An overview of combustor technology developments required for use of broadened property fuels in jet aircraft is presented. The intent of current investigations is to determine the extent to which fuel properties can be varied, to obtain a data base of combustion - fuel quality effects, and to determine the trade-offs associated with broadened property fuels. Subcomponents of in-service combustors such as fuel injectors and liners, as well as air distributions and stoichiometry, are being altered to determine the extent to which fuel flexibility can be extended. Finally, very advanced technology consisting of new combustor concepts is being evolved to optimize the fuel flexibility of gas turbine combustors

Niedzwiecki, R. W.

English

NASA Technical Reports Server

COMBUSTION TECHNOLOGY OVERVIEW 
Richard W. Niedzwiecki 
Nat iona  1 Aeronaut ics  and Space Admini s t  ra t ion  
L e w i s  Research Center  
The combustion of  g a s  t u r b i n e  f u e l s  i s  t h e  s u b j e c t  mat te r  f o r  t h e  next  
two sess ions .  I n  t h e  papers  i n  t h i s  s e s s i o n  combustor technology programs, 
as  d i s t i n g u i s h e d  from combustion r e sea rch  of a more fundamental na tu re ,  are 
d i scussed ,  and t h e  r e s u l t s  of Government-funded c o n t r a c t s  w i t h  engine  manu- 
f a c t u r e r s  are descr ibed .  
To evolve t h e  combustor technology r equ i r ed  f o r  u se  of broadened- 
proper ty  f u e l s ,  several l e v e l s  of combustor technology are being inves t iga -  
ted.  F i r s t ,  unmodified in-serv ice  combustors are being eva lua ted  w i t h  
broadened-property f u e l s .  The i n t e n t  of t h e s e  i n v e s t i g a t i o n s  i s  t o  de t e r -  
mine t h e  e x t e n t  t o  which f u e l  p r o p e r t i e s  cah be v a r i e d ,  t o  o b t a i n  a d a t a  
base of combustion - f u e l  q u a l i t y  e f f e c t s ,  and t o  determine t h e  t r ade -o f f s  
a s s o c i a t e d  wi th  broadened-property f u e l s .  Second, subcomponents of in- 
s e r v i c e  combustors such as  f u e l  i n j e c t o r s  and l i n e r s ,  a s  w e l l  a s  a i r  d i s t r i -  
bu t ions  and s to ich iometry ,  are being a l t e r e d  t o  de te rmine  t h e  e x t e n t  t o  
which f u e l  f l e x i b i l i t y  c a n  be extended. L a s t ,  very  advanced technology 
c o n s i s t i n g  of new combustor concepts  is being evolved t o  opt imize  t h e  f u e l  
f l e x i b i l i t y  of g a s  t u r b i n e  combustors. 
The inc reas ing  concerns  regard ing  t h e  supply and q u a l i t y  of g a s  tu r -  
b i n e  f u e l s  a t  p re sen t  and f o r  t h e  f u t u r e  has  served as  t h e  impetus f o r  ex- 
panded r e sea rch  i n  many f u e l s  and combustion a reas .  Department of Defense 
programs aimed a t  m i l i t a r y  a v i a t i o n  a p p l i c a t i o n s  form a s i g n i f i c a n t  p a r t  of 
t h e  m a t e r i a l  p resented  i n  t h i s  sess ion .  S p e c i f i c a l l y ,  two A i r  Force  Wright 
Aeronaut ica l  Laboratory (AFWAL) programs are desc r ibed  by Thomas A. Jackson 
of AFWAL. These a r e  t h e  F u e l  Charac te r  E f f e c t s  on t h e  579 and FlOl Engine 
Combustion Systems, a r e c e n t l y  completed e f f o r t ,  and t h e  A i r  Force Fue l  
Mainburner/Turbine E f f e c t s  program, a major program c u r r e n t l y  i n  progress .  
NASA L e w i s  programs aimed toward c i v i l  a v i a t i o n  a p p l i c a t i o n s  inc lude  
