REPORT NO. 812

KNOCK-LIMITED PERFORMANCE OF SEVERAL INTERNAL COOLANTSBy DONALD R. BE~N and JOHN C. EWASD

SUMMARY

17M ej%eciof internal cooling on the knock-iimited perforna-ance of AN–F–H fuel was investigated in a CFR en~”ne, andthe foUowing infernal coohnts were used: (1) water, (2) methylalcohol -water mirture, (3] ammonia-methyl alcohol-watermixture, (4) monomethylamine-water nmrture, (6) dimetl@a-mine -water mixture, and (6) trimethylamine-water mixture.The internal “Coolant$were injected in the ti”o of )4pawndper pound of AAT-F-2?8 fuel. Test$ were run at inlet-airtemperatures of 160° and %0° F to indicate the temperaturesenm-ti”uityof the internal+molant ~olutimw.

In thig inredigation the me of methyl aJcohol-unrter, mono-methylamine-water, and dimethylamine-water mixtures as in-ternal coolants raised the knock limit more than did water alone.The additwn of ammonia to th methyl alcohol-water mixturelowered itg knock-inhibiting e$ectg. For mod fuel-air ratios,the h-imethylamine-water mixture decreased the knock-limitedpower.

EKTRODUCTION

This report presents the results of tests carried out todetermine the effect of severaI viater+oluble internal cooIantsupon the knock-liited performance of LIT–F–28 fuel.These tests are pm-t of a general investigation of internaIcooling of internal-combustion engines and were conductedat the NACA Clevehmd laboratory in May and June 1943.

ENGLNE AND AUXILIARY EQUIPMENT

Apparatus,-The tests were performed on a high-speedsupercharged CFR engine coupled to a 100-horsepower,direct-current-, cradle-type dynamometer and equipped withan aluminum piston, sodium-cooIed exhaust and intakemdves, and a cylinder with four spark-pIug holes in the head.Knock was detected on a cathode-ray osdloscope in con-junction with a magnetostriction pickup unit. All tem-peratures were measured by iron-constantan thermocouplesand a df-balancing potentiometer. The arrangement ofthe spark phgs and knock indicator is sho-ivnin @ure 1.

Determination of air fLow.-The air flow for idet-airpreawres below 120 inches of mercury a.bscdutewas measuredby a standard orifice and manometer or pressure-gage system.The air flow for inlet-air pressures higher than 120 inches ofmercury absolute was calculated by straight-line e.xtrapola-tion of the plot of idet+ir pressure against air flow. The

test was arbitrarily stopped when the inlet-air pressurereached 150 inches of mercury abscdute. Figure 2 showsthe schematic diagram of the inIet-air system.

Injection of fuel and internal coolant.—The fueI was in-jected by a high-pressure injection pump into a modifiedAFD 3-C inlet manifold paraIIeI to the flow of air. Figure3 is a s~hematic diagram of the fuel system.

The internal cooIant was continuously injected at roomtemperature into the injection elbow just above the fuelinjection nozzIe and padel to the air flow. A standard _._._.AFD 3–C idet manifoId was modified to permit this sepa-rate entry. The schematic diagram of the internakoolantsystem is shown in figure 4.

,-.-BankP@

.—

\FmmE I.—Laatfon r4 qwk plugs and knock pkkmp tmdt in CFR cyhder.

PROCEDURE

All the data presented in this report are knock-limited.The range of operation was limited (1) by an artificial limitof 150 inches of mercury absolute in the inlet-air pressure,(2) by a ma.x.imumfueI flow of 30 pounds per hour, or (3) bypreignition. In some cases spark-plug failure with concomi-tant preignition caused temporary shutdowns. If surfaceignition occurred (usurdlyobserved as continuous afterfiring),the knock-limited data were recorded and the data points

