion in this engine. There exists a fuel dependentoptimum injection timing that minimizes the sumof HC from overmixing, undermixing and spray/wall interaction. As the mixture preparation time,the time from SOI to ignition, is decreased,undermixing increases and with it the CO andsoot emissions grow.

Deposit formation in the combustion cham-ber and on the inlet valves represents anotherproblem when it comes to direct injection en-gines. The engine components most sensitive todeposit formation are the injector, spark plug, pis-ton and inlet valve neck. The injection pressureis too low to mechanically break the deposits andthe injector deposits can cause deterioration of

spray quality and reduction of flow capacity. Dis-ruption of the spray shape has a severe impacton the running quality of the engine.

The measurements in the deposit study havestarted and three of the five fuels have beentested. In figure 4 deposits on a piston from themulti-cylinder GDI engine subjected to the M-111cycle are shown. The study is expected to end inFebruary/March. So far the results have not beenevaluated, but it is evident that blow-by gases fromthe crankcase are important for inlet valve de-posits. The inlet manifold is designed in such away that only one of the two inlet valves per cyl-inder is supplied blow-by gases. The four inletvalves subjected to blow-by had a thick soft andoily deposit, see Figure 5, while the valves with-out blow-by were practically free from deposits.We believe that the engine oil content in the blow-by gases are the reason for the deposit build upon the inlet valves. The study will be completedduring the spring of 2000.

By cooperation with Cambustion Ltd. we hadthe oppportunity to use a fast NO measurementdevice, and completed a number of measure-ments. The data will be evaluated during thespring of 2000 and reported later.

Figure 4. Deposits on a piston in the GDI enginesubjected to the 60 h deposit accumulation cycle.

Figure 5. Deposits on one of the inletvalves subjected to blowby-gases duringthe 60 h deposit accumulation cycle.


Torque Sensors for Engine Applications

Mats Viberg, Professor

Stefan Schagerberg, PhD Student

Internal combustion engines are used in most oftodays automobiles. Due to environmental aspectsmore advanced engine control algorithms are re-quired in the future, for instance closed loop con-trol of the ignition angle. This emphasizes thedemand of sensors for retrieving information onthe combustion process. A common approachsuitable for production engines is to measure thecrankshaft speed fluctuations. The main advantageof this approach is that it is based on alreadypresent sensors. The drawback is however thatthe speed signal has to be numerically derivatedin order to relate to the cylinder pressure. At thecost of a new sensor, this can be circumventedby measuring the crankshaft torque directlywhich is the topic of this project. The work hasso far been focused on methods for recoveringthe cylinder pressure curve using both physicalmodeling and system identification techniques.Here, knowledge about the properties of the in-

stantaneous engine friction torque is desirable,which has motivated a measurement study.

Engine friction is mainly caused by the fric-tion between the piston and the cylinder wall, thusacting in the same way as the cylinder pressure.To isolate the cylinder pressure contribution inthe torque signal, a model for the instantaneousfriction is very beneficiary. A theoretical modelfor this based on lubrication theory was devel-oped in the 50’s. An alternative approach is ofcourse to perform direct measurements. Heremeasurements using sliding cylinder walls orstrain gauges mounted on the connecting rod havebeen considered. Since these methods requiresubstantial modifications to the engine a moreindirect friction estimation method termed thep-ω method was developed in the 80’s. Themethod uses measurements of cylinder pressure,crankshaft speed fluctuations and load torque toestimate the total engine friction.

Figure 6. Principle of the p-ω method.The estimated torque at “A” notdescribed by pressure or iner tia isfriction. The function g(ϕ) describesthe geometrical relationship betweenforce applied on the piston crown andindicated torque.

To evaluate the performance of such an approachexperiments are performed on a single-cylinderengine, which has been equipped with angle sen-sors at both ends of the crankshaft. The measure-ment system (AVL670 Indimaster) has been com-plemented with differential time measurementcapabilities to facilitate crankshaft speed meas-

urements. The results will be used to investigatethe statistical properties of the instantaneous fric-tion torque in order to improve the possibilitiesof cylinder pressure reconstruction from torquemeasurements.


Sven Andersson, Assoc. Professor

Jerzy Chomniak, Professor

Andreas Mattson, PhD Student

With further demands in the future to reduce thelegislated emission levels for the heavy duty die-sel engine, after-treatment devices like particulatetraps and selective catalytic reduction seem in-evitable. These devices will likely add a relativelyhigh cost to the engine. Even though after-treat-ment devices will be necessary it is of interest tokeep the raw emissions low to minimize the costand the complexity of the devices. The main regu-lated emissions from the diesel engine areparticulates and NOx. The characteristics of thediesel engine unfortunately tends to trade offthese emissions against one another, so that oneemission is decreased as the other one is in-creased. Finding a technical solution that reducesboth emissions or at least one while the secondremains unchanged, over most of the engine op-erating range without major fuel penalties, is ofgreat interest.

The air-fuel mixing process is important foremission formation. Elliptic nozzle holes have thepotential to increase air entrainment into thespray, which could lead to decreased emissionsfrom diesel combustion. Previous work has shownsome interesting results in a passenger car dieselengine and also in a single cylinder engine withoptical access. (The idea is based on results frominvestigations of gas jets, where the air entrain-ment for elliptical jets was increased substantiallycompared to circular jets.) The results showed areduction in NOx for a nozzle with ellipticalshaped orifices, in comparison with the referencenozzles with circular orifices. However, no effecton particulate, HC or CO emissions was observed.The passenger car diesel engine used in theseexperiments was a small-bore, high-speed dieseland it was believed that wall wetting was affect-ing the emissions. Therefore, the work was con-tinued during 1999 with a medium speed dieselengine so that wall wetting could be avoided.

These tests were made using nozzle orifices withnon-circular holes, close to elliptic, which had anaspect ratio of close to 2:1. Two different anglesof the elliptical major axis to the injectorcenterline were used. The elliptical holes havesharp inlets, while the circular holes have roundedinlets. The nozzles were tested at several differ-ent loads and speeds in the 2 liter 4 valve single-cylinder engine at Chalmers, equipped with anelectronically controlled unit injector using vari-able injection timing. Combustion parameters andemissions were compared for the different holes.

The result show that:

1. The elliptical nozzles are characterized withslightly longer ignition delays, lower maximumrates of energy release and longer combustiontimes.

2. The changes in injection and combustion proc-esses are small enough not to be reflected inincreased fuel consumption.

3. The smoke/BSNOx emission trade-off are

slightly affected by the nozzle shape.

4. A substantial improvement of fuel consumptio/BSNO

x emission trade-off is obtained for ellip-

tic nozzles at certain loads and speeds. The ef-fects are strong enough to consider optimiza-tion of the injector with noncircular nozzleholes and further testing.

The project has resulted in an SAE publication[14].

During 1999 a paper reporting the measure-ments of particulate emissions from diesel en-gines using different methods carried out at Uni-versity of Minnesota during 1998 was finished andsubmitted for publication [15].

