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NATIONAL ADVISORY GCOMMITTEE FOR AERONAUTICS ;-’F5=#-

WAR’’IME luwolrrORIGINALLY ISSUED

February 1945 asMemorandum Report E5B1O

THE EFFECT OF COMPRESSION RATIO ON KNOCK IJMITS OF

HIGH-PERFORMANCE FUELS IN A CFR ENGINE

III - BLENDS OF 2,3-DIMETHYLPENTANE WITH 28-R

By Henry E. Alquist and Leonard K. Tower

Aircraft Engine Research LaboratoryCleveland, Ohio

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WASHINGTON

NACA WARTIME REPORTS are reprints of papers origimlly issued to provide rapid distribution of

10

advance research results to an authorized group requiring them for the war effort. They were pre-viously held under a security status but are now unclassified. Some of these reports were not tech-dcally edited. All have been reproduced without change in order to expedite general distribution.

E-252

https://ntrs.nasa.gov/search.jsp?R=19930093469 2020-02-23T00:31:56+00:00Z

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HACA MR MO ● I581O . ....- -----...-—--— .-._.___qgqi’yili]lll:

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HATIONAL ~RY comITTEE lNJRAEROIWWTIES

Ml!M3RmmOM RE20RI?————

for the

Amy Alr Forces, Air Technical Service Command

THE EFIH!ZTOr COMPIWSIXXV RATID 011KNOCK LIMI!lSOF

HIEH-EE131K)lMANCEFUEIS II! A CFR EHGIIIE

III - BLEIIDSOF 2,3-D~ WITH 28-R

By Henry E. Alqtist and Leonard K. Tower

SUMMARY

The kncck-15mlted perfomeace of hlmils of O, 50, and 100 percentby volume of 2,3-dimethylpentane in 23-R fwl waa datemincd with amodlfiod F-4 engine at three sets of conditions varying from severe tomild at each of three compreaaion rntloa (6.0, 8.0, and 10.0). Thelm.ock-llmitedperformancee of 2~3-dimathylpentanela shown to haveabout the same aemitlvity to cmpraaaicn ratio and Iiist-air tam-poraturc aa 28-R fuel. For W the conditions tested the lmoclr-ldmlted performance of 2,5-dimethylpentaneramgea from 12 to 47 per-cent (average of 23 percent) higher than that of 28-R fuel.

13WRODlXJT3DN

At the request of the Army Air Forces, Air Technical SemiteCcmunand,a general.program 10 being conducted at the Cleveland labo-ratory of the KACA to Investigate.the Jmcck-llmited perfommnc eofaselected group of aviation fuel caupcnenta In relation to triptana(2,2,3-trhuethylbutena). (See reference 1.) Several.hydrocarbons ‘are produced as byproducts or Impurities In one of the proceasea ofmanufacturhg triptano.- These hydrocarbons, if left In the finalproduct, would matirlelly Increaae the production of trlptana. Itla the purpcae.of thla report and of p@ II (reference 2) to deter-mine the antllmock effectiveness of two of these hydrocarbons,2,3-dhsthylpentana and 2,2 ,3-trlmathylpentana,over a wide range ofengine Variables.

The teata reported hereti, which present the relative effectsof cmpresslcn ratio and jmlet-air temperature on the Imcck-limltedperformance of 2,3-d.lmethylpentana,ware conhcted during Novmber1944.

.

2

APPARATUSAND TEST PROCEDURE

MAOAMR NO. P581O

The knock-lhlted perf Lomance of .2j3-dhethylpentane wasobtained on a modified F-4 eugiue with the auxiliery knock-testingequipment UE06 for the teeta reported in references 1 and 2. Ihtawero obtained at compression ratios of 6.0, t?.0,and 10.0 for eachof the folkwlng sets of operat~ conditions:

Condition M1.et-air tom- Coolant tern- Spark advariceperatum peraturo (deg B.T.C .)

(w) (%)

1 (severe) 2Z 375 452 (medium) 250 =0 30:3(mild) 1.50 250 30

Other engine conditions correspond to specificationCI?2-F-4-443.On the seineday, blends of O, 50, and 100 percent by volume2,3-dlmethylpentanewith 28-R were tested at one of the three ccun-pression ratios and a eingle operating condition.

DISCUSSIO1’JOF =TS

The lmock-limlted performance data for blends of O, 50, and100 percent 2,3-dlmo~-lpentcne ere prssmdmd In figures 1, 2, and3 for compression ratioe of 6.0, 8.0, and 10.0, reapectivel.y.Parts (a), (b), and (c) of these figures contain data at condi-tions 1, 2, emd 3. A comparison of the data for 28-R and2,3-dh&hylpentane plus 4.53 ti ~ per gallon indicates that bothfuels have slmllar characteristics ulth respect to lmock-llmltedperformance. Tho curves of lmock-limlted Indicated mean effectivepressure against fuel-alrratio of the two fuels uere”roughlypar-allel over the entire fuel-air-ratio range at all conditions tested.

