! . \ i NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS
TECHNICAL NOTE
No. 1374
EXPERIMENTAL STUDIES OF THE KNOCK - LIlvITTED BLENDIDG
CHARACTERISTICS OF AVIATION FUELS
II - INVESTIGATION OF LEADED PARAFFINIC FUELS
IN AN AIR-COOLED CYLrnDER
By Jerrold D. Wear and Newell D. Sanders
Flight Propulsion Research Laboratory Cleveland, Ohio
Washington July 1947 , \ I NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS
TN 1374 EXPERIMENTAL STUDIES OF THE KNOCK-LIMITED BLENDING
CH.~~ACTERISTICS OF AVIATION FUELS
II - INVESTIGATION OF LEADED PARAFFINIC FUELS
IN ~~ AIR-COOLED CYLINDER
By Jerrold D. Wear and. Newell D. Sanders
SUMMARY
The relation between knock limit and blend composition of selected aviation fuel components individually blended with virgin base and ''lith alkylate was determined in a full-scale air-cooled aircraft-·engine cylinder. In addition the follow ing correlations were examined:
(a) The knock-·limited performance of a full -scale engine at lean-mixture operation plotted against the knock-limited perform ance of the engine at rich-mixture operation for a series of fuels
(b) The knock-limited performance of a full-scale engine at rich-mixture operation plotted against the knock-limited perform ance at rich-mixture operation of a small-scale engine for a series of fuels
In each case the following methods of specifying the knock limi ted perfOl'IDanCe of the engine were investigated:
(l) Knock·-limited indicated mean effective pressure
(2) percentage of S-4 plus 4 ml T~~ per gallon in M-4 plus 4 ml TEL per gallon to give an equal knock-limited indicated mean effective pressure
(3) Ratio of indicated mean effective pressure of test fuel ~o indicated mean effective pressure of clear S-4 reference fuel, all other conditions being the same .
,. 2 NACA TN No. 1374
Results ind.:!.cated that the knock-limited indicated mean effec ti ve pressUJ.'es of the i)alC'uffinic fuels investigated, except the neohexane blends at l ean mixttrres for a srark advance of 200 B.T . C. , followed the reciprocal blending equation provided that the temper ature of the cylinder ,valls near the knocking zone was held con stant.
Percentage of 8-4 re:Cercnce fuel in M-4 reference fuel (both fuels containing 4 ml TEL/gal) for an equal knock-limited indicated mean e:'fective pressu.re of the -paraffinic fuels tested at a spark advance cf 200 B.T .C. gave ratin88 of the paraffinic fuels that were inde'p endent of the type of engine used in these tests and of the f uel-air ratio ,
INTRODUCTION
An investigation of the knnck-limited blending characteris tics of aviation-fuel cOTh~onents is being conducted at the NACA Cleveland laboratory to determine the ex~ent of the applicability ~t' the r eciprocal blenchng relation developed in reference 1. This relation is as foll0Y1S:
1 Nl N2 N3 imell =~ imell ) 1 + ( imsll ) 2 + "(Tmell) 3 +
where
imen knock-limited indicated mean eff.ecti ve pressure of the fuel blend
knock-limited indicated mean effective pressures of compo nents 1, 2, 3, .. 'J respec tively, when individually tested
mass fractions of comllonents 1,
2, 3 J • • • , r espectively, in the fuel blend
The results of a preliminary investigation (reference 2) with blends of a 62-·octane paraffinic gaSOline and an aviation alkylate and. blends of 8 al'1d M ref0rence fuels indicated that the NACA TN No . 1374 3 reciprocal blending relation derived in reference 1 is applicable to blends of para:ffinic fuels at rich mixtures. On the other hand, the relation was not applicable to lean-mixture data for parei' £'inic fuels and is probable that the disagreement may have resulted from improper control of cylinder temperatures adjacent to' the knocking zone.
The primary purpose of the investigation reported is to study the blending characteristics of a number of leaded paraf finic aviation-fuel comp~nentB in a full-Bcale air-cooled engine cylinder. A secondary purpose is to compare the following cor relations :
(a) The knock- limited performance of a full-scale engine at lean-mixture operation plotted against the knock-limited perform ance of the engine at rich-mixture operation for a series of fuels
(b) The knock- limited perfolnance of a full -scale engine at rich-mixture operation plotted against the knock-limite.d perform ance at rich-mixture operation of a small-scale engine for a series of fuels
In each case the ..following methods of specifying the knock-limited ~erformance of the engine were investigated;
(1) Knock-limited indicated mean effective pressure
(2) PercentaGe of 8 -4 plus 4 ml TEL per gallon in M-4 plus 4 ml TEL per gallon to give an equal knock-limited indicated mean effective pressure
(3) Ratio of indicated mean effective pressure of test fuel to indicated mean effective pressure of clear 8-4 reference fuel, all other conditions being the same
RUns were made on a full-scale air-cooled cylinder; F-4 rat ings were determined for most of the blends.
FUELS
The base fuels used in this investigation were alkylate and virgin base . The blending components VTere : 4 NACA TN No . 1374
Triptane (2,2)3-trimethylbutane) Rot -ac id octane Isopentane (2-methylDutane) Diis~pr opyl (2,3-dimethylbutane) Neohexane (2,2-dimethylbutane)
The base fuels and all blending components contained 4 ml TEL per gallon.