Applied Combustion Diagnostics


There is today an increased interest in spray char-acterization mainly due to the many applicationsof sprays in aerosols and combustion systems, andthe need to understand the spray behavior in or-der to improve the performance of these differ-ing systems. In combustion engines, there is cur-rently also a trend towards increased use of fuelinjection based on spray injectors, being used indirect injected Otto and two stroke engines, andhigh-pressure injectors in Diesel engines [J. B.Heywood, “Internal combustion engine funda-mentals,” McGraw-Hill, Singapore (1988).]. Theoverall shape of a spray, and its penetration lengthinto the receiving media, can be measured bymeans of photography, or laser based techniquessuch as Mie scattering, or by Laser Induced Fluo-rescence (LIF) of the fuel vapor. However, meas-uring the internal properties of a spray, such asits breakup from bulk liquid into smaller drop-lets, their size and number density, is very diffi-cult. We have in the spray diagnostics project de-scribed here [16], done exploratory studies in:1. A low pressure cell with a Bosch injector2. An electrically motored direct-injected two-

stroke engine

Using laser sheet imaging of the Mie scatteredlight, we image cross sections through the spray,in order to reveal the internal structure throughthe optical density, which is measured with thismethod. It is a technically simple method, whichtakes advantage of the new, high-resolution CCDcameras available today and used in other projectsas well [17]. In a single image, it gives a 2-D crosssection through the spray, yielding both radial andaxial information. The time evolution of the sprayis covered by recording a sequence of imagesfrom different times in the spray cycle, as de-scribed in detail in the last Annual Report [63].

An overview of the experimental set-up is shownin Figure 7. The spray equipment consisted of anin-line diesel pump, with a peak pump pressureof approximately 350 bar, and a Bosch fuel injec-tor with a specially made, single hole nozzle, onaxis. The liquid injected is ethanol, chosen becauseit is transparent to 308 nm light. The ethanol spraywas injected into air at atmospheric pressure andat temperature 295K, which was the operatingcondition in this study. This operating condition,as well as the choice of ethanol as liquid, showsthat the research is for the moment in a modelexperiment stage.

In laser sheet imaging, a laser beam shaped intoa thin ribbon is sent through the spray. The planeof the laser defines the cross section of the spraythat is imaged, with the thickness of the laser rib-bon setting the depth of the image. The techniqueworks well in media that are optically thin, that iswhere the laser is only attenuated by 10% or lessafter passing through the spray. When the mediumis not optically thin, as in the core of a fuel spray,the quality of the images is degraded and inter-pretation becomes difficult. Laser sheet imagingcan be based on several different optical princi-ples, one of which is elastic light scattering fromliquid surfaces and droplets. With this method theliquid in the spray needs to be completely trans-parent for the laser light to avoid absorption andadditional attenuation of the light.

In order to get a quantitative and qualitativevalue of the spray properties the recorded im-ages has to be postprocessed. The images havebeen analyzed in collaboration with Prof. TomasGustavsson and Rafeef Abu-Gharbieh [18], thedepartment of Signals and Systems.

Laser Diagnostics of Dense Sprays

Arne Rosén, Professor

John Persson, Ass. professor

Michael Försth, PhD Student

Figure 7. Overview of experimental setup.


Figure. 8. Comparison of original andcompensated images. The profiles tothe right shows the dif ference betweenoriginal (thick line) and compensated(thin line) profiles at two dif ferentdistances from the nozzle.

Examples of images recorded with this setup areshown in Figure 8. The laser sheet is impinginginto the spray from the left side, giving rise to ahigher intensity on the left side of the sprays inthe images. The image intensity then falls rapidlytowards the right, and is very low at the rightedge of the sprays. This kind of attenuation hasbeen solved using the postprocessing as shownto the right in Fig. 8. Intensity profiles over thespray are shown to the right in the Figure. In theright of Fig. 8 are shown cross sections ofintensities for the original (thick line) andpostprocessed (thin line) pictures.

The laser measurements will now continue at theDepartment of Thermo and Fluid Dynamics in theprojects:

1. A new high pressure cell (100 bar) for spraycombustion studies.

2. Measurements on a running direct injected two-stroke engine.

Finally, in order to gain top-level competence andin order to establish an international scientificnetwork, Michael Försth has spent three monthsat Sandia National Laboratories in Livermore, Cali-fornia. There he participated in Raman measure-ments in a GM research engine [19].

InjectorInjector


Modeling of Spray Formation, Ignition and Combustionin Internal Combustion Engines

Valerie Golovitchev, Assoc. professor

Jerzy Chomiak, Professor

Niklas Nordin, PhD Student

Feng Tau, PhD Student

This report reviews recent results of the thirdstage of the CERC project with the aim of devel-oping a research CFD code for numericalsimulations of reacting multi-phase flows in pis-ton engines, including soot and NOx formation.

The KIVA3 and KIVA-3V versions of the KIVAcode are used for for simulation, with modifiedsub-models of fuel atomization, droplet evapora-tion, turbulence, ignition, combustion, NOx andsoot formation based on the RNG k-ε turbulencemodel. Such an approach allows for the treatmentof compressibility effects, detailed chemistry andturbulence/chemistry interaction accounting forthe reactant segregation, micro-mixing and sub-grid scale reaction rates.

The models of fluid dynamics, turbulence,chemical reactions, droplet evaporation, collision,dispersion and interaction with walls - a new op-tion of our KIVA-3V integrated model - were used

to reproduce the whole picture of turbulent spraycombustion.

Recently, the reduced, but still comprehensive(44 species, 195 reactions including NOx chemis-try) chemical mechanism for a generic aliphatichydrocarbon fuel has been especially developedfor the project, and applied to n-heptane (and iso-octane) combustion modeling. The model hasbeen supplemented by soot formation and oxida-tion processes accounting for ≈ 600 elementaryreactions between 117 species up to the fourtharomatic ring, A4, formation. The A4 then promptlyreacted to soot which is considered to be graph-ite or other forms of molecular carbon. The modelreduced for CFD application includes now 58species (up to acenaphthylene - curved PAH) and230 reactions, still of a reasonable complexity tobe applied to 2- and 3-D simulations.

Good agreement between computational andexperimental data for n-heptane ignition positionsand soot distributions at high pressures in a con-stant volume bomb has been achieved. The con-trol of the amount of soot formed in the constantvolume by means of the injection timing reduc-tion is well demonstrated. In engine simulations,the diesel oil was represented in a “hybrid” mode,with fuel physical properties corresponding to thereal diesel #2 grade, but with the combustionmechanism applicable to n-heptane chemistrywith a corrected f/o stoichiometry. Soot forma-tion in the Volvo AH10A245 DI Diesel enginefueled with such a fuel has been studied. the typi-cal simulation results are presented in Fig. 9. Here,soot distributions are shown for different CA. Thesoot reduction effect due to monitoring the in-jection timing appeared less pronounced in the2-D engine simulations due to the “shielding” ef-fect of the fuel injected in the axysimmetric spraypreventing oxidizer access to the cental regionof the flow normally taking place through thespacings between individual sprays. This is whythe further effect evaluation will be done using asector (60 deg) mesh.

The droplet/wall interaction included now inthe modeling is the subject of validation underconditions of a stationary piston.

Publications based on new results obtainedduring this stage of the project development arelisted in the references [20,21,22,23,24].