a n a l y i c a l  e v a l u a t i o n  of t h e  e f f e c t s  of broadened-specif i c a t i o n  f u e l s  on 
high-bypass tu rbo fan  engine  combustors, which i s  desc r ibed  l a t e r  i n  t h i s  
overview; t h e  Experimental  Combustor Study program, a r e c e n t l y  completed 
e f f o r t ,  which i s  desc r ibed  by John M. Kasper and Edward E. Eksted t  of t h e  
General  Electr ic  Co. ; and t h e  NASA Broadened-Specif i c a t i o n  F u e l s  Combustion 
Technology program, which i s  desc r ibed  i n  t h e  p a p e r s  by James S. Fea r  of 
NASA L e w i s ,  D r .  Robert  P. Lohmann of P r a t t  & Whitney, and Wil lard J. Dodds 
of General  E l e c t r i c  Co. 
A t h i r d  area of f u e l s  and combustion research ,  s ta t ionary-power g a s  
T h i s  program c o n s i s t s  of c o n t r a c t s  w i th  
tu rb ines ,  i s  being pursued i n  t h e  Department of EnergyINASA Low-NOx Heavy- 
Fue l  Combustor Concept program. 
67 
https://ntrs.nasa.gov/search.jsp?R=19800020809 2020-03-21T03:22:49+00:00Z
f i v e  engine  manufac 
menta l ly  accep tab le  
(non-petroleum-deri 
t u r e r s  and i s  aimed a t  evolving fuel-f  l e x i b l e ,  environ- 
ved f u e l s )  i n  u t i l i t y  and i n d u s t r i a l  app l i ca t ions .  A l -  
though a p r e s e n t a t i o n  of t h i s  program i s  no t  inc luded  i n  t h i s  s e s s i o n ,  t h e  
program has  been desc r ibed  i n  a r ecen t  ASME paper  ( r e f .  1 ) .  
combustors capable  of u s ing  heavy o i l  f u e l s  and synfue ls  
Before t h e  NASA L e w i s  combustor technology programs were implemented, 
a n a l y t i c a l  s t u d i e s  were conducted under c o n t r a c t s  wi th  P r a t t  & Whitney A i r -  
c r a f t  and t h e  General  E l e c t r i c  Co. These s t u d i e s  c o n s i s t e d  of in-depth ana- 
l y s e s  of  broadened-property f u e l  e f f e c t s  on t h e  performance and emissions of 
c u r r e n t  high-bypass-rat io ,  commercial a i r c r a f t  engine  combustors and f u t u r e  
engine combustors of t h e  Energy E f f i c i e n t  Engine (E3) type. 
have been completed and t h e  r e s u l t s  publ ished as  NASA Con t rac to r  Reports  
( r e f s .  2 and 3 ) .  
These s t u d i e s  
Study r e s u l t s  i n d i c a t e d  t h a t  i n  convent iona l  combustors t h e  use  of 
broadened-property f u e l s  could  have t h e  fo l lowing  undes i r ab le  e f f e c t s  : 
1. L i n e r  tempera tures  could  be h igher  because of increased  f lame radia-  
Local  l i n e r  tempera tures  could  i n c r e a s e  by as much t i o n  t o  combustor wal l s .  
as  40 kelv ins .  
25 t o  40 percent .  
The h ighe r  tempera tures  could  reduce l i n e r  f a t i g u e  l i f e  by 
2 .  A t t e m p t s  t o  reduce l i n e r  t e m p e r a t u r e s  by provid ing  increased  coo lan t  
a i r f l o w s  could adverse ly  a f f e c t  combustor ex i t - t empera tu re -d i s t r ibu t ion  uni- 
formi ty  and thereby reduce t u r b i n e  l i f e .  
3 .  Broadened-property f u e l s  have poorer  a tomiza t ion  c h a r a c t e r i s t i c s ,  
which would produce poorer ,  less-uniform f u e l  sp rays  and r e s u l t  i n  poorer  
i g n i t i o n  and a l t i t u d e  r e l i g h t  performance, d e t e r i o r a t e d  temperature  d i s t r i -  
bu t ions ,  i nc reased  smoke a t  high-power cond i t ions ,  and h igher  emiss ion  lev- 