89

https://ntrs.nasa.gov/search.jsp?R=19930091890 2020-08-04T14:12:27+00:00Z

90 REPORT NO. 8 12—NATIONAfJ ADVISORY COMMITTEE FOR AERONAUTICS

N‘“

A, #.lerDIO13XIpk2 K, opm!ng for fntemal-eoobmt-injwtionB, a[r-meaaurfng orffi%C, preamre gageD, afr-pmesure regulatorE, dial thermometerF, air preheaterG,mrrgetankH, flexible eauplfng1, engine oylfnderJ, Met mmdfold

nozzleL, openfng for fuel-InJeetlon nodeM, pressure gageN, afr supplyCS, rnrmometmP, pilot valvea for preaaure regulatorQ, auxfflary pflot vafva ,R, pressure gage

Fmum 2.-Dfasramof Inlet-ah ayetem.

/’%---”’

H-

A, fueI aapply tankB, eocdorC, primary fuel pumpD, atrafnerE, adenoid valvaaF, prcwure gageG, pmssnm relief valve

u

H, fuel-wefghfng etand1, fuel-fnjeetion nozzleJ, rotameterK, enrge eIlmfnatorL, hlj12CtkXlpIIIIIPM, flfterN, OfrCUlatfIISPUDIP

FmuR~$.–D@.ram of fud sYS@rrL,

were labeled “surface ignition.” They arc shown as solidpoints on the curves of variation of indicated mmn cffcctivopressure and inlet-air pressure with fuel-air ratio. Tl~Gfollowing engine conditions were maintained constant:

Engine speed, ~m---------------------------------------- MM

Cbmpra&~on ratio ---------------------------------------- 7.0

Met-coolant temperature, 0 F----------------------------- MOInlet-air temperature, 0 F--------------------------------- 150,250Spark advance, deg B. T. C.---------. --------— ---------- 30

Oil temperature, 0 F------- .--. ----- .---. ---... —---------- 150

—

●

T“

Y,/13’-

D

G/’

,’

A, oonnaetlon to air wpplg F, internal-euokmt storage tankB, internal+@ant-tr@tlon nozzle G, -onh storege tadC, ccbder H, control valroD, oomectlon to exhauet MM 1, rotormterE, filter J, chwlatlng pump

FIQUPJ 4.—Dfagnrm of Internal@darrt InJcctlon syatcm.

The internal coolanta were added in the ratio of !4 poundper pound of fuel as measured by a special rotmneler. Asingle lot of AN-F–28 fuel was used for tho entire investi-gation. The following intwnal coolants wcro investigated:

1. Water2. A mixture of 70-percent teclmical methyl alcohol plus

30-percent water by volume3. A mixture of 70-percenL technical methyl alcohol plus

30-percent water by volume, emmentratwl with tinhydrousammonia to 30-percent ammonia by weight of the find ‘-solution

4. A mixture of 32-percent commercial monomethyIaminoplus 6&pcrcent water by weight

KNOCK-LJMI~” PERFORMANCE

5. A mixture of 26-percent commercial dimethyhunineplus 74-percent water by weight

6. A mixture of 29-percent commercial trimethykminepIus 71-percent water by weight

some of the properties of the amine achtions are listed intabIe I.

TABLE I

SUMMARY OF CHE3iICAL AND PHYSICAL PROPERTIES OF

AMINEWATER SOLUTIONS

4 M&n&m~:y~m ime- 32 0.43 Ne@Ire_ Ne#ati~e.- -4a

5 DmtiW~le&nter !26 .939 -.._do_... Trace ---- -0.4

6 T1’fmeWIamhlWmter 20 .967 _._do- _—_do--- r?toso.mIxture.

During the course of each test, the variation of rotameterreading (fueI flow) with Met-air pressure (air flow) wasdrawn. This pIot gave an immediate indication of the cor-rectness of each knock-limited point. Before each interredcoolant was tested, two points in the rich region for the fueltdone were checked on the plot of inlet-air preesure as a func-tion of rotameter reading. This check indicated whetherthe engine was operating satisfactorily. For each set ofdata, the check pIots of fueI flow (fuel-weighing stand)againstfuel rotameter reading and air flow against inlet-airpressure were drawn. This procedure insured that boththe fueI measurement and the air-flow measurement wereconsistent.

