The effects of select fuel property variations on two major engine classifications are summarized. Thirteen refined and blended fuels were used which exhibited significant variations in hydrogen content, aromatic type, initial boiling point, final boiling point, and viscosity. Trends were very similar but the degree of fuel sensitivity was not constant. For both systems the dominant fuel property during high pressure operation was found to be fuel hydrogen content. For operation at low pressure test points the fuel volatility and viscosity became the dominant fuel properties for both systems. Aromatic type and final boiling point did not significantly affect combustion data. Correlations of other fuel properties with these and other performance parameters are presented

Jackson, T. A.

English

NASA Technical Reports Server

FUEL CHARACTER EFFECTS ON THE 579 AND FlOl  ENGINE COMBUSTION SYSTEMS 
Thomas A. Jackson 
Aero Propuls ion  Laboratory 
Wright-Pat terson A i r  Fo rce  Base 
Between 1977 and 1978 t i m e  per iod  f o u r  c o n t r a c t u a l  e f f o r t s  were i n i t i a -  
t e d  t o  e v a l u a t e  t h e  e f f e c t s  of select  f u e l  p rope r ty  v a r i a t i o n s  on s e v e r a l  
major  engine  c l a s s i f i c a t i o n s .  The engines  t h a t  would be most widely used by 
t h e  A i r  Force  through t h e  nex t  decade were d iv ided  i n t o  t h r e e  c a t e g o r i e s :  
low p res su re  r a t i o ,  cannu la r  combustion system; h igh  p res su re  r a t i o ,  annu la r  
combustion system; and high p res su re  r a t i o ,  cannu la r  system. The f o u r t h  
program involved a n  advanced combustion system. 
The f i r s t  two c a t e g o r i e s  were represented  by t h e  579 and t h e  FlOl  gas  
t u r b i n e  engines ,  r e spec t ive ly .  T h e  t h i r d  ca tegory  was represented  by the  
TF41 engine.  T h i s  system w i l l ,  however, n o t  be d i scussed  as t h e  e v a l u a t i o n  
i s  no t  f i n i shed .  The c o n t r a c t s  t o  eva lua te  f u e l  e f f e c t s  i n  t h e  579 and F l O l  
systems were awarded a t  about t h e  same t i m e  t o  t h e  same company, General  
E l e c t r i c .  Both programs were cofunded by t h e  Aero Propuls ion  Laboratory and 
t h e  A i r  Force  Engineer ing S e r v i c e s  Center.  The e f f o r t s  were timed t o  run  
concurren t ly .  Thus, t es t  f u e l s  used on t h e  program were i d e n t i c a l .  
A l l  t e s t i n g  w i t h i n  both e f f o r t s  was conducted on component r i g s .  The 
t e s t  r i g s  and t h e  t e s t  p o i n t s  were e s t a b l i s h e d  t o  e v a l u a t e  t h e  e f f e c t s  of 
f u e l  p r o p e r t i e s  on t h e  s t a t i c  performance, t h e  i g n i t i o n  and s t a b i l i t y  l i m i -  
t a t i o n s ,  t h e  carboning and f u e l  nozz le  f o u l i n g  t endenc ie s ,  and t h e  du rab i l -  
i t y  of each combustion sys tem.  S t a t i c  performance w a s  measured a t  f o u r  op- 
e r a t i n g  cond i t ions :  i d l e ,  c r u i s e ,  t a k e o f f ,  and dash. P a r t i a l  s c a l i n g  of 
i n l e t  a i r  p re s su re  and mass f low w a s  necessary f o r  t h e  579 dash  c o n d i t i o n  
and t h e  FlOl t akeof f  and dash  cond i t ions .  I g n i t i o n  p r o p e r t i e s  were evalua- 
t e d  a t  s tandard  and c o l d  day ground c o n d i t i o n s  as  w e l l  a s  a t  s e v e r a l  p o i n t s  