Triptane, hot -acid octane, isopentane, diisopropyl, and. neohexane were individually blended with a virgin base stock and tested at spark advances of 200 and 300 B.T.C . Triptane and hot acid octane were blended ,vith alkylate and tested at a spark advance of 200 B.T.C.
The following referen('.e fuels were also investigated at these engine coaditions to obtain the reference-fuel framework:
8 - 4 8 - 4 plus 4 ml TEL per gallon 50-percent 8-4 and 50-percent M-4 both leaded to 4 ml TEL per gallon
The triptane was supplied by the General Motors Corporation.
APPARATU8 AND PROCEDURE
An investigation was conducted with an R- 2800 cylinder mounted on a CUE crankcase. The apparatus was the same as described in detail in reference 2, with the addition of a thermo COU"91e embedded in the cylinc_er head about one-sixteenth inch f r om the combust-Lon-chamber vTall at the exhaust end zone (fig. 1) . The knocking zone was assumed to coincicle vTi th the exhaust end zone . _~ automatic temperature regulator was attached to this thermo couple and controlled the cooling-air flow to maintain the temper ature constant at the thermocou?le.
The engine vTaS operated at the following conditions, which were changed from the conditions in reference 2 to permit a greater percentage of tri-ptane in base fuel to be tested: NACA TN No . 1374 5
Compression ratio . . . . • • • • • 7. 7 Spark advance, deg B,T .C . . · 20 and 30 Engine speed, rpm . . • . 2000 Condition of fuel-air mixture Prevaporized Inlet-mixture temperature, of . • • . • 240 Cooling- air temperature, of ...... , , , . . 100 to 110 Cylinder-head tenperature at exhaust end zone, of • • , •• 350 The temperature of the rear spark-plug bushing varied f r om 3750 to 4250 F .
The test procedure was the same as the procedure described in reference 2.
RESUI,TS AND DISCUSSION
Mixture - res~onse curves. - The mixture-response curves for the reference fuels (8-4 and -~O-percent 8-4 plus 50-percent M-4), base fuels, and blends of base fuels and blending agents are shown in figure 2 . The blends of base fuels and blending agents shown contain the maximt~ concentration of blending agents tes ted in this investigation. Complete mixture-response curves were not obtained for blends of lower concentration.
The knock-limited performance of var ious blends of base fuels with blending components at fuel-air ratios of 0 . 067 and 0 . 10 is stumnarized in table I. The performance values are given in terms of knock- limited indicated mean effective pressure for t"ro spark settings .
The variation of knock- limited indicated mean effective pressure "7ith blend co:mposition of blends of 8- 4 plus 4 ml TEL per gallon with M··4 plus 4 ml TEL per gallon are given in figure 3 . Inter?olated mixture-response curves of blends of the same refer ence fuels for intervals of 5-percent concentration of S-4 are shown in figure 4 . The ordinate is a reciprocal scale and, because the data in figure 3 fallon straight lines, the curves are equally spaced. A curve of cl ear S-4 is also shown on this figure .
Relation of knock limit to blend composition . - The varia tion of knock- limited indicated mean effective pressure with blend composition of several fuels i s shovm in figures 5 to 11. 6 NACA TN No. 1374
The ordinate's are reciprocal scales of knock-limited indicated mean effective pressure and the abscissas are lir..ear scales of blend composition expressed as percentage by i"eight . Data are plotted from figure 2 and table I. With the exception of neohexane at lean mixtQTes for a spark advance o~ 200 B.T.C . (fig. ll(a)), the data can be repreaented by straight lines,
Triptane. - Triptane is of special interest because it gives the highest knock-limited performance of all the paraffinic fuels tested. The knock-limited-mixture··response curves for pure trip tane plus 4 ml TEL per gallon at both spark settings are extrapo lated from data for blends with virgin base (fig. 2) as shown in figlITe 12 . The curves are equally spaced on a reCiprocal ordinate scale because the data in figure 5 fallon straight lines . The performance of triptane is greatly depreciated by advancing the s:park.
Correlation of knock ratings. - The aSSigned ratings for the fuels studied at spark ad'~E)S-oL 200 and 300 B.T.C. and also the F -4 ratings are presented in table II. Ratings above 100 (expressed in terms of percentage S-4 with M-4) were estimated by means of the straight-line extrapolations in figure 3. Similar extrapolations were used to obtain F-4 ratings above 100.
The correlations of indicated mean effective pressure rich against indicated mean effective pressure lean (knock-limited imep obtained from the full,-scale air-cooled cylinder at fuel air ratios of 0 . 10 and 0.067, respectively) (fig. l3(a)) and of indicated mean effective pressure at F -4 conditions (knock limited imep obtained from an F4 engine at a fuel-air ratio of 0 . 11) against indicated moan effective pressure rich (fig. 14(a)) are good for a spark advance of 200 B.T.C . The data points for t.he various paraffins scatter, however, on either side of the correlation line at a spark advance of 300 B.T.C. for indicated mean effective pressure rich against indicated mean effective pressure lean (fig. l3(b)) . This line is established by the two reference fuels, 8-4 plus 4 ml TEL per gallon and the mixture of 50-percent 8-4 and 50-percent M-4 both leaded to 4 ml TEL per gallon. This result indicates that as the severity of engine conditions was increased, the constancy of engine ratings of one paraffin in tel~ of two other paraffins did not always hold. The indicated mean effective pressure at F-4 conditions against indicated mean effective pressure rich also shows more deviation from the correlation line as engine conditions i.;ere increased in severity (fig. l4(b)) .