The effect of compression ratio on the lmock-limlted performanceof the test blends is summarized in table I. The average knock-limlted performance of 2,3-dimethylpentan~is about 23 percent highsrthan the knock-llmited performance of 28-R fusl. In certain cases anIncrease of ccmpmssion ratio frcun6.0 to 10.0 resulted In a decreased.antllmockeffectiveness of 2,3-dimethylpentane. TMs decrease was notso apparent as.for triptane and 2,2,3-trlmthylpentane, partly because& lmock-lhltsd power attained with 2J+hthy@3n* at low cm:presshn ratioe and moderate operatimg conditions uasmuch lower thanthat obtabed with 2,2,3-trimethylpentaneor triptane. Table II shovsthe effect of Inlet-air temperature on the knock limits of blends con-taining 2,3-dlmothylpentaneand 28-R fuel at three compression mtlos.

. ..- -.-— .— -.——. . —.

X?AOAi4RHO. IEB1O 3

Except at a cm@reesion mtio of 10.0 end lean fuel-air I&rturo13;thoaeneitivittes of 28-R fuel emd 2,3-dlme~lpcnt~ to inlet-air tcuu-perature ware about the serne.

The &tit &unfi@res 1, 2, and 3 were cross-plotted in figuzw 4as compression ratio against knock-llmited Indicated mean effectiveprem’ure”. 5“s figure graphically aununarizesthe Imock-llmltmd per-formmm% data of 28-R and 2,3-dimethylpentanechow@ both fuels tobe slmllarl.yaffected by cm ssion ratio. Similar plots presentedIn references 1 and 2 Indicated that trlptane snd 2,2,3-trlme-thyl-pontane were much more seu.eltlveto oompresslon ratio than 28-R fhel.

A general.indication of the relative merits of trlptane,2,2,3-trlmetlqvlpentane;and 2,3-dtit@lpcntane as functiom of com-pression ratio is given in figure 5 at condltlon 2 (medlwu) and afuel-air ratio of 0.065. A laok of data provented coqparlEIoneatother fuel-alr ratloa. The averago tick-limited Indicated meaneffective pressureQ obtalncd with trlptano, 2,2,3-trimethylpentaneOand 2,3-dimethylpentanewere re~ectivoly 124, 98, and 23 porccntgreater than that obtained with 7X3-Rfuel; 2,3-dlmethylpentaneand28-R do have the advantage, howmver, of a lower sensitivity to engheseverity.

87JMW7Y OF RIISULT6

The results of knock-llm.itedtests of 0, 50, und 100 percentblends of 2,3-dimethylpentaneand 28-R fuel In a modified F-4 eng-under three operat~ conditions at compression ratios of 6.0, 8.0,Snalo.o are s~ Izeti as follows:

1. T2heImock-llmlted perfonnanc e of 2J3-Mmethylpentane hadabout the seinesensitivity to compression ratio and Inlet-airtaqperature as 28-R fuel.

2. For all the conditions tested the knock-llmlted performanceof 2,3-dimethylpentaneranges from 12 to 47 percent (average of23 percent) higher than that of 28-R fuel.

Aircraft Eoglne Resosrch Laboratory,.. National Advlso~ Camlttoci for Aeronautics,

Clevel.emd,Ohio, February 10, 19&.

. .. . .—. —— -. ...

4 lWCAMRl?o. E5B1O

REmImcml

1. Alquist, Hmry E., and Tower, Leonard K.: The Effect of Ccm-presalon Ratio on ~ck LMts of Hi@-Perfomance Fuels in a

“ C.~ Engine. I - BloI& of TriFtane end 28-R Fuel. NACAm No. TAJ1O, 1944 ●

2. Alquist, Henry E., and Tower, Lmnerd K.: The Effect of Com-pression Ratio on -ck LMts of High-Performance l?uelsin aCFR Engine. II - Blends of 2,2,3-TW.methylpentanewith 28-R.NACA ~ MOO =~~, 1~=. ‘

TM?lJII-I!TEWXOl! (XXWWBSIONRATIOCi’1‘THE~OCK LIMITSOF BIi@NDSCONIXWllG

iondltim 1: 1inlet-alrte~perature, 2259 F; coolant temperature,375° F;spark advance,45° B.T.C.

condition2:

1

~=Oo F; coolant temperature,250° F;inlet-airtemperature,.Jspark advance,30° B.T.C.

condition3: inlet-airtemperature,150° F; c~olant temperature,250° F;s~k advance, 30° B.T.C.