e l s  of carbon monoxide and unburned hydrocarbons a t  low-power cond i t ions .  
4. Maximum a l lowab le  f u e l  t e m p e r a t u r e s  could  be reduced by as much as 
1 2  k e l v i n s  because of t h e  poorer  thermal  s t a b i l i t y  of broadened-property 
fue l s .  
Study r e s u l t s  a l s o  i n d i c a t e d  t h a t  t h e  e f f e c t s  of broadened-property 
f u e l s  on combustors could  be minimized by us ing  mult izone,  lean-burning com- 
bus tors .  I n  t h e s e  advanced combustor des igns  t h e  combustion processes  are 
more c a r e f u l l y  c o n t r o l l e d  than  i n  convent iona l  combustors, and r a d i a t i o n  
l e v e l s  t o  l i n e r s  are minimized by burning a t  fue l - l ean  c o n d i t i o n s  du r ing  
high-power opera t ion .  These i n d i c a t i o n s  have been s u b s t a n t i a t e d  i n  test  r i g  
and engine  short- term e v a l u a t i o n s  where convent iona l  combustors and mult i -  
zone combustors w e r e  f u e l e d  w i t h  Jet A and broadened-property d i s t i l l a t e  
f u e l s  ( r e f s .  4, 5, and 6 ) .  
6% 
REFERENCES 
1. L i s ter ,  E.;  Niedzwiecki, R .  W . ;  and Nichols ,  L. : Low NO, Heavy Fuel  
Combustor Program. ASME Paper 80-GT-69, March 1980. 
2. Lohmann, R .  P . ;  Sze te la ,  E .  J . ;  and Vranos, A. : Analyt ica l  Evaluation 
of the Impact of Broad Spec i f i ca t ion  Fuels  on High Bypass Turbofan Engine 
Combustors. NASA CR-159454, 1978. 
69 
AIRCRAFT RESEARCH AND TECHNOLOGY FOR FUTURE FUELS 
COMBUSTORSlENGlNES OBJECTIVE 
IN-SERVICE ASSESS FUEL 
FLEXIBILITY 
DATA BASE 
TRADEOFFS 
IN-SERVICE EXTEND FUEL 
FLEXIBILITY 
NEW CONCEPTS OPTIMIZE 
FUEL FLEXIBILITY 
CAPABILITIES 
IDENTIFICATION * FUEL - FLEXIBLE 
FUTURE FUELS 
AIRCRAFT 
EMPHASIS 
EXAMINE PERFORMANCE 
WITH BROAD PROPERTY 
FUELS 
SUBCOMPONENT 
IMPROVEMENT 
EVOVLE ADVANCED 
COMBUSTION 
TECHNOLOGY 
TECHNOLOGY 
L 0 GUIDANCE TO 
L, FUELS USERS 
& SUPPLfERS 
SYSTEMS ANALYSIS FUEL SYSTEM 
R&T AND 
BROAD PROPERTY TRADE-OFF 5 
r.," c 
B ASTM FUEL 
STUDIES S PECIFICATION 
L I 1 GUIDANCE tuu3 
F U E L S l C O M B U S T l O N  TECHNOLOGY P R O G R A M S  
70 
G A S  T U R B I N E  F U E L S l C O M B U S T I O N  R E S E A R C H  
ORGANIZATION APPLICATION PROGRAMS 
DOD MILITARY AVIATION 0 JT9, F I O l  
AIR FORCE WRIGHT AERONAUTICAL 0 0 FUEL-MAIN BURNER 
/TURBINE EFFECTS LABORATORY 
JOINT EFFORT 
NAS A-LeRC CIVIL AVIATION 0 ANALMICAL STUDIES 
0 COMB. TECHNOLOGY 
~ 0 U P  COMB. STUDY 
COMBINED EFFORT 
n 
DOE 
FOSSIL ENERGY DIVISION 
CS-80-1498 
-LJ- 
STATIONARY POWER 0 LOW NO, HEAVY 
FUEL COMBUSTOR 
0 SYNFUEL CHARACTERIZATION 
AND COMBUSTION STUDIES 
AN ALYT 1 CAL STUDY RESULTS 
IN CONVENTIONAL COMBUSTORS THE USE OF BROAD 
PROPERTY FUELS COULD RESULT IN: 
POORER FUEL S PRAYS 
MAX. FUELTEMP. INCREASED SMOKE & LOW 
POWER CO 8 THC 7 
FUEL EFFECTS COULD BE MINIMIZED BY MULTI-ZONE, 
LEAN BURNING COMBUSTORS CS-80-1321 
71 
INCREASE IN LINER TEMPERATURES WITH ERBS FUEL 
CS-80-1322 
EFFECT OF DILUTION AIR QUANTITY 
ON COMBUSTOR PAllERN FACTOR 
PAlTERN 
FACTOR 
0 5 10 15 M 25 
DILUTION AIRROW, 96 OF COMBUSTOR AlRnOW CS-80-1500 
72 
EFFECT OF HYDROGEN CONTENT OF FUEL 
ON LINER TEMPERATURE 
400 
MAX LINER 
TEMP MINUS 3Ml 
INLET AIR 
TEMP, 
hoc m 
m r  
r CONVENTIONAL 
COMBUSTORS 
- 
- 
- LEXPERIMENTAL MULTIZONE COMBUSTORS 
(FUEL-LEAN MAIN STAGD 
100  
11 12 13 14 15 16 
CS-80-1497 HYDROGEN CONTENT, Wt % 
73 


Combustion technology overview

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