(a) ca=0.00 deg

(b) ca=+5.0 deg

(c) ca=+10.0 deg

(d) ca=+20.0 deg

Figure 9. Soot concentration (in g/m3) at differentcrank angles for the Volvo AH10A245 engine.


During 1999 two projects have been running onthe spray rigs, one about air entrainment meas-urements from diesel sprays and one about thedevelopment of a technique to measure the tran-sient discharge coefficient of a diesel nozzle.

In the air entrainment project an attempt wasmade to measure the air entrainment during atransient diesel spray. To do this a cylindrical tube,closed in one end and open in the other, was used.The tip of a diesel injector was inserted at theclosed end and the spray was injected along theaxis of the cylinder. The air entrained by the spraywas then measured through using a hot-wire an-emometer in a hole in the wall of the cylinder.Since this was the first project regarding this typeof measurements the outcome of the project wasmainly identifications of problems and recom-mendations how to overcome these. However, weare still pursuing the development of this tech-nique and we hope to obtain promising resultsin the near future [25].

The other project focused on the measure-ment of the discharge coefficient of a diesel noz-zle. Nozzle flow phenomena, like cavitation, canbe predicted numerically by CFD codes and havealso been investigated experimentally by some

Influence of Cavitation and Hydraulic Flip on Spray Formation,Ignition Delay, Combustion and Pollutant Formation

Sven Andersson, Assoc. Professor

Jerzy Chomiak, Professor

Lionel Christopher Ganippa, PhD Student

research groups, but the overall understandingof what is going on inside a diesel nozzle is farfrom understood. It is therefore important to beable to study the flow phenomena, direct throughvisual observations, or indirect, for instancethrough measurements of the discharge coeffi-cients.

In the present project a novel method of on-line evaluation of the instantaneous dischargecoefficient was developed using the spray im-pingement principle and the dynamic changes ofa diesel nozzle discharge coefficient over theentire injection time were studied including theinjector needle opening and closing periods.During the main injection period when the clos-ing needle is fully lifted the discharge coefficientvariations are modest and the average value ofthe discharge coefficient is about 0.75. The abovevalue when compared with low pressure injec-tion for which the discharge coefficient is about1 characterizes the effects of cavitation which arethus shown to be substantial. Hydraulic flip couldnot be achieved in the tests. The accuracy of themeasurements was checked using mass flowmeasurements for multiple injections and shownto be better than 2.5% [26].

This project is a cooperation between the dieselengine manufacturer Wärtsilä, engine controldeveloper Mecel and Chalmers University of Tech-nology through CERC. The projects aim is to in-vestigate the usage of in-cylinder ionization meas-urements for engine misfire and engine diagnoseson pre-chamber equipped SI combustion engines.The project reached full speed late May 1999.

A study on main and pre-chamber misfire de-tection for pre-chamber equipped gas combus-tion engines show high detection performancewhen using spark plug based ionization measure-ments. The influence of ionized gas from the mainchamber is under mid and high load conditionsubstantial and can be utilized to detect misfire.The current driven through the pre-chamberspark plug by a weak DC voltage is due to ionsinduced by the burning fuel in the pre-chamberduring early crank angles degrees and due to the

Mats Viberg, Professor

Dag Lundström, PhD Student

Control of fuel/air ratio in the pre-chamber of a lean-burn gas-engine by use of ionization measurements

main chamber combustion for crank angles afterTDC. A misfire detection approach based on aweighted logarithm of the ion-current samplesis very successful. With similar techniques is itshown possible to decide whether a mechanicalinjector problem or ignition circuitry problem ispresent due to their influence on the combus-tion and consequently on the ionization. The re-sults have been tested on measurements fromLindholmen Göteborg May 1998, and subse-quently at Zwolle, Netherlands October 1999.

The future aim of the project is to investigatethe potential of a more elaborate physical modeltogether with signal processing identificationtechniques in order to better separate the mal-functioning states that the engine can reach andadditionally to investigate the usage of the ioni-zation-signal for engine control.


Direct Injected Two-stroke Engine

The two-stroke engine uses just about 30% of anengine revolution for scavenging compared toone whole revolution for the four-stroke engine.The benefit is twice the number of power strokesfor the two-stroke engine at a given speed lead-ing to a superior power density. This makes thetwo-stroke an ideal engine in portable, hand-held,devices like chain saws, disc saws, various formsof cutters etc. Apart from having high power den-sity the engine is cheap, light, simple and robust.The drawback of the engine is that it is extremelydifficult, not to say impossible, to control the scav-enging process. In the two-stroke engine theburned gases from previous cycle are pushed outfrom the cylinder by the entering fresh air/fuel-mixture. Mixing of burned gases and fresh chargeand also fresh charge taking the shortest route tothe exhaust port (short-circuiting) are unavoid-able. Because of this there is a substantial loss offuel during the scavenging, about 20% of the de-livered fuel, leading to very high specific fuel con-sumption but also extremely high emissions ofunburned hydrocarbons (fuel).

The emissions requirements are becomingincreasingly stricter, even for hand-held devices,and can not be met in future with just an oxida-tion catalyst why, if the two-stroke should survive,the base emissions, especially HC, have to be re-duced drastically.

Because of the problems associated with scav-enging direct injection is especially attractive fortwo-stroke engines. With direct injection the scav-enging is performed with pure air and the fuel isinjected after the exhaust port have closed. In thisway no fuel is lost during scavenging and fuelconsumption and hydrocarbon emissions can be

Ingemar Denbratt, Professor

Jakob Fredriksson, PhD Student

reduced to levels comparable to the four-strokeengine. The difficulties are to create an close tostoichiometric mixture region at the spark plugover the full load and speed range of the enginein order to avoid partial burns and misfires butalso to utilise all available air at full load. The non-uniformities in mixture composition are largerthan in a normal carburetted two-stroke enginedue to the short time available for mixture prepa-ration. The mixture preparation depends on thespray characteristics (droplet size, spray-cone an-gle, injection velocity), flow field (velocity, turbu-lence, and length scale), wall interactions, fuelproperties (volatility) and temperature/pressurelevels apart from the pure geometry of the en-gine (injector location, cylinder-head and piston-crown shape). Another important parameter isinjection timing.

The target for this project is to study air/fueland internal EGR distribution in a two-stroke di-rect injected engine. Especially the area aroundthe spark plug at time of ignition is of vital inter-est. This will be done with the aid of LIF (in co-operation with Molecular Physics, Arne Rosén)and CFD calculations. As a measure of combus-tion quality HC emissions will be measured in theexhaust port with a fast FID. Also conventionalengine tests will be performed (emissions, fuelconsumption, heat release etc.)

In the first phase different injector positionsand piston designs will be evaluated.

The project was started during 1999 and a newPh.D. student has been employed. During 1999the test engine have been instrumented and in-stalled in a test cell, optical access have been ar-ranged (A Rosén) and a CFD mesh is underway.

The use alcohol as a fuel in compression ignitionengines is conceivable in different ways. In thisconcept, a part of the alcohol is catalytically con-verted to ether and water on-board. The productsof the conversion are separately introduced intothe engine air inlet (fumigation). With an optimizedengine it is shown that the performance as wellas emissions are comparable with those obtainedwhen running the engine on alcohol with PEG asignition improver. For EtOH fuel DEE is the etherfumigated into the engine and for MtOH fuel DMEis the ether fumigated.