The flow of the internaI coolant was measured by a specialaluminum-bob rotameter, the setting of which was deter-mined from the reading of the fuel rotameter. Both fuel andinternaLcooIant rotameters were calibrated over the entirerange by timing the flow of a specfied weight of each fuel orintwmrd coolant. When the internal-coolant scdution con-taining ammonia vms calibrated, the fluid from the rotameterwas emptied into an acid medium. This procedure neu-tralized the ammonia and minimized the weight 10ssdue tavolat.ility.

In the rich region the fueI flow and the internakdantflow were first fied before obtaining the knock point. Theair flow -wasincreased until incipient knock occurred. Inthe lean region the inlet-air pressure was first fixed; the fueland the internal coolant were then simultaneously increaseduntiI incipient knock occurred. Most of the points werechecked for pcssibIe afterfiring.

RESULTS AND DISCUSSION

Figures 5 (a) and 5 (b) compare, at an inlet-air tempera-ture of 250° F, the knock -bited performance of ANT–F–28fueI and AN–F–28 fueI PIUSeach of the following internrdcoolants: water, 70-30 percent by vohune te&nicaI methyIaIcohol-water solution, and the 70-30 percent by vohunetechnical methyI tdcohoI-water solution containing 30 per-cent ammonia by weight. “

If the relative power ratio is defined as the ratio of knock-

OF SEVERAL INTERNAL C~”IiANTS 91

Iimited indicated mean effective pressure obtained -with thefueI pIus the interred coolant to knock-limited indicatedmean effective pressureobtained with the fue[ aIone,at a fuel-air ratio of 0.06 the reIative power ratios for the three internalcoolants are 1.52, 1.59, and 1.47, respectively. At a fuel-airratio of 0.085, these reIative povier ratios are 1.34, 1.80, and1.65. .

The use of water improved the lean-mixture r~ponse con-siderably more than the rich. The addition of ammofia tothe methyl alcohoI - -watersduticm lowered the knock-limitedperformance over the entire range of fuel-air ratios. Waterraised the indicated specific fuel consumption, but the othercooIants lowered the fuel consumption at low fuel-air ratios.The addition of ammonia to the tdcoho]-water mixturepromoted surface ignition in the rich region.

The knocldiroited performance of the internaI coolants atan idet-air temperature of 150° F is compared in figures 5 (c)and 5 (d). At a fueI-airratio of 0.06, the reIative’power ratiosof water, tdcohol+vater, and ammonia-tdcohol-water mix-tures are 1.27, 1.68, and 1.29, respectively; whereas, at.a fuel-air ratio of 0.0S5, these values are 1.12, 1.59, and 1.49. Acomparison of figures 5 (a) and 5 (c) shows that a methylaIcohoI - water salution is highly temperature-sensitive.Strangely enough, addition of ammonia to this .saIutiondecreased its temperature sensitivity, and the curve shapewas more nearly the same at both temperatures. TheaIcohoI-water solution showed an extremeIy high lean-mix- .ture response at. an inlet-air temperature of 150° F. At afueI-air ratio of 0.043, the engine developed a knock-limitedindicated mean effecti~e pressure of 558 pounds per squareinch, accompanied by indicated speciEc fueI and liquidconsumption of 0.37 and 0.55 pound per indicated horse-power-hour, respectively. These consumption did notincrease rapidly in this very lean region. The engineshowed no tendency toward rough running.

The second group of internal cooIants compared include:7(Y3O percent by voIume technical methyl &ohoI - watersolution, a commercial 32–68 percent by weight monomethyl-amine+vater solution, a commercial 26–74 percent-by weightdimethylamine+ater solution, and a commercial 29–71 per-cent by weight trimethylamine-vrater scdution. Data show-ing the knock-limited performance at an inlet-air temperatureof 250° F of ANT–F–28fueI and ANT–F–28fuel plus each ofthese internal coolants are plotted in figures 6 (a) and 6 (b).At a fuel-air ratio of 0.06, the reIative power ratios of thesecocdants are 1.59, 1.81, 1.78, and 0.85, respectively. At afuel-air ratio of 0.085, the reIative power ratios are 1.80, 1.84,.2.04,and 0.83.