------~ NACA TN No. 1374
Ratings expressed as percentage S-4 in M-4 (both fuels con taininG 4 ml TEJJ/gal) for eQual knock-limited indicated mean effective pressnre of the paraffinlc fuels at a spark advance 0 of 20 B.T. C. ShOVT good correlation when full-scale engine lean mixtu~e ~erformaDce is plotted against full-scale engine rich mixturo operation (fig . 15). The correlation is a]so good when :1:' ull-scale engine rich·mixture operation at 200 B.T.C. is 1) lotted against the F-4 condition (flg. 16) .
Ratings expressed as ratios of block-limited indicated mean effective pressure of test fuel relative to indicated mean effective pressure of clear 8-4 at eithGr spark setting are Lot as constant for rich against lean-mixture operation (fig.17) as they are for F-4 condition against rich-mixture operation (fig. 18) >
SUMMARY OF RESUL'I'S
From an investigat ion of aviation fuel components indi vidually blended wit::-t virgin base and alkylate to determine the relation between h~ock limit and blend composition and to com pare methods of correlating the knock .. limited data) the following i'csults ,,-ere obtained :
1" The knock-limited indicated mean effective pressure of the uo.rn.ffinic fuels tested (vlith the exception of neohexane at lean- r:.ixtures for a spark advance of 20 0 B.T .C.) followed the recivr ocal blending eQuation provided that the temperature of the cylinder walls near the knocking zone was held constant.
2. Knock-limited performance expressed in terms of percent age 8 -4 in M-4 (both fuels contain 4 ml TEL/gal) to give an equal lnlock- limited indicated mean effective pressure gave ratings of the paraffinic fuels tested that correlated better than ratings expressed by knock-limited indicated ~ean effective pressure or rutio of indicated TIean effective press~e of test fuel to the indicated mean e:fective pressure of clear S-4 reference fuel. Correlation of ratings specified by ratio of indicated mean e:C'fectj.ve uressure of test fuel to indicated mean effective pres sure of clear 8-4 referonce fuel was not as good as the other two methods . 8 NACA TN No . 1374
3 . Percent age of S-4 reference fuel in M-4 reference fuel (both fuels containing 4 ml TEL/Bal) f or an equal knock-limited indicated mean eff ective pressure of the paraffinic fuels tested at a spark advance of 200 B.T.C. gave ratings of the paraffinic fuels that were independent of the type of engine used in these runs and' of the fuel-air ratio. However, the ratings were not independent of the type of engine and the fuel-air ratio when the spal'k setting was increased from 200 to 300 B. T. C.
Flight Propulsion Research Laboratory, National Advisory Committee for Aeronautics, Cleveland, Ohio , June 4, 1947 .
REFERENCES
1. Sanders, Newell D. : A Method of Estimating the Knock Rating of Hydrocarbon Fuel Blends. NACA Rep . No. 760, 1943.
2. Sanders, Newell D. , Hensley, Reece V., and Breitwieser, Roland: Experimental Studies of the Knock-Limited Blending Character istics of Aviation Fuels . I - Preliminary Tests in an Air Cooled Cy1i.nder. NACA ARR No . E4128, 1944. N ACA TN No. 1374 9
TABLE I - KNOCK-LIMITED INDICATED MEAN EFFECTIVE PRESSURE OF BLENDS OP AVIATION FUEL COMPONENTS WITH BASE FUELS ~11-scale air-cooled cylinder; c~ression ratio, 7.7; engine speed, 2000 rpm; inlet mixture temperature, 2400 Fi cy1Inder~ead te~erature at exhaust end zone, 3500 F. All fuels contained 4 ml TEL/ga~