of t h e  a l t i t u d e  windmi l l i ng / r e l igh t  requirement map. S t a b i l i t y  w a s  evalua- 
t ed  by determining t h e  f u e l  l e a n  blowout p o i n t  and t h e  p re s su re  blowout 
p o i n t  a t  s e v e r a l  ope ra t ing  po in t s .  Carboning and f u e l  nozz le  f o u l i n g  t es t s  
were conducted i n  s p e c i a l  r i g s ,  opera ted  a t  special  cond i t ions ,  s e l e c t e d  t o  
a c c e l e r a t e  t h e s e  phenomena. I n  a d d i t i o n ,  hardware l i f e  p r e d i c t i o n s  were 
made of t h e  combustor l i n e r  (based  on metal temperature  measurements) and of 
t h e  t u r b i n e  (based on r a d i a l  temperature  p r o f i l e  and p a t t e r n  f a c t o r  measure- 
ment s) . 
T h i r t e e n  r e f i n e d  and blended f u e l s  were used i n  t h e s e  programs. 
f u e l s  e x h i b i t e d  s i g n i f i c a n t  v a r i a t i o n s  i n  hydrogen con ten t  (12.0 t o  14.5 
weight p e r c e n t ) ,  a romat ic  type  (monocyclic o r  b i c y c l i c ) ,  i n i t i a l  b o i l i n g  
p o i n t  (285 t o  393 K by g a s  chromatograph), f i n a l  b o i l i n g  po in t  (532 t o  679 K 
a l s o  by g a s  chromatograph), and v i s c o s i t y  (0.83 t o  3.25 mm2/s a t  300 K). 
These 
83 
https://ntrs.nasa.gov/search.jsp?R=19800020811 2020-03-21T03:23:01+00:00Z
The r e s u l t s  v a r i e d  between t h e  two programs. Trends were very similar 
but  t h e  degree  of f u e l  s e n s i t i v i t y  w a s  no t  cons t an t .  For both  systems t h e  
dominant f u e l  proper ty  du r ing  high p res su re  o p e r a t i o n  w a s  found t o  be f u e l  
hydrogen content .  For t h e  579 t h i s  f u e l  proper ty  s t r o n g l y  a f f e c t e d  smoke, 
carbon depos i t i on ,  l i n e r  temperature  (and ,  t h e r e f o r e ,  l i n e r  l i f e ) ,  and flame 
r a d i a t i o n  and moderately a f f e c t e d  NOx emissions.  For  t h e  FlOl  system hy- 
drogen con ten t  s t rong ly  a f f e c t e d  smoke emissions,  l i n e r  temperature  (and 
l i f e ) ,  and NOx emissions.  
For  o p e r a t i o n  a t  low p res su re  test p o i n t s  t h e  f u e l  v o l a t i l i t y  and v is -  
c o s i t y  became t h e  dominant f u e l  p r o p e r t i e s  f o r  bo th  systems. 
ground s t a r t i n g  and a l t i t u d e  r e l i g h t  c a p a b i l i t i e s  of t h e  systems were de- 
graded wi th  reduced v o l a t i l i t y  and increased  v i s c o s i t y .  Typica l ly ,  t h e  10% 
recovery temperatures  of t h e  f u e l s '  d i s t i l l a t i o n  behavior  were used as a 
measure of f u e l  v o l a t i l i t y .  V i scos i ty  w a s  in t roduced  i n t o  t h e  c o r r e l a t i o n s  
through t h e  r e l a t i v e  S a u t e r  Mean Diameter (SMD), a parameter c h a r a c t e r i z i n g  
t h e  f u e l  spray. 
c o n d i t i o n  of i n t e r e s t  and re ferenced  t o  t h e  SMD of JP-4. The F l O l  w a s  more 
s e n s i t i v e  than  t h e  579 t o  v a r i a t i o n s  i n .  t h e s e  parameters.  
The c o l d  day 
These v a l u e s  were c a l c u l a t e d  f o r  each  tes t  f u e l  a t  each  
The FlOl f u e l  d i v i d e r  va lve  i n d i c a t e d  a s e n s i t i v i t y  t o  t h e  f u e l  thermal  
s t a b i l i t y  i n  an  a c c e l e r a t e d  c y c l e  t es t  involv ing  two f u e l s  of widely d i f f e r -  
e n t  thermal  s t a b i l i t y  p rope r t i e s .  