Both monomethykunine and dimethylamine showedmarked improvement over alcohol as knock suppr~o~.The monomethylamine showed better lean-ti~ture charac-teristics than the dimethyIamine, but the reverse was true inthe rich region. This reversal of order may have been dueto the fact that, in the rich region of the monomethyIaminecurve, continuous afterflring vms encountered; that is, theignition could be turned on or off with Iittle change in thepower output. Slight decreases of the power level belcw theknock point eliminated this surface ignition.

REPORT NO. 8 12—NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS

\ I

I I 1 I-n I I t 4 I I 1 1 4

{

9 u

/I I 1 I I I /

6fn+ernol cooionf

+’‘ ~injeafea’ B Ibjlb fuel)o None

I n Woterz o 70-90 percent (VOI) methyl oloohol-woter ,3 A SOJU tbn 2 canfoining s~peroent (wi~ ammaniu

Solid points indicof e SUPface ignitionn ///

\ ,

❑

L

Ea ~ /&

I

‘1 I 1“—FcrM+-/l&l I I / I

I

I I II

I I I /F I I I I I

(a)

-04 .05 .06 ,07 .08 .09 .10 .ft .12Fuel-ah rotlo

(u) Vsrfefion of Lodlmted .specfflofuel consumption and knock-llrnited Indfcsted mean effectlre pre.wure with fuekdr rstio at tnh+alr temperature O(2W F.

FIGURE5.—Effect of interns.1 ooslanta 1, 2, and 3 on !um&.lfmited SI@IM pstiwmIuI@. CFR OI@M; f@ AtJ.F.%; UMIIp~OII ~tlo, 7.w ~lel~bt tem~mtu~ W ~ sprkadvrmcq 33” l%T. C.; engine speed, 2.WIrpm.

KXOCK-I.IWITED PERFORMANCE OF SEYERAL INTERNAL COOIANTS.

(b) VoristIon of Indicated SLWCI13ClIqnId ccmsnrnptlon and komk-ltrnited inlet-ah PIWSIWI!with fuel-air mtIo at Irdel-air temperature of W F.

FIGrRL 6.--Conthued.

W3107-5L7

REPORT NO. 812—NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS

560

520

I

460\

A .% wv

~ Ao— - — — — — — —

A \ L b ~0

‘s 440 A:

.

~ A/

gm

~ 4iz7b& \

$A A

Ti, D

<

$360A AL

$ A

L

320

/

280 A \ / { \

~ m 4

:8

t In+ernol cocdon+

240 (injected % Ibjlb fuel)‘0 None

I ❑ titer

.7 Z? 0 70-30 peroent (voI) methyl alcohol- woter3 A Solutlon 2 wntoining W-per-oat (w+,) ammon ia

Solid @ints indicate surface ignition -

>,——

+= 10 k+“

$.

t

“~.5- E 2 ..

iw < v-

.4 ~

(c]

.3.04 .05 .G6 .07 .08 .09 .10 .fl t.?

Fuel-ah- ratio

(c) Verfat!enof !ndicated SPWMCfuel con.%nnption and knock-llmked Indfeated mean eflectire pressure with fud-afr rai[o at InIet-dr tcmpemturcof

.,

lW F.

IWOCIC-LIMITED PERFORMANCE OF SEVERAL INT’ERN.AII COOLKWS 95.

rmzm

c..$

+.E.<

180-

A & ‘

I I \r\Io I I

A“loo

L < - — ~ ~#— — — — — —

80 / -\ n

A/

<i\_ _ ~ -

:SM Q

o

40

hi8rnal coafcm +(ik@cted ~ I&/lb fuel)

o Nom’I n Wafer

2.0 70-30 percenf (voi] methyl alooho+wa@r3 A Solution 2 conf aining 3’Q-perceni (wf) umm onia

Solid poinfs indicate surface ignition

/.2

/

Lo P.