Spark advance. 200 B.T.C. SJlat-JC_ advance___ ~Qo_ B.T.e. Fuel blena lme2 Fuel. bl.end l.JI1ep (percent by weight) t:\ieI-aIr ratIo (percent by weight Fuel-air ratIo 0.067 0._1_0 0.067 0.10 5-4 M-4 5,-_4_ )0(-4 61.7 38.3 108 139 62.6 37.4 100 136 72.3 27.7 135 156 75.0 25.0 119 155 82.4 17.6 168 185 84.8 16.2 144 174 90.0 10.0 196 214 92.5 7.5 169 204 95.0 5.0 21B 23B ------Triptane Virgin Triptane [VIrgin ------base base 10.1 1j9.9 159 182 l.:>.l. 84,.9 128 175 20.0 80.0 177 200 30.1 69'.9 140 201 30.2 69.8 199 216 40.2 59.8 169 225 39.8 60.2 221 241 50.0 50.0 182 256 ------. ------60.1 39.9 206 ------Hot-acid Virgin Hot-acId lJ'irgin octane base octane base 10.0 90.0 155 172 14.9 85.1 124 170 25.5 74.5 171 189 30.0 70.0 134 186 39.9 60.1 185 203 49.8 50.2 150 212 55.2 44.8 207 231 66.0 35.0 172 237 70.0 30.0 224 256 ------80.3 19.7 246 280 ------90.2 9.8 261 311 ------Isopentane Virgin ,Isopentane VIrgin i . base base 1.0.1. 89.9 157 167 1.:>.0 1j5.0 122 166 19.8 80.2 161 175 32.2 67.8 136 173 34.8 65.2 173 182 50.0 50.0 146 ------42.4 57.6 179 188 ------Dl1sopropy Virgin DIlsopropy [V1rgin ------base base 21..9 78.1. 173 186 1.9.9 80.1. 131 174 35.1 64.9 197 214 38.8 61.2 150 199 54.8 45.2 221 245 55.2 44.6 166 222 70.0 30.0 253 279 68.8 31.2 179 246 Neohexane Virgin Neohexane IVirgin base base 13.5 86.5 161 176 20.3 79.7 131 171 30.1 69.9 174 189 38.5 61.5 145 188 45.1 54.9 18B 200 53.0 47.0 167 203 64.7 35.3 206 214 60.0 40.0 ------20B 83.B 16.2 225 233 ------Triptane :Al.kY1ate NATIONAL ADVISORY 7.7 92.3 212 241 COMMITTEE FOR AERONAUTICS 15.1 84.9 225 256 25.1 74.9 244 272 33.3 66.7 260 297 40.0 60.0 ------30B Hot-ac1d [Al.Ky~ate octane 1.0.1. 210 236 24.9 ;~:~ 224 251 45.0 55.0 235 266 64.8 35.2 249 291 85.0 15.0 264 321 10 NACA TN No. 1374
TABLE II - COMPARISON OF KNOCK LIMITS OF 10 FUELS IN FULL-SCALE AIR-COOL!D CYLINDER AND F-4 ENGINE [For eaoh oompound there are three rows of values: the first row is imep, Ib/sq tn.a the second is percentage 5-4 + 4 ml TEL/gal 1n M-4 + 4 ml TEL/gala and the third row is the ratio ot imep ot test tuel to imep of olear 8-4. Compression ratio, 7.7; spark advanee, 200 and 300 B.T.C.; o engine speed, 2000 rpma inlet ~1xture temperature, 2400 F; cylinder-head temperature at exhaust end zone, 3500 FJ
NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS Fuel Conoen- F-4 FUll-scale au--cooled cyllilCler tration engine SpI!rk advance, -Spark aavance, ot TEL (tuel- 20° B.T.C. 300 B.T.C. (ml/gal) air ~el-alr ratio r'uel-aTr ratlO ratio, 0.067 0.10 ~O.lJ67 1r.~-cr 0.11 ) Triptane 4 il740 il850 a700 a540 a760 (2,2,~trimethyl- 123 125 124 123 131 butane) 4.84 5.55 3.68 5.94 4.63 DllsopropyI 4 3Zt) "'360 1&3Bt> ~~7 01:300 (2,3-dlmethyl- 109.5 111.5 112 108 112 butane) 2.12 2.35 2.02 2.71 2.11 Hot-ac id oc tane 4 a310 281 345 a218 a328 108 105 109 104 112 2.03 1.84 1.82 2.40 2.14 5-4 reterenoe 4 233 244 268 198 239 tuel 100 100 100 100 100 1.52 1.60 1.41 2.20 1.56 Neohexane 4 a243 233 2lS6 il270 a264 (2,2-dlmeth'11- 102 98 98 109 105 butane) 1.59 1.52 1.35 2.86 1.72 Isopentane 4 a210 8243 8240 az16 8220 (2-meth'11butane) 96 99.5 95 103 97 1.37 1.59 1.26 2.37 1.44 Alkylate 4 196 202 232 ------93.5 93.5 93.5 -- - 1.28 1.32 1.22 ------Virgin base stock 4 139 147 165 114 153 77.5 76.5 76 72 74 0.91 0.96 0.87 1.25 1.00 a SO-perc ent s-4 4 93 101 118 87 114 + 50-percent M-4 SO 50 50 50 50 0.61 0.66 0.62 0.955 0.745 s-4 reference 0 153 153 190 91 163 tuel 82.5 79 83.5 63 74 1.00 1.00 1.00 1.00 1.00 ilExtrapo1ated trom data tor blends. NACA TN NO. 1374 Fi g.
I •
NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS
A I n t ak e val ve F Thermocouple to measure B Rear spark plug temperature of combust ion C Exhaust va Ive chamber wal I at exhaust o Front spark plug end zone E Exhaust end zone G Piston
Figure I. Approximate location of exhaust end zone.