DME has also been discussed as a neat fuelwith good ignition and emission properties forcompression ignition engines. The complete con-version of methanol to DME on-board is, however,not realistic. The experimental results of SAE pa-

per 950064 show that the compositions whichhave good ignition behaviour cannot be producedby a converter without carrying out separationsteps in the product stream (side product wateror unreacted methanol), independently of theachievable conversion rate. Ignition is only possi-ble if water and/or methanol is separated fromthe mixture. An additional separation step afterconversion is, however, connected with an addi-tional technical effort. Therefore, the concept withconversion of all methanol to DME, i.e. an enginerunning on neat DME, does not seem promising.

In Fig. 10, the concept “fumigation” isschematically presented. In this concept, a partof the methanol is catalytically converted andseparately introduced into the engine running onmethanol. If a conversion rate of approximately

Erik Olsson, Professor

Savo Gjirja, Researcher

On-board Manufactured Ethers as an ignition improverfor Alcohol Engines


80 % is achieved, the reaction mixture can be in-jected into the air intake without separating acomponent. Due to the small mass flows of metha-nol, the conversion can be performed in the gas-eous phase.

As reported in previous annular reports[61,62,63], CERC has investigated the possibili-ties of using ether as ignition improver in alco-hol fuelled diesel engines. A Volvo AH10A245turbo-charged diesel engine, which has previouslybeen optimised to run on ethanol (EtOH) withmixed in ignition improver of type PEG, [27], hasbeen used for the tests. The tests have not in-cluded on-board manufactured ethers, insteadpurchased ether has been used both premixedwith alcohol and injected into the engine air in-let during the fumigation tests. The maximumoutput of the engine was 180 kW at 2000 rpm,the maximum torque 1050 Nm at 1250 rpm.

When using premixing of alcohol and ether ithas proven to be necessary to mix in at least 60%ether. Performance as well as emissions are com-parable with those obtained when running theengine on alcohol with PEG as ignition improver[28]. The main emphasis has been put on the fu-migation technique, i.e. injecting ether into theair inlet of the engine. Instead of pure ether a

mixture of ether, alcohol and water has been usedin order to simulate the output from a dehydra-tion reactor. Testing has been completed usingEtOH [29] as well as MeOH [30] as the main fuel.

When using the fumigation technique theemissions of CO and HC increases due to theoverlapping valve period when both inlet andoutlet valves are open simultaneously. A new cam-shaft with shorter overlapping was thereforemounted (the same as used on natural gas firedengines) resulting in a significant reduction of CO,HC, and fuel consumption (bsfc). Still a slightlyhigher content of CO and HC is found in the ex-haust, as compared to tests with mixed in PEG.The weighted emissions according the 13 stepECE R49 test cycle are shown in figure 11 forMeOH as well as EtOH fuels. When using an oxi-dising catalyst both CO and HC will easily be re-duced to levels of 0.1-0.2 g/kWh.

A micro gas chromatography (GS) withquadrupole detector and mass spectrometry (MS)was uses to complement the conventional regu-lated emission equipment. These measurementsshow expected levels of MeOH and DME in theexhaust but remarkably no traces of hydrocarbonsand acetaldehyde’s were found.

MeOH-tank

pump

onboardreactor fumigation

DME % (Rpm =2000)

DME % (Rpm=1250)

DME kg/h(Rpm 2000)

DME kg/h(Rpm 1250)

Figure 10. Scheme of “fumigation”.

Figure 12. DME flow versusengine load in %.

Figure 11. Emissions according to the ECE.

g/kW

h

DM

E in

kg/

harc

in %

0

5

10

15

20

10 4030200 80706050

Load in %


problems for DME-fumigation have not beensolved yet. Especially transient operation and coldstart compatibility are a challenge. The heating-up behaviour of a reactor has been estimatedusing a simplified model which shows that thecold start problem should be manageable.Figure 13 shows the influence of space velocityon the conversion curves for Nafion and γ-Al2O3.Increasing the space velocity shifts the curves tohigher temperatures. Above 220°C for Nafion or350°C for γ-Al2O3 the reaction is controlled byequilibrium for all space velocities studied. Table1 shows how space velocity can be correlatedwith the mass of catalyst required for providingenough DME for a fumigated diesel engine of 180kW output. The calculation is based on the as-sumption that 4 kg/h of DME are required by theengine and that 80% conversion needs to bereached.

The mass of catalyst required is about the samefor both types. It is clear that, from the point ofview of extra weight for the vehicle, space veloc-ity is not decisive. Low catalyst masses mean, how-ever, low thermal load which is important in thestart-up of the converter.

0.0

0.2

0.4

0.6

0.8

1.0

100 150 200 250 300 350 400

temperature [°C]

conversion of MeOH

equilibrium

Nafion 3.0 1/h

Nafion 8.9 1/h

Nafion 13.9 1/h

Al2O3 3.9 1/h Al2O3 8.0 1/h Al2O3 12.3 1/h

In order to optimise the DME flow through thefumigation system, further tests with variationof the DME injector flow were conducted andthe minimum flow for best engine performancewas obtained. Figure 12 shows the DME flow inkg/h as well as in % of the total injected fuel(DME+MeOH) versus engine load in %.

In conclusion it is found that use of ether asignition improver in alcohol engines gives com-parable performance and emissions as when us-ing alcohol’s with mixed in PEG, which is stand-ard practice in a large number of heavy vehiclesin Sweden today.

The MeOH conversion has been tested withdifferent catalysts under various conditions atPaul Scherrer Institute (PSI) in Switzerland [31].The experiments with the catalysts Nafion andacidic γ-Al2O3 show encouraging results. Becauseof its superior thermal stability and the low costs,acidic γ-Al2O3 has been selected as the mostpromising catalyst for converting methanol toDME in sufficient rates for an on-board applica-tion. Providing DME for fumigation in a 180 kWengine will require less than 1 kg of catalyst. Thecompact catalyst is necessary for efficient andfast start-up of the process. The reactor design

Figure 13. Conversion of methanol to DMEin micro-reactor (1700 mg of catalyst) as afunction of temperature on γ-Al2O3 andNafion catalysts, for space velocitiesbetween 3 and 13.9 h-1, as indicated inlegend. System pressure: 1.5 - 2.5 bar abs.


Both catalysts show potential for the applica-tion in the on-board generation of DME for fumi-gation. Nafion has higher activity and hence theadvantage of lower operation temperature.Nafion, as an organic polymer, has the disadvan-tage of thermal degradation at temperatures ex-ceeding the design temperature of operationwhich should not be above 220°C. γ-Al2O3 hasthe advantage of being resistant to overheating.Operation at 350°C requires higher heat input atstart-up. This should, however, not be a problem,as the heat-up rate of an alumina catalyst is ex-

pected to be in the same order as for Nafion. Op-eration at high temperature bears the danger ofcoking which would mean that a regenerationstep (coke burning) would be necessary fromtime to time. The actual loss of activity due tocoking (γ-Al2O3) or thermal degradation (Nafion)will have to be assessed with long-term experi-ments. Although it has shown the lowest activity,γ-Al2O3 is favoured as the preferred candidate forusing in the converter, mainly due to its muchlower cost.