Percentage imp ratiob2,3-dimetbyl- r/A = ().0625 r/A = ().()7(3 F/A = 0.090 F/A = 0.110pentane infinal Menda Conalthn Ccildlt1an Conaitixl Condltlhn

1213 1123 123 1!23

Comressionratio. 6.0

0 11.~ l.fx) 1.(X3 1.00 1.()() 1:00 ‘1.00 1.0011.00 1.00 1.00 1.0050 1.09 1.13 1.13 1.10 1.14 1.15 Z.lo 1.11 1.13 1.07 1.07 1.09100 I1.21 1.29 1.29 1.27 1.26 1.30 1.20 1.20,1.221.17 1.20 1.13

cm.pressim ratio, 8.0

0 1.00 1.00 1.00 ?..0(2!..001.00 1.00 1.00 1.00 1.00 1.00 1.0050 1.17 1.15 1.12 1.20 1.13 1.11 1.21 1.13 1.10 1.09 1.09 1.09100 1.33 1.23 1.26 1.47 1.26 1.23 1.36 1.23 1.22 1.15 1.24 1.20

cm.presslmratl~, 1!).9

o 1.00 logo 1.00 1.00 1.0011.001.0!)1.00 1.00 1.00 1.00’1.0050 I I

1.00 1.04 1.13 1.90 1.02 1.12 1.00 1.1.11.10 1.05 1.07 1.11100 1.12 1.1711.281.15 1.16 1.25 1.28 1.22 1.21 1.21 1.18 1.19

%eadconcentrathn, approxlmatel.y4.53 ml TEL/@.blmep ratis . imp of blend/lmepof 28-R fuel.

NationalAdvisory,Cmmltteefor Aeroqau%ics

—

I

T.K6LEII - FFl?XCTOF INLET-AIRTEMPJMTURE M THE KNOCK LIMITS OF lZWiDS

CONTAINING2,3-DIMETHYLP~~ AND 28-R F-UELXl?THREE CWPRESSION RATIOS

[F-4 ensti operat~ at mild an~ med~-zuc,nd~ticns: inlet-ai~tmqxmatvres,150° F and 250° F; caolant temperature,250° F; spark advance,30° B.T.C~

Percentage F/A = 0.0625 F/A = 0.CJ70 F/A = 0.080 F/A= 0.090

2,3-dimethyl-~p ~p imp imep ImepI‘tiep lmep imp

pentane infinal lllenda

ratlob differ- ratiDb dlffm- ratiab dlffer- ratlob differ-ence encec Oncec encec

CampresslJnratla, 6.9

@ 1.22 ‘ 39 1.:4I ;: I 1“1022 1.C5 12

’50 1.22 45 1.15 1.11 29 1.07 10100 1.22 I 50 1.17 I 4; 1.U 30 1.07 20

Cxnpreesionrath= i3.O

o 1.13 20 11.15 24 1.11 20 1.06 125i) 1.12 21 ‘ 1.13 23 1.07 15 1.03 7100 1.18 35 1.12 24 1.10 21 1.06 13

. Cmpreoslon ratio, 10.0

0 1.33 32 1.33 33 1.31 35 1.28 3650 1.45 46 1.48 49 1.36 M 1.27 39100 1.45 52 lo4~ ,WCz 1.39 53 1.26 42

?Lead concentration,appr=:~tely 4.:3 ml Tl?L/gal.bimep ratio . Imep at 150°F/tiep at 250aF.Cimep difference. Imep at 150°F - imep at 25003’.

Natimal fldvism~ Comitteefor AeronautIce

cm”“

ACA MR MO. E5610To , ,, ,, ,,, 1,m ,r , iN~llOjuuADVISORY

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COMiTfiE FOR AERONAUTICS

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Fuel-air ratio(a) Inlet-air temperature, za5° F: coolant temperature, 375° F; spark advance, 45° B.T. O.Figure 1. - Knock-limlted Wrfonaanoe of blends of 2,3-dlmethylpentane end 2!J-Rfuel

CS’Rengine at compression ratio of 6.o. Engine speed, lW rpm; oil temperature,:250 r.

.-. .—

.----

NACA MR NO. E56i0

80NATIONAL AOVISORY

, ,

: :“ CMITTEE FOR AERONAUTICS

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(b) hlet-air tamerature, @ ~; ooolant t-eratures =@ ~; s-k advanoe. 30° B.T. C.?Igure 1. - Continued.

