INVESTIGATION
OF IET F U E L L U B R I C I T Y IN SERVICE
UDC
V. A. P i s k u n o v , V. G. G o r o d e t s k i i , E. I . D o m k i n , E. P. Seregin, and G. B. S k o v o r o d i n
665.521.3
In aviation gas-turbine engines, plunger-type fuel pumps are widely used; these are lubricated with the medium being pumped, in this case, the fuel. A characteristic design feature of theroeker unit of these pumps is the presence of plungers operating in a pair with the wobble plate of the thrust collar, with high contact stresses (up to 200 kgf/mmZ) and high relative displacement rates (up to 0.7 m/sec). These conditions produce rapid and severe wear of the plunger spheres, in some cases exceeding the allowable limit (0.6-0.8 ram) [1]. When a plunger sphere becomes worn to a certain degree, the contact point of the sphere with the wobble plate is shifted to the edge of the plunger, and this leads to a concentration of stress and chipping of the edge of the pIunger. The breakdown products, when they get into the eleararices of plunger or slide-valve pairs, will jam the parts and thus cause engine failures. This may be the reason for the phenomena observed at various stages in ~ae life of the engine, such as spontaneous stopping and refusal to start, spontaneous increase in engine speed, etc. It was shown in [1, 2] that, among the factors affecting the wear of the plunger spheres in fuel pumps, one of the most important is the lubricity of the jet fuel. In studying this factor, we carried out an investigation and correlation of the results from observations on large-scale service of regular-production gas-turbine engines on T-1 and TS-1 fuels produced by various refineries. The data obtained in this study are summarized in Tables 1 and 2 and further illustrated in Figs. 1 and 2. TABLE 1. Certain Physicochemieat Properties of Test Fuels
Fuel
DeNsity, g/era s
1 T-I (Baku refinery) 0,803--0,809 ~' 2 T-l(Krasuodar refinery) 3 T:.I(Komsomol rennevy) 0,821-0,826 4 TS-1 (Krasnovodsk refinery) 0,779--0,796 5 TS-I (Groznyi rennery) o,7ar 6 TS-1 ( Ryazan' refinery i 0,777--0,780 7 TS-I (Novo-Gor'kii rennery) 0,780---0,785 8 TS-1 (Novo-Ufa refinery) l 0,776---0,780 9 TS-I (Novo-Yaroslavl' 0,777--0,790 refinery)
o.sol-o,8171
. . . . . . Distilla-[ K memanc
tlon
Existent i [Ac~dlty.mg[gum eon~ [viscosity [KOH/I00 [tent,
total
mercaptan
range, ] at 20~
ml fuel
132--275 I 1,54--1,78
0,35--0,69
I35--267 I 1,1I--1,84
0,16--0,66
145--255[ 1,56-- 1,66
0,47--0,70
135--24t[ 1,30--6,53
0,25----0,56
136--2391 i~8---1,32 135--2201 1,26--1,3
0,30--0,44 0,09--0,28
135--230 t 1,27--1,30
0,23--0,27
9-,5--.3,2[0,031--0,53 0,0008--0,001 ,00--2,81 0,007--0,011 0,000--0,0006 1,8---3,010,130--0,I8 0,0013--0,0057 t,0--2,0t 0,li0--0,20_ 0,0024--0,0034
1~6--t,a2
0,12--0,49
1,2--1,61
135--2241 1,25--I ,38
0,11--0,29
o,v--2,51 o,mo-o,2o
137--223]
[ m~/100
Sulfur content, %
0,001--0,15 0,0015--0,0035 0,0017--0,0038
Translated from Khimiya i Tekhnotogiya Topliv i Masel, No. 3, pp. t4-16, March, 1976. 9 1976 Plenum Publishing Corporation, 227 West 17th Street, New York, N. Y. 1001L No part o f this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, microfilming, recording or otherwise, without written permission o f the publisher. A copy o f this article is available from the publisher
for $15.00.
184
TABLE 2. Results from Lubricity Tests on T-1 and TS-2 Fuels in Service
No
Fuel
Pump type
Pump -running time, h
$
~s
Average Qualification adjusted test rating Wear o f wear plunger (250-h)c VNII spheres,turf plunger NP KIIGA spheres,
s T - 1 ( Baku refine~} T-1 (~asnodar refiner@
NR-14(St.Khl2M) NR-22(St.Kh12M) NR-21(St.Khl2M) NR-14(St.Khl2M) T-1 (Komsomol refinery) NR-22(St.Kh12M) NR-21(St.Khl2M) TS - 1 ( Krasnovodsk re fine ry) NR-14(SZ.KhVG) NR-t4(StaKhl2M) TS-1 (Groznyi refinery) NR-14(St.KhVG) NR-t4(St.Khl2M) TS-1 (Ryazan' refinery) NR-22(St.Kh12M) NR-54(St.Kh12M) NR-1 St.KhVG) NR-I~St.Khl2M) TS - 1 ~ - ~ _ or'kii refinery) .......... NR-22(St.Kh12M) NR-21fSt.Khl2M) NR,-14(St.KhVG) TS-1 (N ovo-Ufa refinery) TS-1 (Novo-Yaroslavt' NR-14(St.KhVG) refinery) NR-14(St.Khl2M)
mm
0,000 0,092 0,068 0,023 0,062 0,030 0,107 0,050 0,600 0,047 0,088 ff,055 0,244
180 167,5
140--250 0,13--0,23 140--250 0,00--0,05 197--245 0,14---0,50
0,194 0,040 0,400
79,8
1~248
0,379 0,050
78,5
149 115--245
2 3 3 3 2
2
(in %)
mm)
0,00 0,05--0,11 0,02--0,11 0,01--0,03 0,06--0,62 0,05--0,07 0 25 0,05 0 28--0,6O 0,04--0,05 0,07--0,08 0,04--0,05 0,02--0,27 0,00--0,01
1
4 4 2 2 2 I 1
(in
115--245 194--239 143--246 147~246 246 109--200 244-248 182--t94 t82--194
14 ,49
150 135 96 90,5
0,006
0,,27--0,50 0,05
79,1
* Grade of steel in pump plungers is shown in parentheses.