NACA TN No. 1374 Fig. 2
ruel • ./ ~ ~ ~-percent 8-4 • 50-percent H-4 lrgln ba .. / 50-percent l.op.ntane + 5O-p.r- ~ c.nt "lrgln ba.& x Alkll&te f ~ N.ohuan. + 5O-p.roent ,,1rgln ba.e + 5O-per- cent trlptan& 0 8-4 rat.r.no. tu.l
.~ .06 .011 .10 .12 .04 .06 .08 .10 .12. hal-ail' 1'8 tio 0 0 (.) Spark advaDoe, 20 B.T.C. (b) Spark advance, 30 B.r.c,
J'1&w'e 2. - Xnoclc-l1mUed performance of aviat1oZlo-fual components, base fuels, reference fuels, and blend a of aviation-Iud components and bue fuels. Full-scale air-cool8d cylinder; CO~ pression ratio, 7.7; ell8ine speed, 2000 rpm; inlet mixture temperature. 240 1; c)"l1nci.er-head 0 ""'perature at exhaust end lOne, 350 r. Fi g. 3 N ACA TN NO. 1374
1000 800 NATIONAL ADVISORY 00 COMMITTEE FOR AERONAUTICS I00 J I 500 450 / I l I 400 ,, ,50 .1 /, ~ I, ,00 /1 28 0 I ' ( 2 60 ~' 0 /[~ " " ,.' / 0 ?/ ~ I j? !eI I 2 00 J 1 90 /1 ~~ 180 1>-'1 L 1 j 170 ) I 7 1 60 / 19 ~
1 50 lP rf 1 Fuel-all V ratio 0 / / ) !i 0.10 lP l.6 8 .067 V 1 ,0 I~
12 0 / / / uL 11 II C~ 1 10 J 0
1"" V 60 100 120 60 100 120 S~ 1n ~1.a4. percent ~1 wel8ht
(a) Spark advance, 20° B.T.O. (b) Spark adYance, 30° B.T.O. figure 3. - Relation of knock 11mit to composition of blends of S-~ with M-~. All fuels oontaln 4 ml TEL per gallon. Full-Icale air-cooled cyllnder; compre ssion ratl0, 7.7; englne speed, 2000 rpm; inlet mixture temperature, 2400 Fj oyli nder- head temperature at exhault end ~one, 3500 r. NACA TN No. 1374 FI g. 4
0 I Percentage 5-4 • 1+ III 1'~al T ..... "100 w1th M-I+ • 1+ ml TEL/g I Or--- .- ~ - _,....0 100 0 " , .., -.., .. ' A" 0 ... . 90 . - " ...... ' .. , .. ~ _.. - .--- 200 ~ .. 90 e, ' . 0 .. -... J- /' .' ." 19 _...... - , .Y ' gO , .- .. I 18 0 .- 0 ...... e .. , .. g. , "c) , , 80 " ...--- .. I .. " JJ. 17 0 " .... , , , -' , 70 \ , ']oJ I;" ..1:1' . .' I .. ' 16 0 , , CD ..... ' , , I ~, r-4 1{•. , .. , , .....j ~-? ..... '.' I 3 15 0 , ,. " , , ", , 70 ~ III \"1 .. ,60 , , , . ,. .. ' , .. .. ' , .. , • , , " 0 . .' .. .. ~' J: .. .. - .. , , I , . \ .. . .. '.' , , , I • , .. ' , ' , , , , .. " " I .. .. , , , , , .. .. -"'60 0 .. . , .. . .. , ... ..- \ • .' 0 , , ...... - \ , , , , .. . '. , , .. rt'5 ..... , , , , . . .- ·,, , ,.' ..;; , , , .. ,. - 12 0 . . , , "1 . ,, , . .... , , , .' . --0- 50 c:2 , , , , , , , I . k[ p , .. , I . .. , ,l ," 7 , ''''III , .. - , ,, ~" ,...... 0 110 .' .. Y , ,, , , " ••, , ' , , , ~ '.- / ' / p'" \ ' ' , , I "~ \ 100 , , I t , I , ./ ~, I, b. ,, , , ~ 95 l'I1el 50-percent S_I+ + ~ 0 0 50- /~ 9 percent M-I+ + 1+ ml TEL/gal 0 S-I+ + 1+ ml TB:L/gal •• ,',- CJ S-I+ 1 , 85 r \ , t~ 8 0 Il .. ,~ 75 !l.I"'" NATIONAL AOV I StRy COMM I TTEE FOR AERONAUTICS
7 .06 .OS .10 .12 .04 .06 .OS .10 .12 F\lel-a1r rat10 (a) Spark advance, 200 1.1'.0. (b) Spark advance, ,00 B.T.C. Plcure ~. - Blen~lng charaoter1.ticl ot &-4 and M-I+ retereno. fu.l. plus 4 .1 TEL per gallon. Full-scale air-cooled cylinder; oompr,ss1on ratio. 7.7; engine speed, 2000 rpm; inlet m1xture temperature, 240G F: C111nder-head temperature at exhaust end %one, 3500 r. Fi g. 5 N ACA TN No. 1374
1000 800 NATIONAL ADVISORY 700 COMMITTEE FOR AERONAUTICS // / 600 l{/ 500 ~ 450 , Y , / / 400 / .... ,,/ V '50 "" . r-4• ;/ 3 / /1 II ,00 /" I / / r-4 280 (P' ." / 3 260 f I At oLP /' 004 z40 0 220 / '/ 6 [/ ...... " Fuel-a1.r . zoo ~/ rat1.o cI p !i 190 Z 7 0 0.10 / r:I' 0 .067 .. 180 0 / If ~ r-4 / P 6 / . 170 , At 160 / ~ • ) !i 150 / I ~• J .. 140 £ ..a r-4 I 1,0 / ~ ~ ! lZ0
110 / .J
100 o 25 75 100 o 25 50 75 100
Tr1.ptane in blend, peroent by we1ght 0 (a) Spark advance, 20 B.T.C. (b) Spark advanoe, 300 B.T.C. F1gure 5. - Relation of knock lim1.t to compos1tion of blends of tr1ptane with v1rg1n base conta1ning 4 ml TEL per gallon. Full-leale air-cooled cyl1nder; compre661.on ratio,. 7.7; engine speed, 2000 rpm; inlet mixture temperature, 2400 F; cyl1.nder head temperature at exhaust end zone, 350° F.