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COhUITTEE FOR AERONAUTICS

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(o) Inlet-alr temperate=, 150° F; coolant temperature, Z50° F; spark advance, JO” B.T. C.Figure 1. - Concluded.

NACA MR ~0. E5B1050 e , , v , , 1, ~rt , r 1111 , I , , 1

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5’R engine at compression ratio of 8.0. Enslne epeed, Moo rpm; oil temperature,1650 E’.

NACA MR NOC E5810

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160NATIWA& ADVISORY

COWITTEE FOR AERONAUTICS

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—(-

b) Inlet-air temperature, 250° ~; coolant temperature, 2soo F; spark adv~ce. 3o0 B.TOC.Figure 2. - Continued.

HACA MR t(o. E5BI0l.1.lty v , 1

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l–

NA CA MR tto. E5B10NATl@4AL ADVISORY

COMMITTEE FOR AERONAUTICS

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------------?lgure 3. - ‘-–fro-&-i~it~”p&hmance of bienas or-2; %dim+61_

~ engine at ompresslca ratio Or 10.0. Engine speed, lgOO rpm; oil temperature,?60 r.

l—--- .— ——.

NACA MR No. E5BI0

, r 11 r, ,,,NATIONAL ADVISORY

, , , r 1 r 11 , 1 , 1 I 11 I I I 1I 11 r , t I

COMMITTEE FOR AERONNJTICS

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m765 .06 .07 .08 .09 .10 .11 .12

Fuel-alr ratio(b) hlet-~i;ogyng~:we, 2500 F; coolant temperature, 50° F; spark advanoe, >0° B.T.C.Figure 3.

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Fuel-ah ratio(C) hlet-~h~~jx~ure, UC@ F; coo-t t=iperature, 250° F; sperk advanoe, W“ B.T. C.Figure 3.

I

NATIONAL AOVISORYCOhWITTEE FOR AERONAUTICS

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~ \\ \

f-l\

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\~

\0% \\ \ \\ . \ Percentages denote volumetric

dconcentration of 2,3-

\ % \6

dlmethylpentane + 4.53

al\ L\ \ ml TEL\gal In 28-R fuel.

vA:F-I

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x

6 6.5 7 705 8 8.5 9 9.5 10

(a) Inlet-air temperature,Compression ratio

22s0 F; coolant temperature, 3750 F; sWrk advance, 45° B.T.C.Figure 4. - Effect of compression ratio on knook-limited perrorm~ncs of 0, 50, and100 percent 2,>dlmet@lpentane in 2g-R fuel at fuel-air ratios of 0.062 and 0.090.Engine speed, 1800 rpm; oil temperature, 165o F.

zo.

I

32GNATIONAL AOVISORY

COMtlTTEE FOR AERONAUTICS Fuel-airratio

—0.062280“- --- . ------ .090

-- Condition 2 (medium)

6-” ‘-- .-

. - .-

- Percentages denote volumetric●

\-- \

\ -~ concentration of 2,3-

:2&o “- ciimethylpentane + 4.53\ %

# % \ \ \ ml TEL\~al in 28-R fuel.

1

●

6 6.5 7 7.5 l!J g.s 9 9.5 10

(b) Inlet-air temperature, 2sO°F;Compression ratio

coolant temperature, 2sOo F; spark advance, 300 B.T.C~Figure 4. - Continued.

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150° F; ooolant temperature, PjOo F: spark advance, ~0° B.T.C. ~Figure 4. - Concluded. m

a

..

NACA

f+~

30

MR NO* E5810NATIONAL JWVISORY

COMMITTEE FOR AERONAUTICS

,0“Fuel component

*Triptane (2,2,~-trimethylbutane)

+ 4.53 ml TEL/gal——— —

2.6 ;2,2,~-Trlmethylpentane + 4.53 ml

TEL/gal\\\ — 2,~-Dimethylpentane + 4.53 ml\ TEL/gal

2.2 \\ % \ Condition 2 (medium)

x \Fuel-air ratio, 0.065

..

\\ \ \ \

1.4 :% \ .

P

s-65 :1.0:’’” a1 a, , h ,1,, 1 a1 ,aa B.,, , 1. ,1&a a *1 ,

6 a 10Compression ratio

Figure 5. - A comparison of the effectiveness of triptane, 2,2,~-trimethylpentane, and 2,3-dimethylpentane relative to 2g-R fuel.Inlet-air temperature, 2sOo F; coolant temperature, 250° F; sparkadvance, 300 B.T.C.; engine speed, 1800 rpm; oil temperature, 165° F.Data for trlptane and 2,2,~-trimethylpentane taken from reference1 and 28 respectively.

I