+ P 1

~

~ .8\

o-2 I

I

I I I h-ln I IK

.A-$71#’--

.- . .. —.— , I I 1 I

I I w“ I I

.4Y t

(d)

.04 .05 .06 .07 .m .09 .10 .fl .!2Fuel-air raf io

(d) Vtiim of indicated .wi& llqnid consumption and knock-tited InIetdr pressure with fnd-air ratio at Met-air tenllh?ratom or 16LF F.

FIGCEE5.-Condnded.

96 REPORT NO. 8 12—NATIONAL ADVISilRS- COMiIITTEE FOR AERONAUTICS

1

On the lean side of the curve, the monomethylamine-water test ..was arbitrarily stopped when the boost pressurereached 150 inches of mercury absolute. As with the methylalcohol - water mixture,no tenclency towtmduneven firing wasexpmienced. At a fuel-air ratio of 0.044, an indicated meaneflectivr pressure of 495 pounds pcr square inch was reached,TIJecorresponding indicated specific fuel and liquid consump-tion were 0.38 and 0.56 pound per indicatd homepower-hour, respect.iveIy.

TIM trimethylamine-watw mixture lowered the linock-limited performance of the fuel. All the aminw lowered theindicated specific fuel consumption, in some cases to anamount greater than can be explained by ccmsidering thecontributions of the interred coolant to the heat of com-bustion.

The knock-limited performance- data of the internalcoolants at an inlet-air temperature of 150° F are comparedin figures 6 (c) and 6 (d). At a fuel-air ratio of 0.049, thomonornethylamine allowed a knock-limited indicated meaneffective pressure of 620 pounds per square inch with indi-cated specific fuel and liquid consumptioris of 0.37 and 0.55pound per indicated horsepower-hour, respectively. Thisoutput amounted to 1.96 indicated horsepower per cubicinch of engine displacement.. ‘The occurrence of preignitionprevented tbc measurement of rich-mixture response. Thetemperature sensitivities as measured by the ratio of theindicated mean effective pressures at inlet-air temperaturesof 150° and 250° F of monomethylamine, ciimethyknnine!and trimethylamine were about the same. A limited supplyof dimethyIamine-water solution prevented completion ofthe rich-region response measurement.

The relative increase in the Imock-limited power obtainedwith the various internal-coolant mixtures for four differentfuel-air ratios is shown in table H. The temperature sensi-tivity of the inknal-coo]ant mixtures is presented in table111in which a comparison is made of the knock-limited powerobtained at inlet-air temperatures of 150° and 250° F.

TABLE IIIIIPROVEMENT IN l<NocI<-LIMITED ENGINE

PERFORMANCE OF AN-F-28FUEL ACHIEVED B1- INTERNAL COOLING

[CFR engfrw com~reaeion ratio, 7.0; Inlet-atr km2?4 F: spark ,dvmw, W“ B. T. ?%m?[ne sped, 2699r,rn]

ture, W T lnlet+oolrmt temwature,

Relative pxrer rtitlo

- Imep (fnel+lnternal coolant)Imev (fuel clone)

I IntermrI cootint(I@etcd )4 Ibflb fuel)

r-0.& o.WI——.

A’mle...........................................1 Water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . k!! L m)

1.522 Methyl alcohol - water mixture (7N0 pweent

by volume . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..- L61 1.39L4 Monomethy mine-water mlxtum (32+?SN-

mrrt by weight) . . . . . . . . . . . . . . . . . . . ----------- L% sL816 D!metb Iemlne-water mistoro (!w-74 pereent

I by we~ht) . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . ..- l.sz 1.78

● Afmrflrhg MCOUlltCred

IIO.(B O.oe

——

:OJ Lw1.2a

“LS4 1.i’s

*LS5 ~L83

1.% .-..—.