-- -~ NACA TN No . 1374 Fi g. 6
1000 800 NATIONAL ADVISORY . 700 COMMITTEE FOR AERONAUTICS .' 600 ~ " ...... ". 500 , 45 0 400 ".1 ,," ~ ..... 0 '5 ,/ b'''c: .... ,00 ~ .>-' ,/ 28 0 0 VU rr 26 Fuel-air D V d ratio 24 01>' J:t:: 0 0.10 22 0 0 .067 2 00 A . t" S 1 90 180 1/1 ...... • 170 ~ . 1 60 J 1 50 ..~ 0 ~ 1 ,0 ~ ! 12 0
I 1 1
1 "" o 100 rlgure 6. - Relat10n of knock l1mIt to composIt1on of blend. of trlptane with alkylate containIng 4 ml TEL per gallon. Full-scale aIr-cooled cylInder; compressIon ratIo, 7.7; engIne speed, 2000 rpmi Anlet m1xture temperature, 2400 ri cylInder-head tempera ture at exhaust end zone, 350 'i spark adYance, 200 B.T.C. F ig. 7 NACA TN No. 1:374
1000 800 NATIONAL ADVISORY 700 COMMITTEE FOR AERONAUTICS 600 500 450 400 Fuel-air '50 rat10 '" • V 0 0.10 "," ,00 0 .067 i 280 -./ h • ,;-' l,./ :p' ~ 260 3 V rV ~ / 240 p ~ r( /" ! 220 £ k{' /1 /' .... 200 D"'" a• 190 ./ ./ ./ ~ / lO' l,.O L 0' 180 'W :&r• 170 ~ V V In/ " 160 ~ /'" /' 7' /- (If / j 150 JJ 1.. 140 / ! 1,0 ~ "I ~ ~ ! 120 (( 110
100 o 25 75 100 o 25 75 100 Hot-aold ootane 1n blend, pero.nt by we1ght 0 1000 800 NATIONAL ADVISORY 700 COMMITTEE FOR AERONAUTICS 600 f - 500 45 0 400 }5 0 ~ ~oo ~ bQ:: 28 0 ...... - r-- 26 0 .....cr' .I"I-- I-' r- ~ _ .-fr" 24 o~ 0 f-U"" 220 I-- Ir---"' 200 b--1 19 0 18 0 Fuel-air 17 0 ratio 16 0 0 0.10 0 .067 150 0 1}0 120 110 100 o 20 60 so 100 Hot-acid ootane in blend, percent by weight Figure 8. - Relation ot knock limit to composition ot blends ot hot-aoid octane with alkllate containing 4 al TiL per gallon. Full-scale air-cooled cylinder; compression ratlo, 7.7; engine speed, 2000 rpm; Anlet mixture temperatgre, 2400 P; cylinder-head temperature at exhaust end zone, 350 F; spark advance, 20 B.T.C. Fi g. 9 N AC A TN No. 1374 1000 800 NATIONAL ADVISORY 700 COMMITTEE FOR AERONAUTICS 600 500 450 400 ...... '50 III r"4 aI ,00 0 • 280 r"4 3 260 e 240 ...t:Io ~/ ., 220 , J.• - .-- / 200 --" -- ~ .' ... c::. 190 ...J. -" ~ ... - / ~ "Vi II- J. ~ 0' 1.80 .;r ... / ...... -~ n LP-- J:l 170 1J7-" r"4 n,.. V po- // 160 .-' t:Io q,. V // •a 150 .P I ... po Fuel-a1r rat 10 ) ""• 140 ..... 0 0.10 1/ ...Ei 0 .067 r"4 1,0 9" .J f' 0 0a ;oC 120 V Iy 110 100 o 75 100 o 75 100 lsopentane in blend, percent by we1ght (a) Spark adyance. 20° B.T.C. (b) Spark ad.ance. 300 B.f.C. figure 9. - Relat10n ot knock 11m1t to compos1tion ot blends ot 1sopentane w1th y1rg1n base conta1n1ng ~ ml TEL per gallon. Full-scale a1r-cooled cyl1nder; compress10n rat10. 7.7; eng1ne speed, 2000 rpm; inlet m1xture temperature. 2400 F; cylinder-head temperature at exhaust end zone, 3500 r. N ACA TN NO. 1374 Fi g. 10 1000 800 NATIONAL ADVISORY 700 COMMITTEE FOR AERONAUTICS 600 ~ -.D to- 500 450 400 / '50 [" - ~ , ,00 J' 1/' .- II .~~ ... 280 V u.. /' IIU D/ ...• 260 240 9/ JY 0/ ~ :I V , £ / Q../' , A. 220 '"1"ll"" ..4 / / 0 V II ) ./ 0/ IT' So 200 190 Vl: L V c:. 180 /" / /" r< ..4 / / rY "• 170 P' ;:r ..... V Jf ~... 160 / V h/ A. 150 II Fuel-all' V P" rat 10 !I 140 / ., 0.10 .. .oli7 V ..4.. 1,0 8 0' .....4• V .J u 120 / 0 :J P" 110 100 o 25 75 100 o 25 75 100 D11soproP11 1n blend, percent b1 we1ght 0 (a) Spark adyance, 20 B.t.C. (b) Spark ad.ance, )00 B.T.cG F1gure 10. - Relat10n of knock l~1t to compos1t10n of blends of 411sopropyl v1~ v1rgin base conta1nlng 4 ml tEL per gallon. Full-scale a1r-cooled c1l1nder; compress10n rat10, 7.7; eng1ne speed, 2000 rpm; inlet mixture temperature, 240° F; cyl1nder-head temperature at .. .maust end zone, ~500 F. Fi g. I I N ACA TN No. I 374 1000 800 NATIONAL ADVISORY 700 COMMITTEE FOR AERONAUTICS 600 500 450 400 '50 ,00 280 260 .