i n d i c a t e  a c o r r e l a t i o n  of l abora to ry  measured f u e l  thermal  s t a b i l i t y  and t h e  
c y c l e s  t o  a d i s c r e t e  deg rada t ion  i n  t h e  o p e r a t i o n  of t h e  FlOl  f u e l  d i v i d e r  
va lve ,  a r b i t r a r i l y  chosen t o  be a 10% i n c r e a s e  i n  f low h y s t e r e s i s  a t  a f u e l  
p re s su re  drop of 1.24 MPa. 
no apparent  f u e l  s e n s i t i v i t y  over  t h e  range t e s t e d .  
t h e  579 f u e l  nozz le  passages  are not  as  c r i t i c a l l y  dimensioned as those  of 
t h e  F101. 
The tes ts  were no t  conclus ive  but  d i d  
Rela ted  t e s t i n g  of t h e  579 f u e l  nozz le  ind ica t ed  
Th i s  was expected s i n c e  
Aromatic t ype  and f i n a l  b o i l i n g  po in t  do  n o t  s i g n i f i c a n t l y  a f f e c t  com- 
b u s t i o n  da ta .  
C o r r e l a t i o n s  of o t h e r  f u e l  p r o p e r t i e s  wi th  t h e s e  and o t h e r  performance 
parameters were examined. The above r e l a t i o n s h i p s ,  however, were t h e  most 
dominant. 
AFAPL-TR-79-2015 and AFAPL-TR-79-20 18, r e spec t ive ly .  
Detai ls  of t h e  579 and F l O l  f u e l  e f f e c t s  programs c a n  be found i n  
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L i m i t s  Below T e s t  L i m i t s  (239K) 
- 00” 
0 JP-4 Based Fuels 
0 JP-8 Based Fuels 
A No. 2 Diesel Fuel 
I 1 
0.9 1.1 1 e 3  1.5 1 
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2500 rpm Cranking Conditions 
P3 w 101 kPa 
Wc = 1.15 kg/s - Engine 
340 380 420 460 500 
Fuel 10 Percent Recovery Temperature, K 
(Gas Chromatograph Simulated Dist i l la t ion)  
7 
Figure 1 e E f f e c t  of Fuel Atomization and Volat i l i ty  on Cold Day Ground 
Starting Capability. 
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Flight Mach No. = 1.25 I 
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Figure 2 . Effect of Fuel Atomization on Altitude Relight Limits (Open 
Exhaust Nozzle Windmilling Conditions). 
88 
80 
60 
40 
0.9 1.1 1.3 1.5 1.7 
80 
60 
I Tailed Symbols: 
Monocyclic Aromatic Blends 
500 
40 
340 380 4 20 460 
Fuel 10 Percent Recovery Temperature, K 
(Gas Chromatograph Simulated Distillation) 
Figure 3 . Effect of Fuel Atomization and Volatility on Idle CO 
Emission Levels. 
~ 
89 
100 
80 
60 
40 
20 
- 0 JP-8 Based Fuels 
&No. 2 Diesel Fuel 
1 Tailed Symbols: 
Honocyclic Aromatic- 
Blends I I 
11 12 13 14 15 11 12 13 14 15  
Fuel Hydrogen Content, weight percent 
Figure 4 Effect  of Fuel Hydrogen Content on Smoke Emission Levels. 
90 
T L - T ,  
FUEL H CONTENT, WT % 
PREVIOUS DATA 
TSS/J79/JTSD/CJ805/157 
0 JP4 BLENDS 
0 JP-8 BLENDS 
A D M  
TAILS INDICATE MONOCYCLIC BLEND 
Figure 5 .  Ef fec t  of Fuel Hydrogen Content on Liner Temperature 
Parameter a t  Cruise Operating Conditions. 
91 
Hydrogen content, % by w t  
Figure 6 .  Effect of fue l  hydrogen content on 
combustor durability. 
92 
200 
100 
50 
20 
10 
5 
2 
1 I I I I 
Tsp = Fuel Breakpoint by Visual Tube Rating (JETOT) 
Tft = Fuel Temperature i n  Nozzle Valve Gumming T e s t  
0 JP-4, TBp =: 538 K 
- 0 JP-8, TBp = 561 K 
Failure Occurred 
Before F i r s t  
Calibration 
20 40 60 80 100 120 140 160 
(TBp - Tft) , Temperature Difference, K 
Figure 7 E f f e c t  of Fuel Temperature and Type on Fuel Nozzle Valve  
L i f e ,  
93  


Fuel character effects on the J79 and F101 engine combustion systems

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