Table 1: Calculated catalyst massrequired for producing 4 kg DME perhour in a catalytic conver ter.

Nafion γ-Al2O3WhSV[1/h]

catalystmass [g]

WhSV[1/h]

catalystmass [g]

3.0

8.9

13.9

2300

780

500

3.9

8.0

12.3

1800

875

565


HumanresourcesStaff Associated with the Activities of CERCDuring the period, Chalmers University of Technology has engaged ten Ph.D.students, of whom six are at the Department of Thermo and Fluid Dynamics,one at the Department of Physics (Molecular Physics Group), one at theDepartment of Physical Chemistry and two at the Department of Signals andSystems (Signal Processing Group).

The senior research personnel associated with the activities correspond toapproximately five full-time positions. The total work put on by theparticipating companies will correspond to approximately one full-timeposition. The operational group consisting of personnel working at CERCduring 1998 is as follows:

Jerzy Chomiak Professor Emeritus (Internal Combustion Engines)Erik Olsson Professor Emeritus (Thermo and Fluid Dynamics)Valeri Golovitchev Associate Professor (Internal Combustion Engines)Andrei Lipatnikov Researcher (Internal Combustion Engines)Ingemar Denbratt Professor (Internal Combustion Engines)Sven Andersson Associate Professor (Internal Combustion Engines)Rolf Berg Researcher (Internal Combustion Engines)Savo Gjirja Researcher (Internal Combustion Engines)Arne Rosén Professor (Molecular Physics)John Persson Assistant Professor (Molecular Physics)Mats Viberg Professor (Signal Processing)Jim Olsson Associate Professor (Physical Chemistry)Jörgen Pedersen Senior Researcher (Physical Chemistry)Anders Karlström Director (CERC)Håkan Sandquist Ph.D. Student (Internal Combustion Engines)Johan Wallesten Ph.D. Student (Internal Combustion Engines)Niklas Nordin Ph.D. Student (Internal Combustion Engines)Tao Feng Ph.D. Student (Internal Combustion Engines)Andreas Matsson Industrial Ph.D. Student (Internal Combustion Engines)Lionel C. Ganippa Ph.D. Student (Internal Combustion Engines)Jakob Fredriksson Ph.D. Student (Internal Combustion Engines)Michael Försth Ph.D. Student (Molecular Physics)Dag Lundström Ph.D. Student (Signal Processing)Stefan Schagerberg Ph.D. Student (Signal Processing)

A number of representatives from the participating industries are also involvedin the activities connected to CERC, without working directly in specific CERCprojects. Instead, the group of experts within each project consists ofpersonnel from the companies who coordinate the activities, together withthe project leader. All persons working in the projects have signed specialagreements of secrecy.

Management of CERC

Within Chalmers University ofTechnology, CERC is an independentunit with its own budget andaccounting. The activities of CERCare governed by the Board, and theBoard of Directors is appointed bythe President of Chalmers UniversityofTechnology in consultation withthe par ticipating companies.

CERC’s Director – Anders Karlström– is the operational head and isresponsible for coordination withinthe center. The Board consists ofthree members from the academiccommunity and six representativesof the par ticipating companies:

Jan Crister Persson(Chairman of the Board), TheSwedish Institute of ProductionEngineering Research

Ingemar DenbrattChalmers University of Technology

Jerzy ChomiakChalmers University of Technology

Bo AndreassonHusqvarna AB

Arne RosénChalmers University of Technology

Tommy BjörkqvistSAAB Automobile AB

Göran HammarbergScania CV AB

Sivert HiljemarkVolvo Car Corporation

Sören UddVolvo Truck Corporation

The Research of CERC is pursued inaccordance with the projectsdescribed above and the projectleaders repor t the results achieved


Table 3. Actual contributions from participants 1999 (KSEK).

Revenues Total Cash ”In kind”

ABB Industrial Systems AB 880 430 450 1

Aspen Petroleum AB 140 100 40

Husqvarna AB 412 250 162

MECEL AB 300 100 200

SAAB Automobile AB 250 250 0

Scania CV AB 370 350 20

Den norske stats oljeselskap s.e. 150 100 50

Volvo Truck Corporation 2 030 960 1 070 2

AB Volvo Penta 100 100 0

Volvo Car Corporation 1 400 1 000 400 3

Wär tsilä NSD Sweden AB 155 50 105

Energimyndigheten 6 000 6 000 0

Chalmers Univ of Technology 8 261 750 7 511 4

TOTAL 20 448 10 440 10 008

BUDGET 23 020 10 820 12 200

Comments on “in kind” contributions:1 Development of a new torque sensor.2 Industrial PhD student and equipment.3 Equipment for DI-project and consultations.4 See Table 4 for details.

Table 4. Expenses at Chalmers 1999 (KSEK).

Paid by CTHPersonnel expenses Total CERC “in kind”

Project director 1 044 1 044 0

Ph.D Student 5 340 4 140 1 200

Professor 1 450 250 1 200

Research engineer 2 656 1 495 1 161

Technician 254 254 0

External consultants 311 311 0

Equipment and Development

Computers 52 52 0

Programs 0 0 0

Materials 328 328 0

Montage 0 0 0

Testing (rig etc.) 4 769 1 519 3 250

Instruments 100 100 0

Miscellaneous equipment 205 205 0

Miscellaneous

Travel 517 517 0

Overhead 516 516 0

Premises 768 68 700

Unspecified 0 0 0

Salaries 11 055 7 494 3 561

Equipment & Development 5 454 2 204 3 250

Miscellaneous 1 801 1 101 700

TOTAL 18 310 10 799 7 511

BUDGET 15 780

Finances during theperiod 1998-2000During 1998-2000, the budget following the agreement between thethree parties, given in Table 2 was established.

In the summary of the budget above some of the revenues fromthe participating companies are “efforts in kind”. Table 3 shows ac-tual input of cash respectively “efforts in kind” for the participatingcompanies during 1999.

In Table 4, the cost of activities at Chalmers during 1999 are given,distributed by cost categories.

In Table 5 a summary of the project expenses has been included.

Table 2. Total budget for 1998-2000 period (KSEK).

Revenues 1998 1999 2000

Nutek 6 000 6 000 6 000

Husqvarna AB 550 550 550

SAAB Automobile AB 1 000 1 000 1 000

Scania CV AB 400 400 400

Volvo Truck Corp. 2 010 2 010 2 010

Volvo Car Corp. 1 250 1 250 1 250

MECEL AB 500 500 500

Wär tsilä Diesel AB 400 400 400

Statoil A.S. 150 150 150

Aspen Petroleum AB 150 150 150

ABB Industrial Systems AB 760 760 760

Volvo Penta AB 150 150 150

Chalmers Universityof Technology 9 250 9 250 9 250

TOTAL 17 020 17 020 17 020


Table 5. Summary of project expenses (KSEK).