A plot of the knock-limitwl indicated mean M’cctivrpressure as a function of the inkt-tiir pressure aLan inlr[-tiirtemprrnture of 250° F is presented in figure 7 for AN- F-%fuel with and without cuch of t.h(’following internal coolants:water, 70-30 percent by volume mrtlqyl nlcohoi - wutcrsolution, a commcm-ial 32-68 percent by weight monomethylarnine-water solution, and a commercial 26-74 pw-cent by weight dimetl~ylamine-watursolution.

For a fixed inlet-uir prcasuro, the indicated mean ctktivcpressure--was roughly proportional to the fuel flow in theIean region; therefore, at- constant inlet-air pressurr theinternal coolant. thtit-allovmd thu highwt. knork-limited fudflow allowecl the greatest indicated nwan rffcctivc prwsurc.At an idet-air pressure of 150 inrhm of m(’rcury nbsolutr,the indicatid reran effective prwsums of alcohol and nlono-methylamine were 44S and 492 poun&s ptw squnrc inch,rcspectivcly, This effect would bu un importrtnt consider-ation if knock-Iimitecf km-mixture pwformmm were con-tempInted.

The trend of th i[ldicat.(’~i-meal~+?flt:ctiv(~I][’(*sllrecurvesin the rich region shows_that the indicntcd mmn cflvctiw

pressure‘was very nearly a straight-line function of lhr uirflow even though the fuel-tiir ratio and th~!intmnal roolnntswere varied. For a given knock-limitml indicatd mcnneffective pressure, lean-mixture opwa~ion rrquircs more nir

flow than rich-mixture operation. At a knock-limitedindicated mean &ect.ive prmsur(’ of 400 pounds pm squnn’inch, uchiwed by mollo]~~[’tl]yltil~~ille-~~’aic’rsolution, thrrich and Iean inlet.+ prcasurcs were 88 and 103 iuchw ofmercur~bsolut~, lr&prct ivc]y. Tl]P [*hoicc bc{~yccn riv]l-

mixture and lea.ri-tii.<ture operation would dopcnd upon thI1

balance between s~pcrchargw caparity nnd nllownblc fuelconsumption ‘m well as upon the uniformity of WV mixturedisbjbution in the lean region.

T.4BLI?111

EFFECT 01’IXLET-AIR TEMPERATURE

OX IIXOCIi-LIMITED ENGINE

PERFORlrAXCE 0)?AN-F-28 FUKI, USED IXCONJLliCTIOX WITH INTEIMA1. cOOLANTS

[CFR engtne; compression ratio, 7.LUlulet-eoolsnt tern waturc, 2W ~ sIrMk WIWWW,30° B. T. C.; engine FP.M, Z&pm]

- ‘ntwtim’unt““-==-l(Wrted JI Ib.rlbfuel)

Nmle.L.......................-.-.-.-.... ....lvatw . . . . . . . .._. .-- . . . . . . . . . . . . . . . . . . . . . . . . . .Methyl deohol-water mhturc ~ W pomont

x~+:~e~:~-~--fiii;-tirk-%:-

DIrnetb Iamhre-watei mj~ture-@-% ‘~$~~ -by”we~ht) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1.24 !. 16 L 32 1.xl. . . . . . . 1.23 1.11 Lw

L 46 1.57 L ‘x L 13

L 42 . . .... . . . . . . . . . . . . . . . . . . . .

1.42 ~L 81 . . . . . . . . . .._.--

. Aftrdrtng encountered at Sn Imletdr mnpemturc or 13WF

,IXA’OCIC-L1311TEDPERFOR3JXTCE OF SETEIL+LINTERNAL COOLANTS

,.97

@ VIM

FIiirEE 6.–Effect of

.4 ,

.3.04 .05 .06 .07 .08 .09 ./0 .11 .12

Fue i- uir rof io

+atkm of fndfcated sFwItlc fuel mnsmrrptian snd krmek.IImfte+i fnclfmted mean ef?ectire pmsmre wkh fnehtr ratio at frrk?t-sk terrr~mtnre r4 25(P F.

fntwmd coolants Z 4, 5, and 6 on knwk-lfrnited engine perfc+-msnw. CFR engfne: fneI, A,N-F-Z& compression raffi, 7.0; Ink?t-mrdant terWS@UR, * R SPMkwI’amee, W B. T. C.; er.@fneW !25Mrpm.