~ Z
#,9
- IGD 9
~Z
#,7 e,5 o
O
=
vO,S
~S
/ -
,.
I_~--~86~
E g,5E
100 0,3-
--
~ O,Z-
--
O
M
0
N
Z
3
~ 5 6 Fuel No.
7
8
g a
b
e
d
Fig. 1 Fig. 2 Fig. 1. Variation in lubricity of Type T-1 and TS-1 fuels in service and in laboratory tests: 1) VNII NP method, NR-21 pump (St. KhVG); 2) KIIGA method; 3) NR-22 pump (St. Khl2M); 4) NR-21 pump (St. Khl2M); 5) NR-14 pump (St. Khl2M). See Table 1 for fuel number identification. Fig. 2. Average wear of pump plunger spheres, adjusted to 250 h. Pumps: 1) NR-t4 (St. IOaVG); 2) NR-14 (St. Khl2M). Fuels: a) TS-1, Krasnovodsk refinery; b) TS-1, Groznyi refinery; c) TS-I, Ryazan' refinery; d) TS-1, Novo-Yaroslavt' refinery. It wait be seen from Table 1 that all the fuels met the GOST specification requirements. Each of the segregated grades of fuel was used in operating monotypical equipment. The NR-14 lumps had plungers made of St. KhVG or St. Khl2M steel. The other types of pumps had plungers made of St. Khl2M only. * *St. KhVG is a tool steel containing 0.90-1.05%C, 0.80-1.10% Mn, 0.90-1.20~ Cr, and 1.20-1.60% W. St. Khl2M is a tool steel containing 1.45.1.70% C, 11.0-12.5% Cr, 0.40-0.60% Mo, and 0.15-0.30% V - Translator.
185
In Table 2 we have listed actual and average adjusted values for the wear of pump-plunger spheres in service, and also results from fuel tests performed by the VNII NP and KIIGA methods. Since axe pump-running times ranged from 109 to 250 h, all the actual wear values were adjusted to a 250-h basis in order to obtain comparable data. This is based on the assumption that the wear is related linearly to operating time. The slope of the line expressing this relationship is equal to the slope of the line expressing the average wear of the pump plunger spheres as a function of operating time for the given type of pump when operating on mixtures of TS-1 and T-1 fuels.* As can be seen from the data of Table 2, the test fuels differ in lubricity. The type T-1 fuels are the best. But the TS-1 fuels differ among themselves in lubrictty; this is particularly apparerrt for operation of the pumps with plungers of S t. KhVG steel. We see, for example, that the use of TS-1 fuel from the Groznyi, Novo-Ufa, or Novo-Yaroslavr refinery gives average adjusted wear values from 0.38 to 0.6 mm for the plungers made of St. KhVG steel, whereas the use of TS-1 fuel from the Krasnovodsk or Ryazan' refinery gives values of 0.107-0.24 mm). No such differences are observed with the plungers made of St. Khl2M steel, where the wear varied only from 0 to 0.05 mm for the entire group o f T - 1 and TS-1 fuels. The same general relationship is also characteristic for the NR-21, NR-54, and NR-22 pumps, which have plungers made of St. Khl2M steel. The determinations of test fuel lubricity were performed in parallel, using the VNII NP and KIIGA methods. The service data and the results from the qualification tests are in good agreement, particularly when the VNII NP method was used. Certain differences for the NR-14 pumps with St. KhVG plungers are related to the effects of service conditions. The KIIGA method has the best sensitivity in evaluating fuels with good lubricity. The sensitivity of the KIIGA method is lower for fuels wifla poor lubricity. LITERATURE CITED Xe 2.
Khim. Tekhnol. Topl. Masel, No. 5, 55-59(1971). IL T. Aird and S. L. Forgham, Wear, 1__8,No. 5, 361-380 (1971).
*As in Russian original; apparently some material has been omitted. Probably intended to mean that the criterion K in the KIIGA method is a ratio (percentage) of the actual wear to the wear when operating on a standard fuel Translator.
186