CTH CTH CTH CTH Industr y OverallProject: Salaries Equipm. Misc. Total Total Total Budget

Studies of flame propagation,quenching and hydrocarbon after-burningin lean highly turbulent mixtures 1 879 12 78 1 969 150 2 119 1 620

The effect of fuel preparation on the operationalcharacteristics of a direct injection engineand deposit formation 1 260 566 62 1 888 370 2 258 2 230

Time resolved chemically detailed sampling 250 70 50 370 0 370 250

Control of engines by a torque-sensor 547 30 204 781 470 1 251 1 270

Applied combustion diagnostics 349 1 435 7 1 791 900 2 691 2 600

Laser diagnostics 1 080 130 300 1 510 120 1 630 1 660

Modeling of spray formation, ignition, andcombustion in internal combustion engines 2 590 25 111 2 726 135 2 861 2 210

Influence of cavitation and hydraulic flip onspray formation, ignition delay, combustionand pollutant formation 1 306 1 100 34 2 440 0 2 440 1 690

Direct injection 2-stroke engine 631 69 0 700 102 802 1 000

Control of fuel/air ratio in the pre-chamberof a lean-burn gas-engine by use ofionization measurements 183 0 115 298 250 548 500

On-board manufactured ethers asignition improvers for alcohol engines 0 0 0 0 0 0 0

Visiting researcher 250 0 0 250 0 250 250

Administration* 731 2 019 840 3 590 0 3 590 3 300

TOTAL 11 056 5 456 1 801 18 313 2 497 20 810 18 580

* “In kind” CTH equipment covering laboratory rebuilding


References1. Lipatnikov, A.N. and Chomiak, J. “A Self-

Similar Regime of Premixed TurbulentFlame Development,” submitted to the28th Symposium (International) onCombustion.

2. Lipatnikov, A.N. and Chomiak, J.“Dependence of Heat Release on ProgressVariable in Premixed TurbulentCombustion,” submitted to the 28thSymposium (International) on Combustion.

3. Lipatnikov, A.N. and Chomiak, J. “Modelingof Pressure and Non-Stationar y Effects inSpark Ignition Engine Combustion: AComparison of Dif ferent Approaches,”submitted to 2000 International SAESpring Fuels & Lubricants Meeting &Exposition.

4. Lipatnikov, A.N. and Chomiak, J. “Transientand Geometrical Ef fects in ExpandingTurbulent Flames”, Combustion Scienceand Technology, in press.

5. Lipatnikov, A.N. and Chomiak, J. “ANumerical Study of the Turbulent FlameSpeed Development After Ignition,” JointMeeting of the British, German and FrenchSections of the Combustion Institute.Abstracts. 18-21 May 1999, Nancy,France, pp. 65-67, 1999.

6. Lipatnikov, A.N. and Chomiak, J. “BurningVelocity at Strong Turbulence: Role ofFlame Geometr y and Transient Ef fects”,Proceedings of the MediterraneanCombustion Symposium - 99, Eds. by F.Beretta. pp. 1038-1049, 1999.

7. Lipatnikov, A.N. and Chomiak, J. “ANumerical Study of Turbulent Flame SpeedDevelopment in the Spherical Case,” 17thInternational Colloquium on the Dynamicsof Explosion and Reactive Systems, July25-30, 1999, Heidelberg, Germany. CDISBN 3-932217-01-2. Paper 026.

8. Chomiak, J. and Lipatnikov, A.N. “OnMechanisms Contributing to the Bending ofTurbulent Burning Velocity Curve,” JointMeeting of the British, German and FrenchSections of the Combustion Institute.Abstracts. 18-21 May 1999, Nancy,France, pp. 9-11, 1999.

9. Lipatnikov, A.N. and Chomiak, J. “Effectsof Turbulence Length Scale on FlameSpeed: a Modelling Study,” EngineeringTurbulence Modelling and Measurements4, Eds. by W. Rodi and D. Laurence,Elsevier, Amsterdam, pp.841-850, 1999.

10. Wallesten, J. “Modeling of FlamePropagation in Spark Ignited Engines”.Licentiate thesis. 1999.

11 Sandquist, H. and Denbratt, I.“Comparison of Homogeneous andStratified Charge Operation in a DirectInjection Spark Ignition Engine”, presentedat The 15th Internal Combustion EngineSymposium, Seoul, Korea, 13-16 July,1999.

12 Sandquist, H. and Denbratt, I. “Influenceof Fuel Volatility on Cycle-ResolvedHydrocarbon Emissions from a DirectInjection Spark Ignition Engine”, presentedat the Gasoline Direct Injection EngineCongress, Munich, Germany, 16-17November, 1999.

13 Sandquist, H. and Denbratt, I. “Sources ofHydrocarbon Emissions from a DirectInjection Stratified Charge Spark IgnitionEngine”, to be presented at CEC/SAESpring fuels & lubricants meeting, Paris,France, 19-22 June, 2000.

14 Andreas Matsson, Lisa Jacobsson, SvenAndersson, ”The Effect of Elliptical NozzleHoles on Combustion and EmissionFormation in a Heavy Duty Diesel Engine ”,SAE 2000, Detroit, Paper 2000-01-1251

15 Moh’d Abu-Qudais, AndreasMatsson,.David Kittelson, ”Combination ofMethods for Characterization DieselEngine Exhaust Par ticulate Emissions”,submitted for publication

16 R. Abu-Gharbieh, J. L. Persson, M. Försth,A. Rosén, A. Karlström, T. Gustavsson, “ACompensation Method for AttenuatedPlanar Laser Images of Optically DenseSprays, ” Applied Optics (2000), in press.

17 M. Försth, “Laser Diagnostics andModeling of the Coupling betweenHeterogeneous Catalytic and Gas-PhaseOxidation of Hydrogen”, Licentiate thesis(1998).

18 R. Abu-Gharbieh, “Laser Sheet Imagingand Image Analysis Applied to SprayDiagnostics”, Licentiate thesis (1999).

19 M. Försth, P. C. Hinze, P. Miles, ”Onedimensional temperature measurements inan IC engine using spontaneous Ramanscattering”, Ar ticle in preparation.

20 Golovitchev, V.I., Nordin, N., Chomiak, J.,and Nishida, K., Evaluation of ignitionquality of neat DME at Diesel-likeconditions. Paper published in theProceedings of the InternationalConference ICE99: Internal CombustionEngines: Experiments and Modeling, Capri-Naples, September 12-16 (1999)

21 Tao, F., Golovitchev, V.I., and Chomiak, J.,Numerical Modeling of Auto-Ignition,Combustion, and Soot Formation in n-Heptane Sprays in a High PressureConstant-Volume Chamber. Paperpublished in the Proceedings of theInternational Conference ICE99: InternalCombustion Engines: Experiments andModeling, Capri- Naples, September 12-16(1999)

22 Golovitchev, V.I., Tao, F., and Chomiak, J.,Numerical Evaluation of Soot FormationControl at Diesel-Like Conditions byReducing Fuel Injection Timing, SAE Paper99FL-388 (1999)

23 Golovitchev, V.I., Nordin, N., DetailedChemistr y Sub-Grid Scale Model ofTurbulent Spray Combustion for the KIVAcode, Paper published in the Proceedingsof the ASME 1999 Fall TechnicalConference. Session ”In-cylinder FlowCombustion Measurements and Model-ing”, October 16-20, Ann Arbor, Michigan,USA (1999)

24 Golovitchev, V.I., Nordin, N., KIVA 3-DSimulations Using a New DetailedChemistr y Diesel Spray CombustionModel, Paper published in the Proceedingsof the Workshop ”Combustion Modeling inI.C.E.”, December 14-15, Cassino, Italy(1999)

25 B. van Norel, R. I. le Grand, ”How tomeasure the air entrainment in dieselsprays”, Internal repor t 99/10,Depar tment of Thermo and FluidDynamics, Chalmers University ofTechnology, 1999.