-/IJ 240 "':: ~II 10- ..... 220 ./ ~ 0' I V /' 200 r.. V ~ . .~ a. V V / 004 190 0" ~ ;n J. r¥ 180 / til ,., V' 170 ./ ~ ./ n/ ~ v /' ./ / 160 < 150 / / Fuel-air p f ratio 140 / 0 0.10 0 .067 []I V / / 120 IV 110 100 o 75 100 o 50 75 100 .eobexane in blend, percent by weight (a) Spark advance, 2CP B.t.C. (b) Spark advance, JCP B.T.C. Figure 11. - Relat10n or knock 11m1t to compos1t1on or blends or neohexane with virgin base containing 4 ml T~ per gallon. Full-scale air-cooled cylinder; 0 compress10n ratio, 7.7; engine speed, 2000 rpm; inlet m1xture temperature, 240 f; cylinder-bead temperature at exhaust end zone, 3SOO f. NACA iN No. 1374 Fi g. 12 NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS .I I 1000 , , U'\ SOO ---- ... I . -.0 700 .... _- .. --.. - C'-- 600 ~ I .. , 500 \ : .-' , , 450 ,-- 400 350 300 2S0 .A- ...... 260 ~ 240 / ./ .. f: [7 .... 220 ..:! ..",. .... 200 V 75 70 .04 .06 .os .10 .12 .04 .06 .10 .12 l'uel-air ratio (a) Spark advance, 200 B.T.C. (b) Spark advance, 300 B.T.C. Figure 12. - Extrapolated knock-limited ~ixture-response curve for triptane plus 4 ml TEL per gallon. l'ull-scale ail'-cooled cylinder; compression ratio, 7.7; engine speed, 2000 rpm; iDle t 0 0 mixture temperature, 240 F; cylinder-head temperature at exhaulit end zone I 350 r. L --_.------Fi g. 13a N ACA TN No. 1374. NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS [7 n 0 17 I , I 0 / I - 1.1 c:· ... I)' cr ~ 200 l/v ~ '/ / r-· 1/ '-Do • 0 V o 15 19 ~o '/ S V ~ cd r.. V ...r.. ill / I Fuel .-4 10 r< ~ ~ Triptane ~ V .., a Dl1sopropyl CIS / 6 Hot-acid octane 9 0 S-4 ~ V Neohexane •Ii: ~ ..4 D Isopentane x ~ 8I" / Alkylate ..,It V <> Virgin base ..4 0 50-percent s-4+50-percent M-4 ...Iii .-4 All fuels contain 4.0 ml TEL/gal I ~ 17r / ! V 80 90 100 150 200 ,00 500 1000 w Knock-limited lmep at fuel-alr ratio of 0.10, lb/sq In. (reciprocal scale) ta) Indicated mean etfective pressures at spark advanoe ot 200 B.T.C. Figure 13. - Correlation between knock llmits at rlch and lean mixtures. FUll-scale alr-cooled cylinder; compression ratio, 7.7; engine speed, 2000 rpm; inlet mixture temlterature. 21100 F; cylinder-head temperature at exhaust end zone. 350° F. NACA TN NO . 1374 Fi g. 13b NATIONAL AOVISORY COMMITTEE FOR AERONAUTICS 1000 50 0 1/ II 0 1/ • 1/ a ....c I~ 0 V ~ I 1/ 0 o j J II10 10 V V Fuel ~ Triptane 9 Q Dl1sopropyl 6 Hot-acld ootane "lP o s-ij. r I ~ Neohexane 8 8 Isopentane V Virgin base o 50-percent s-ij.+50-per cent M-ij. / All tuels oontaln ij..0 ml TEL/gal 7 80 100 200 500 1000 co Knook-11m1ted lmep at fuel-air ratio or 0.10, lb/sq 1D • . (reo1procal scale) (b) Indlcated mean ettective pressures at spark advanoe ot 300 B.T.O. Figure 13. - Concluded. Correlat10n between knock l1m1ts at r1ch and lean mixtures. FUll-scale air-cooled oy11nder. compression ratio, 7.7. engine speed, 2000 rpm: inlet miXture temperature, 2400 F: cylinder-head tempera ture at exhaust end zone, 350° r. Fi g. 14a NACA TN No. 1374 NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS V 100 a .. 50 a / ~ ~ o. \4 JJ ~ o a o .... ~ 1/ ~ ~ ,.. ~., 20a ~ ....al4I> - I~ ~aI 1/ 41>0 :SCI) II \4 ~ V ~cS 15 a 1110 A / G>f "7 ...... c::o. b/l0 / C::4I> 41>,.. V .