—

-—

REPORT NO:”812—NATIONAL ADVISORY C!OMMI’ITEEFOR AERONAUTICS

f60

Q b ..

3Q/40

?

e..

a’$ /20

‘1$:

QL“5 ,~~ ,i!*c.-:.

~so

4c1

g

60

e

40 -/.6—— — — ‘Y~/ ~

.— I

Internal coolant(inje.ied ~ lb~lb fuel) v

1.4 0 None -.

2 0 70-30 percent (vol) ?n@hyl oiaohol-wo +er /

4 v 32-66 percent (w f) monomefhylumine -water5 v 26-7+percen+ [wt) dime fhylamine -water

#

1.2

i~I

+1.0~

*“ /*--

n.Q

\

L m1--”I lx

d\ ‘{

Fuel-air ratio

(b) VwMlon of indicated SWOM3Cllqutd consumption and knock-lirnitcd inlet-nir prcmm-e with fueldr ratio at tnlct-air tem@wrdum of !kW F.

FIGURE6.—Corrtfnued.

KNOCK-LIMITED PERFORMANCE OF SEVKRAL INTERNAL COOLANTS

(c) Vti

640

1

600

560

r

e“;520 vw$ F

$I /

eVr

--480 I\

\ .-.:

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d.- ~“

k og 440G

q

300 /

1“A

0

-- ~

~ /

260 6- 1 k!

00

v

h

220:8 — )~v

/

1lnfemof coolanf

(injected B Ib/lb fuel) /

None{

2; 70-30 percent (voI) methyl afcatml -wafero

.7

I

4 v 32-66 percent (wf) monomefhylamine -wafer5 v 26-74 percenf (wt) dimethylomine - wafer 7 /6 v 29-7[ percent (wf) trfmefhylamine - wafer

Solid points indicate sutiace ignition

+ -=J u A

~ o

~ u.

~-<

M.. .4

/.

k/ ,

.4 VI <

w Q ev r

&*

o Vv

00 0 ~ -

(c]

.3.04 .05 .06 .07 .08 .09 .ia .If .1.2. Fuel-air ratio

ItIoncdIndfcstedsp+e(flcfnd consumption md kncek-llmlted indkated mean ef?ectlre pmasum with luck.h mtlo d Met* temp?ratura

FIQm 6.-Conth&ed.

99

C4Mr F.

100 REPORT h’O.S12 —NATIONAL ADVISORY COMMMTEE FOR AERONAUTICS-.

160

& > AL ~

3 *b j40 .

E’<>

c. .

.. 0.

g j~~

2u

kL

\

“~/00-.\

L<c

<$

@ 80

48&

60

40

(iqjected B Ib}lb fuel)o None”

20 70-90 peroen+(vol) methyl okohoi-wafer,4 v 92-60 peroent [w+) monomethylomine -wofer5 v 26-74 percent fwi) dime fhylamlne-wafer6 q 29-71 peraenf (wt) irimethylomine-wo+er

/.2 -Solid points Indioote surfoce ignition T

1

/.0. ,

+

%.8-3

/

<“Q.. i

.6

.4

(d]

,04 .05 .06 .07 .08 .09 - Jo .I1 ./2Fuel-oir roiio ●

(d) Variationof iudfcatcd specific liqnld ocmmmptlon and knock-lfmitml fniet-olr prwsu.re with furl-dr ratio at inh!t-air tcmpcraturc of IW F.

Fmt’RE &—Concluded.

‘--” ‘- “- ‘-”-- ‘------- ‘---– OF SEVERAL INTERh-AL COOWW’TS 101JiN UUJi-lJL3M 1 hlJ rlL4U UktlllAN Ch

Knock-1imited indicated mean effective pressure as afunction of indicated specific liquid consumption for theinterred coolants of figure 7 is plotted in figure 8. Waterraised the indicated mean effective pressure at considerableexpense to the indicated spectic liquid consumption. Forknock-limited indicated mean effective pressures aboreabout 240 pounds per square inch, methyI alcohoI - watertmclmonomethylamine+vater solutions were more economi-CU1from weight considerateions than fuel alone.

