Professor Egon Lang is working with industry collaborators on innovations in the field of fluid dynamics that are having a great impact on products and services people use every day

What does your work entail? Why are flow and transport processes so important in engineering?

We concentrate on unsteady fluid dynamics; problems such as the simulation of fluid flow around a human head to detect possible noise sources influencing the performance of hearing aids. In many energy conversion and material production processes, flow and transport phenomena play an important role in determining their efficiency: I support my colleagues in optimising energy efficiency.

How did your work at Sulzer, an industrial engineering and manufacturing firm, prepare you for your current research?

At that time, Sulzer had a large R&D department. We carried out basic and applied research for most of the departments in the area of fluid dynamics, ranging from developing a left ventricle-assist device to optimising main nozzles for air jet weaving machines. The most challenging and exciting tasks involved adapting techniques and methods recently developed in university laboratories to industrial problems; for instance, the application of numerical

methods for simulating fluid flow in industrial processes.

How important is partnership with industry to your activities today?

In my current research, collaboration with industry is essential. It is the mission of the Universities of Applied Science in Switzerland to support the R&D activities of SMEs to help them compete in a global market. The government-run Commission for Technology and Innovation supports such collaboration.

Could you explain why numerical simulation is so central to your studies?

In the 1990s, numerical simulations became widely available to engineers in industry through the rapid development of powerful computers. They give us a unique insight into the flow of fluids, acquiring information for every location in the section considered. Measurements provide information in limited areas, and the engineer extrapolates these data to the rest of the region of interest.

Numerical simulations involve models to account for processes that are too complex to be simulated in detail, such as turbulence. Thus, the results are only an approximation of real flow behaviour. For validation, we employ optical measurement techniques like laser Doppler anemometry and particle image velocimetry.

You have been involved in developing solutions for hydraulic power plants, where you applied a method to predict erosion. What are the benefits of numerical simulation in this context?

I have worked on abrasion prediction and testing new coatings to reduce abrasion in hydraulic machinery for some years. My task was to deduce from abrasion patterns and analytically calculated velocity profiles how the abrasion process takes place in a controlled test

environment. This included some guesswork, but numerical simulation provided insight into the process of abrasion in real situations.

How does your foreign matter detector improve on existing cotton processing devices?

Cotton is delivered from fields in bales containing vegetable matter and other unwanted particles. It is fluffed up and carried with these foreign particles through a wide channel by an air stream at a velocity of about 15 ms-1. A detection unit identifies foreign particles and controls a row of removal nozzles distributed along the width of the channel. The unit can discern particles the size of a human hair.

We analysed the fluid flow around the area of the nozzle, which includes flow phenomena from the unsteady air jet and the path of the particle. Based on this analysis, the area’s design was adjusted to achieve an optimal removal process, facilitating the production of flawless yarn.

In a different project, you contributed to efforts to reduce train noise emissions. How did you employ numerical flow simulations in this project?

When a train travels at high speed, noise becomes a problem for the driver. We simulated the fluid flow around the rear-view mirror in order to locate where it detaches and forms vortices. These vortices lead to periodic pressure oscillations and, in turn, audible noise. We aimed to optimise the mirror’s design to reduce pressure oscillations and hence noise inside the cabin.

For validation, we carried out test runs with a real train travelling on a long straight piece of track. Noise level inside the cabin was compared for the original mirror and the optimised design, produced with a 3D printer. The optimised design reduced noise.

Everything flows

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Fluid translationResearchers from the Institute of Energy Systems and Fluid Engineering at Zurich University of Applied Sciences, Switzerland, are applying their expertise in the field of fluid dynamics to improve industrial processes, manufacturing and energy efficiency

Throughout his career, Lang has worked to provide

solutions for complex engineering challenges

FLUID DYNAMICS, THE subdiscipline of fluid mechanics concerning fluid flow, is applicable to a vast range of situations and processes, from questions of engineering and transport to the prediction of weather patterns. Some principles of fluid dynamics are even exploited for use in traffic engineering, with traffic being treated as a continuous fluid. Energy efficiency and the efficiency of various processes can also be improved via fluid dynamics. Therefore, research in this field has considerable impact on daily lives.

Since 2001, Professor Egon Lang has been based at Zurich University of Applied Sciences (ZHAW). Lang’s diverse portfolio of fluid dynamics research conducted while at various institutions, including Imperial College London’s Aeronautics Department in the UK and the engineering firm Sulzer, demonstrates the extensive scope of this field.

PROVIDING SOLUTIONS

Throughout his career, Lang has worked to provide solutions for complex engineering challenges. His PhD research focused on preventing the potential hazards that can arise during the transportation of gas in high-pressure pipelines, the results of which were published in 1991 in the Journal of Applied Mathematics and Sciences. Pipelines used to supply centres of demand with natural gas can be up to 200 km in length, with gas travelling at very high pressure (up to 150 bar) but low velocity (between 10 and 20 ms-

1). Due to these properties, each segment of pipeline contains a large amount of gas, and many of the gases transported in this way are either explosive or pollutants if released

into the atmosphere. A break in the pipeline could thus be a great risk to the environment and affected population. Lang was able to demonstrate that using a spectral method to investigate fluid flow following a rupture is a stable, feasible means of predicting and coping with potential hazards. After completion of the project, Lang went on to work at the Institute of Fluid Dynamics (ETHZ), where he transferred these results to a software program, which was subsequently purchased by a range of companies.

Building on this early success, Lang went on to work at Sulzer, an international engineering firm founded in Switzerland in 1834, in their R&D department. He remembers this period of his career as one ripe with innovation. There, he carried out several key studies, the results of which were invaluable to colleagues in production as well as the wider scientific community.