26 Lionel C. Ganippa, J. Chomiak, S.Andersson, Transient Measurements ofDischarge Coef ficients of Diesel Nozzles”,submitted for publication

27 S. Gjirja, “Engine Design Optimization, aPractical Technology for OptimumPer formance and Emissions of an EthanolFueled Engine”, Paper No 97EL008,International Conference Proceedings,30th ISATA, Florence, Italy, 1997.

28 S. Gjirja, E. Olsson, “Ether as IgnitionImprover and Its Application on EthanolFueled Engine”, Internskrift Nr 97/15,Thermo & Fluid Dynamics, ChalmersUniversity of Technology, 1997. Alsopublished as KFB-Meddelande 1997:38.

29 S. Gjirja, E. Olsson, A. Karlström, “EtherFumigation, a New Alternative for the NeatEthanol Diesel Engine”, Paper No98EL008, International ConferenceProceedings, 31st ISATA, Clean PowerSources & Fuels. Special InnovativeConference: Intelligent Transpor tationSystems, Düsseldor f, Germany, 1998.

30 S. Gjirja, E. Olsson, A. Karlström,“Investigations on Methanol Engine withDME Fumigation”, Paper 99CPE007, 32nd

ISATA, June 14-17, Vienna, Austria, 1999.

31 H. Armbruster, J. Van Gunsteren, S. Stucki,E. Olsson, S. Gjirja, “On-board conversionof alcohols to ethers for fumigation indiesel engines”, Paper at InternationalSymposium on Alcohol Fuels, ISAF XIII, inStockholm 3-6 July 2000.


Other references not mentioned in the text

32. Lipatnikov, A.N., J. Wallesten, J. Chomiak,and J. Nisbet, “Computations ofCombustion in Bombs and an SI-EngineUsing a Turbulent Flame Speed ClosureModel and Modified FIRE Code”.Computational Technologies for Fluid/Thermal/Chemical Systems with IndustrialApplications, Vol. II, ASME, New York, pp.199-206, 1998.

33. Lipatnikov, A.N., Wallesten, J., and NisbetJ., “Testing of a Model for Multi-Dimensional Computations of TurbulentCombustion in Spark Ignition Engines”,COMODIA 98 - The Four th InternationalSymposium on Diagnostics and Modelingof Combustion in Internal CombustionEngines}, JSME, Kyoto, pp. 239-244,1998.

34. Wallesten, J., Lipatnikov, A.N., and NisbetJ., “Turbulent Flame Speed Closure Model:Fur ther Development and Implementationfor 3-D Simulation of Combustion in SIEngine”, SAE Paper 982613, 1998

35. Wallesten, J., Lipatnikov, A.N., Chomiak,J., and Nisbet J., “3D Simulation ofCombustion in SI Engine Using a TurbulentFlame Speed Closure Model”. Expose överförbränningsforskningen i Sverige,Chalmers Institute of Technology,Gothenburg, 21-22 October 1998, p.62.

36. Lipatnikov, A.N. and Chomiak, J., “Effectsof Turbulence Length Scale on FlameSpeed: A Modelling Study”, submitted to4th International Symposium onEngineering Turbulence Modelling AndMeasurements, Corsica, France, May 24-26, 1999.

37. Lipatnikov, A.N. and Chomiak, J.,“Randomness of Flame KernelDevelopment in Turbulent Gas Mixture”,SAE Paper, 1998.

38. Lipatnikov, A.N. and Chomiak, J.,“Lewis Number Effects in PremixedTurbulent Combustion and HighlyPer turbed Laminar Flames”, CombustionScience and Technology, 1998, in press.

39. Lipatnikov, A.N. and Chomiak, J., “BurningVelocity at Strong Turbulence: Role ofFlame Geometr y and Transient Ef fects”,submitted to Mediterranean CombustionSymposium, Antalya, Turkey, June 20-25,1999.

40. Håkan Sandqvist, Ingemar Denbratt, ÅsaIngemarsson, Jim Olsson, “Influence ofFuel Volatility on Emissions andcombustion in a direct injection SparkIgnition Engine”. SAE-paper 982701. SAEFall meeting San Fransisco. 1998

41. Åsa Ingemarsson, “Emissions fromcombustion and pyrolysis from liquid andsolid fuels investigated using GC/MS andGC/FTIR/FID”. Licentiate thesis 1998.Institutionen för fysikalisk kemi, Chalmerstekniska Högskola.

42. Åsa Ingemarsson, Jörgen Pedersen, JimOlsson, “Sampling from n-Heptane/airflames with on-line GC/FID and GC/MS.Two dif ferent sampling strategies”.Internal repor t 1997-03-24

43. Åsa Ingemarsson, Jörgen Pedersen, JimOlsson, “Emissions analysis GC/MS on anEthanol/Ether Fuelled engine”. Internalrepor t 1997-06-23.

44. Åsa Ingemarsson, Jörgen Pedersen, JimOlsson, “Summary of GC/MSmeasurements on a Methanol/DMEengine”. Internal Repor t 1998-06-17.

45. Åsa Ingemarsson, Jörgen Pedersen, JimOlsson, “Identification of key compoundsin gasoline and oxygenate flamecombustion”. Internal repor t 1997-04-08.

46. Åsa Ingemarsson, Jörgen Pederssen, JimOlsson, “Emisionsanalys avoxygenatbränslen. Speciellt etanol/dietyleter blandningar. Metod för snabbanalys med mikro GC”. Internal repor t1996-10-25.

47. Åsa Ingemarsson, Jörgen Pederssen, JimOlsson, “Emissionsanalys avoxygenatbränslen. Speciellt etanol/diethyleter blandningar. Metod för GC/MSanlys med GCD”. Internal repor t 1997-03-24.

48. Jörgen Pedersen, Åsa Ingemarsson, JimOlsson, “Oxidation of Rapeseed Oil,Rapeseed Methyl Ester (RME) and DieselStudied With GC/MS”. Chemosphere1998.

49. Pär Bergstrand och Mattias Marklund,“Design and construction of a spray rig forinvestigation of cavitation in dieselinjectors”, MSc thesis, Depar tment ofThermo and Fluid Dynamics, ChalmersUniversity of Technology, 1998.

50. Matsson, A., “Dif ferent Methods ForCharacterization of Diesel Engine ExhaustParticulate Emissions”, Presented at theCERC seminar, Chalmers, Göteborg, 1999-03-03.