SUhIMARY OF RESULTS

From the resultsof an investigation of the effect of internaIcwcdingon the knock-limited performance of LX-F-28 fuel,the following results were obtained:

1. IfI all cases the use of methyl aIcohoI - water, mono-methylmnim+water, and dimethylamine+vater tit urea asinterred coolants raised the knocktited performance ofAN–F–28 fuel more than did water aIone.

2. The aclc[itionof ammonia to the methyl aIcohoI - watersolution as an internal cooIant lowered the knock-inhibitingeffpcts of the soIution and also promoted surface ignition.

:3. The commercial trimethylamine-w-atersolution Ioweredthe knock-limited performance of the KS–F–28 fueI exceptin the very McAmixture region.

1

480!

f

.-

+

9440 / _

4 /,

1 % -/ /

R&h rq icm 1400 .

e I fi/ ‘/ yLeon reqicm ~

..s

$360 ~I

) [

i ‘ Ig

fnf ernol caafonf

1d

(injected S /b//b fuel)tl* 320; I ❑ Water

~::20 70-30 percent pal) meihyt

a[cohol- waterT?i* il.

4 v 32-6a pffcd (w+)+

~ 280: ,

monomefhylomlne -wufer

ks+5 w 26-7+ percenf (wf)

< dim fhylamine-wa Fer

1❑

240 I11

> \f

, /

200/ /

(4 f

<

i6040 6i7 80 loo 120 MO f60

Mnao.k-limifed inlef-oir pressure, in. Hg abs

.FIG~EE7.—EtTrctoflntemral cmkants 1.2,4, and 6 on relatkm between kr.mek-usrritecfInfet-dh pre?snre and knOck-lfrrrIfed fndieated mean efleet Ire pmkss. CFR enginfi fneI,AN-F-& emup++sslon rstb, 7.N frdet-eoolsnt temperature, W F; irdet+fr tempemture,W F: spark advance, $& B. T. C.: engine speed, ~ rpm.

‘$+310T-5&S

FKXEE 8.– Effeet of Internal coolsnts 1, 2j 4, md 5 on relatbn kwtween Lrrdfmted SW[6C

Umdd mrrsumptbn and kmwk-Iimhd mm effeetlve ‘pressure. CFR enginq fuel, .LX-F-3 eompreasion ratio, 7.0. frrlet-cdant tempemture, 2ST F;W.4ak temwture, W

F; SLKWk ~dmme, W B. T. C.; engfrw spe@ 2s(s3rpm,

4. At fuel-air ratios of 0.05 or Ices, extremely high Iinock-Limitedporers could be obtained by using internal cookmts.

5. At fuel-ak ratios lower than the stoichiometric-rnixtureratio, addition of each of the interred coolants except watwlowered the indicated specific fuel consumption, in some casesto an amount greater than can be e.splained by comideringthe contributions of the internaI coolant to the heat of com-bustioti.

6. lhtermd cooIing at extremely low fueI-air ratios allowedhigh lcnock-Iimitecl powers at much Iowcr indicated specificliquid consumption than were obtained when operating at

high fuel-air ratios either with or without internal cooling.@can-mixture operation, of course, implies high indicatedspecific air consumption.)

7. The use of monomethyIamine-water mi~ture at aninlet-air temperature of 150° F and a fuel-air ratio of 0.049rd.lo-iveda knock-limited power of 1.96 horsepower per cubicinch of cylinder displacement (imep of 620 Ib/sq in.). Thecorresponding indicated specific fuel and liquid consumptionmere 0.37 and 0.55 pound per horsepower-hour, respectively.

&RCRAFT ENGINE RESEARCH LABORATORY-,

NATIONAL hWSORY COMMITTEE FOR AERONAUTICS,

C’LIXELAND, OHIO, February 1, 1944.