One such project at Sulzer exploited numerical simulation. Lang aimed to ascertain whether a static mixer provides optimal mixing and to test the validity of numerical simulation as a design tool for mixers. Again, this was a project with wide-ranging industrial relevance, as the mixing of fluids (either possessing different compositions or at different temperatures) is one of the most common operations in the process industry. For this study, Lang and his team wanted to test the Sulzer SMV static mixer and its efficacy in a denitrification facility. He explains that the relative complexity of Sulzer’s mixer made it difficult to analyse, but the project was a success: “After being able to generate grids for numerical simulation it was possible

to optimise the design to achieve better mixing performances or develop a new mixer with reduced cost”. This 1995 investigation also demonstrated that the static mixer materials vary in temperature and velocity in a denitrification facility.

PREDICTIONS

Four years later, Lang turned his attention to renewable energy sources, notably hydropower. The energy market’s ever-increasing demand for electricity led to intensified exploitation of renewable sources. Thus, even water resources with high particle content were sought. Lang and his colleagues at Sulzer – Reiner Mack and Peter Drtina – investigated the possibility of numerically predicting erosion in hydraulic turbines due to particles. They hoped that devising a method to predict the erosion that certain configurations

Measured velocities of the evolving air jet to remove foreign particles. Red areas represent high velocities.

PROFESSOR EGON LANG

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Cotton fluff containing foreign particles ejected by air jets.

ZURICH UNIVERSITY OF APPLIED SCIENCES: INSTITUTE OF ENERGY SYSTEMS AND FLUID ENGINEERING

OBJECTIVES

• To concentrate on unsteady fluid dynamics problems; for example, simulating fluid flow around a human head to detected possible noise sources that could influence the performance of hearing aids

• To collaborate with colleagues in optimising energy efficiency if fluid flow plays an important role

KEY COLLABORATORS

Professor Dr Thomas Hocker; Rolf Weiss; Pascal Diggelmann; Robert Epp, Zurich University of Applied Sciences, Switzerland

FUNDING

Commission for Technology and Innovation (CTI)

CONTACT

Professor Egon Lang Deputy Dean, School of Engineering Head of Mechanical Engineering, Energy Technology and Aviation

Zurich University of Applied Sciences School of Engineering Technikumstrasse 9 8400 Winterthur Switzerland

T +41 589 347 520 E lang@zhaw.ch

PROFESSOR EGON LANG obtained his PhD from the Swiss Federal Institute of Technology (ETH) in Zurich. He worked as a postdoc at the Aeronautics Department of Imperial College London, UK, and then spent 12 years at the R&D department of Sulzer working on fluid flow problems concerning left ventricle-assist devices, heart valves, mixing devices, atomising devices and the abrasion of hydraulic machinery. Since 2001, he has been at Zurich University of Applied Science investigating problems involving optimising the pouring process of beverage cartons, reducing noise from train rear-view mirrors and improving a foreign matter detector for cotton processing.

would incur would enable the design and production of a more resilient turbine. Their studies focused on guide vanes and labyrinth seals, and they noted how particle velocity and angle of impact influenced abrasion. Numerical simulation and field tests gave comparative results, notably that particle size strongly influenced the rate of abrasion. This correlation meant that industry stakeholders could use numerical simulation in a predictive capacity, which could aid designers in creating new optimised prototypes.

OPTIMISATION AND EFFICIENCY

Now at ZHAW, Lang continues to work in close collaboration with industry as a member of the Institute for Energy Systems and Fluid Engineering (IEFE). The Institute exploits expertise in the fields of fluid dynamics and thermodynamics to assist partners and customers in the design and production of their processes and products.

The words ‘optimisation’ and ‘efficiency’ characterise IEFE’s vision and its role in the development of diverse projects. As in Lang’s previous work, IEFE makes use of simulation and models, first to analyse current process efficiency and then to design optimised processes. This approach is highly economically viable, saving partner companies money even before the optimised processes and products have been rolled out.

MATERIAL WORLD

Although Lang no longer works exclusively in industry, his projects are still varied. The optimisation of cotton purification processes, which he investigated recently, is a project that quite literally affects everyday lives. Some manufacturers expressed disappointment at not being able to remove all foreign matter from harvested cotton before processing it into yarn. By analysing the original process and equipment, Lang and his team used simulations and particle image velocimetry to design an optimised system, featuring more efficient nozzles to blow out impurities. These new nozzles greatly improved the regularity of the airflow through the purification tunnel, making it easier to control and target unwanted matter. The optimised detection and removal process led to cotton with enhanced purity compared to the original samples.

DIVERSE APPLICATIONS

Fluid dynamics is also vital to developments in the transport industry. Recently, Lang’s research improved the aerodynamic form of train wing mirrors. When a train is travelling at certain speeds, oscillation of fluids around a wing mirror can create a great deal of noise and distract the driver. Simulation of the fluid flow and physical experimental evidence taken from a real train showed the team where to make aerodynamic improvements. A prototype based on these improvements proved successful in reducing noise.

Of all the projects that Lang and his co-workers have worked on at IEFE, the one that is perhaps closest to home is a project whose aim was to optimise the pouring process of beverage containers, such as orange juice cartons. After analysing how fluid flowed out of the original design, Lang was able to develop an improved opener. This makes for a much smoother, more reliable pour, with less risk of spillage. The company Lang produced this design for has since patented the new opener: he hopes it will be on a breakfast table near you soon.

INTELLIGENCE

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