51. Golovitchev, V.I., Nordin, N., and Chomiak,J., “Neat Dimethyl Ether:Is it Really Diesel Fuel of Promise ?”.SAE Paper 982537 (1998)

52. Golovitchev, V., and Chomiak, J.,“Evaluation of Ignition Improvers forMethane Autoignition”. Journ. Combust.Sci. and Tech., vol. 135, pp. 31-47 (1998)

53. Nordin, N., Golovitchev, V.I., and Chomiak,J., “Computer Evaluation of DI DieselEngine Fueled with Neat Dimethyl Ether”.Proceedings of the 22nd CIMAC, 18-21May, Copenhagen, vol.2, pp. 408-421(1998)

54. Nordin, N., “Numerical Simulations of Non-Steady Spray Combustion Using theDetailed Chemistr y Approach”. Thesis forthe degree of Licentiate of Engineering,Chalmers University of Technology (1998)

55. Gjirja, S., Olsson, E., Karlström, A.,Ingemarsson, Å., Berg, R.,”Alcohol Engines with Ether as IgnitionImprovers. Literature Review andSuggestions”. Internskrift Nr 96/27,Thermo & Fluid Dynamics, ChalmersUniversity of Technology, 1996.

56. Gjirja, S., Olsson, E.,”Ether as IgnitionImprover and Its Application on EthanolFueled Engine”, Internskrift Nr 97/15,Thermo & Fluid Dynamics, ChalmersUniversity of Technology, 1997. Alsopublished as KFB-Meddelande 1997:38.

57. Golovitchev, V., Nordin, N., Chomiak, J.,”Modeling of Spray Formation, Ignition andCombustion in Internal CombustionEngines”. Publication Nr 98/1, Thermo &Fluid Dynamics, Chalmers University ofTechnology, 1998.

58. Gjirja, S., Olsson, E., ”On-BoardManufactured Ethers as an IgnitionImprover for Alcohol Engines. ReferenceTest with Poly-Ethylene-Glycol (PEG)Ignition Improver”. Internskrift Nr 98/9,Thermo & Fluid Dynamics, ChalmersUniversity of Technology, 1998.

59. Gjirja, S., Olsson, E., ”OnboardManufactured Ethers as an IgnitionImprover for Alcohol Engines. Effects ofthe DME Fumigation on Methanol EnginePer formance and Emission Levels”.Internskrift Nr 98/10, Thermo & FluidDynamics, Chalmers University ofTechnology, 1998.Systems, Düsseldor f,Germany, 1998.

60. Gjirja, S., Olsson, E., Karlström, A.,”Considerations on Engine Design andFuelling Technique Effects on QualitativeCombustion in Alcohol Diesel Engines”.SAE International Fall Fuels and LubricantsMeeting, Paper 98FL-322, San Fransisco,USA, October 19-22, 1998.

61. CERC – Combustion Engine ResearchCenter ”Annual Repor t 1996”.Chalmers University of Technology, http://www.tfd.chalmers.se/CERC/ (1996).



64. Lipatnikov, A.N. and Chomiak, J.,“A Simple Model of Unsteady TurbulentFlame Propagation”, SAE Paper 972993(1997).


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65. Lipatnikov, A.N. and Chomiak, J.,”Modeling of Turbulent Flame Developmentin Spark Ignition Engines”, Proceedings of3rd International Conference on InternalCombustion Engines: Experiments andModeling, Instituto Motori, Naples, pp.75-82 (1997).

66. Lipatnikov, A.N. and Chomiak, J.,”Simulations of the Ef fect of StrongPer turbations on Laminar Flames”, 16thInternational Colloquium on the Dynamicsof Explosions and Reactive Systems.August 3-8, 1997. ConferenceProceedings, University of Mining andMetallurgy, Cracow, pp. 406-409 (1997).

67. Lipatnikov, A.N. and Chomiak, J.,”Modeling of Turbulent FlamePropagation”, Chalmers University ofTechnology, Göteborg (1997).

68. Lipatnikov, A.N. and Chomiak, J.”Lewis Number Effects in PremixedTurbulent Combustion and HighlyPer turbed Laminar Flames”, submitted toCombust. Sci. and Tech. (1997).

69. Lipatnikov, A.N. and Chomiak, J.,”Minimum Ignition Energy andRandomness of Flame Development inTurbulent Gas”, XVth InternationalSymposium on Combustion Processes,Zakopane, September, 8-12, 1997.Abstracts Polish Academy of Sciences, p.20 (1997).

70. Burgdor f, K. and Karlström, A.,”Using Multi-Rate Filter Banks to DetectInternal Combustion Engine Knock”.SAE Paper 971670 (1997).

71. Karlström, A., Lundström, D. and Viberg,M., ”Knock Localization in InternalCombustion Engines Using MultiplePressure Sensors”. Chalmers University ofTechnology, Techn. Repor t-CTH-TE-66(1997).

72. Lundström, D., Karlström, A.,“Transient Identification using a FractionalDerivative Model”. Accepted for publicationat the European Control ConferenceECC 99, August 31 – September 3,Karlsruhe (1999).

73. Andersson, S., Wallesten, J.,”Ethanol and Ether (DEE) SprayExperiments – PDA Measurements andVideo Imaging”, Repor t No 97/23, Dept. ofThermo and Fluid Dynamics, ChalmersUniversity of Technology (1997).

74. Persson, J., Försth, M., Rosén, A., ”Spraydiagnostics 970401”, Repor t No 98/1,Dept. of Physics (the Molecular PhysicsGroup), Chalmers University of Technology(1997).

75. Golovitchev, V. and Nordin, N.,”FIRE code, v6.2b: Droplet EvaporationModels”. Chalmers University ofTechnology, Dept. of Thermo and FluidDynamics, Technical Repor t 97/22 (1997).

76. Nordin, N. and Golovitchev, V., ”NumericalEvaluation of n-Heptane Spray Combustionat Diesel-Like Conditions”. The 7thInternat. KIVA Users Meeting at the SAECongress, Februar y 23, 1997, Detroit,Book of Abstracts, pp.1-5 (1997).

77. Golovitchev, V. and Nordin, N., ”NumericalEvaluation of Dual Oxygenated Fuel Setupfor DI Diesel Application”. SAE Paper971596 (1997).

78. Golovitchev, V., Nordin, N. and Chomiak,J., ”Modeling of Spray Formation, Ignitionand Combustion in Internal CombustionEngines”. Annual Repor t (1997).


Info

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ion

Off

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Cha

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s 2000

The Competence Center in Internal Combustion Engines(Combustion Engine Research Center – CERC) was establishedat Chalmers University of Technology in cooperation with Swedishengine manufacturers and the Swedish Board of Technical andIndustrial Development (NUTEK) in 1995. For the period 1997-2001 the coordination is transferred to the Swedish NationalEnergy Administration. The aim of the center is to strengthenthe activities concerning the relevant basic industrial researchassociated with Internal Combustion Engines.

CERC concentrates on research aiming for reductions both of fuelconsumption and engine emissions. The projects at the centerinclude both experimental validation of models and systems andnew concepts associated with alternative fuels. Furthermore,new diagnostic tools are used in engine research. Severalprojects concentrate on different types of spray formation,spray diagnostics and flame propagation. Strong competencein thermodynamics, mass and heat transport, kinetics andmeasurement techniques will be built up.

CERC

CERCChalmers University of TechnologySE-412 96 GöteborgSweden

Telephone +46 (0)31-772 1401Fax +46 (0)31-18 09 76E-mail [email protected] www.tfd.chalmers.se/CERC/

cerc - annual report 1999 - chalmers · 3 cerc – annual report 1999 preface over the past five...

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