=t I • J r..c::.... / c:: .... C' co 10 / 0., Fuel 4I>,Q ....a~ ~ Tr1ptane 9 ft a Dl1sopropyl 6 Hot-aold octane o 5-4- ~ Neohexane 1"1 I Isopentane 8 o )C Alkylate <> V1rgln base / o 5O-peroent 5-4+50-percent M-4. / All fuels contaln 4..0 ml TEL al 7 / 80 90 100 150 200 ,00 500 1000 ~ Knock-11mlted 1mep ln full-soale alr~oooled oyllnder at fuel-alr ratl0 or 0.10. lb/sq In. (reclprooal scale) (a) Ind1cated mean erfeotlve pressures at spark advance ot 200 B.T.C. F1gure 14.. _ Correlat1on between knook-limited data obta1ned at F-4 condl t10n& and ln full-scale a1r-cooled cylinder at the rollow1ng oond1tlons: Oompress10n rat10, 7.7; eng1ne speed, 2000 rpm; 1nlet m~ture temperature, 2400 r; cy11nder-bead temperature at exhaust end zone, 3500 r. N ACA TN NO. I 374 F i g. 14b NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS C• 100... .-4 0- CI) / 500 ~ rf I.l'\ / rf· /~ '"t'- rf In .. 0 • ~ /' 0 0 ,f .-4 200 .. I III So I/' .-4G/.. - / III'" I III A 15 V "'(1 ~ G! 10 / c Fuel .-4 Q, 9 I I!:.. Trlptane 80 90 100 150 200 ,00 500 1000 00 Knock-limited imep in rgll-seale air-cooled c7l1nder at tuel-alr ratl0 of O.lO,lb/sq In. (reeiprocal scale) (b) Ind1cated mean effect1ve pressures at spark advance ot ,ao B.T.C. Flgure l~. - Conclw1ed. CorrelaUon between knoek-l1mltec1 data obtained at r-~ condltlons and 1n full-seale a1r-cooled cy11nder at the tollow ing cond1tlons; Compress10n ratl0, 7.7; englne speed, 2000 rpm: 1nlet mixture tgmperature. 24ei> F: c11Wer-head temperat\ll'e at exhaust end zone, 350 F. Fi g. 15 N ACA TN NO. 137 4 . TT . NATIONAL ADVISORY COMMIT TEE FOR AERONAUTICS · · · Spark advance ruel (deg B.T.C.) · 20 30 ~ tI.... Trlptane a a... l)11soproPl1 160 Ll. A- Hot-acld octane ~ ~ Neobexane Match · D a. Isopentane 11ne ..... x Alkylate \D 0 ~ Vlrgin base 0 • l/ 0 140 All fuels contain 4 III 'l'EL/gal ~ / 0 / · 0 ...~ t/ GIl ~ J. 120 /" J. ~ III d'/ I .-4 d- It · :s _/~ ~ IZ '/ ~ · ... 100 v~ III tG J'/ · s: ...~ cd // · J. · .IIC 80 0 , c0 ~l/ a.: // 60 / / , /.1 :, I-,( ...... ' 60 so 100 120 1110 160 Knock ratlng at fuel-alr ratio of 0.10 Figure 15. - Correlation of knock-l1mited ratings at riob and lean mixtures expressed as peroentage or S-4 plus 4 ml TEL per gallon witb H-4 plus 4 ml TiL per gallon. FUll-scale air-cooled cl1inderi compression ratio, 7.7; engine speed, 2000 rpm; inlet mixture temperature, 2400 r; o7linder-bead temperature at exhaust end zone, 35()0 r. NACA TN NO. 1374 F i g. 16 l- . " NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS · · ,: Spark advance Fuel · (deg B.T.C.) · 20 30 ~ ~ Tr1ptane · 0 a.. D1isopropyl 6- 6.- Hot-ao1d octane ~ ~ Neohexane D Q Isopentane )( Alkylate · 0 ~ V1rg1n base All fuels oontain Match 4- ml TEL/gal line 140 · lL/ : J.4 .-4 «I ~ I 120 ~ r-4 :sQI f.,. IL/ , ~ ftS ~ · Qlr-4 ~ · t:r-4 100 ~ .-4 • s::bOO ~6 · G.lf.,. / · ;j-0 I 0 · fa..-4 // : ~ S::ftS 80 · .-4J.4 III :, ~ /~ s:: / .-4 • ~ // : f 60 .IIC () / 0 t: / · W : // · 40 ~ ..l. 40 60 80 100 120 140 Knook ratings in full-scale air-cooled cylinder at fuel-air ratio of 0.10 Figure 16. - Correlation of knock-limited ratings expressed as peroentage S-~ plus ~ ml TEL per gallon with M-4 plus 4 ml TEL per gallon. Data obtained at F-4 oonditions and in full-scale air-cooled oylinder at following oonditions: Compression ratio, 7.7; engine speed, 2000 rpm; inlet mixture temperature, 2400 F; oy11nder-head temperature at exhaust end zone, 3500 F. F i g. 17 NACA TN NO. 1374 • T T -.- -.- • • I .. • .: Spark advance Fuel NATIONAL ADVISORY (deg B.T.C.) COMMITTEE FOR AERONAUTICS 20 30 · ~ ~ Tr1ptane : a a.. Dl1sopropyl t::. t::... Hot-ac1d octane · 0 a.. 5-4- · o ~ 'L Neohexane 0 D.. Isopentane )( Alkylate 0 ... ------