Several combustor concepts were designed and tested to demonstrate significant reductions in aircraft engine idle pollutant emissions. Each concept used a different approach for pollutant reductions: the hot wall combustor employs a thermal barrier coating and impingement cooled liners; the recuperative cooling combustor preheats the air before entering the combustion chamber; and the catalytic converter combustor is composed of a conventional primary zone followed by a catalytic bed for pollutant cleanup. The designs are discussed in detail and test results are presented for a range of aircraft engine idle conditions. The results indicate that ultralow levels of unburned hydrocarbons and carbon monoxide emissions can be achieved

Dodds, W. J.

Gleason, C. C.

Mularz, E. J.

English

NASA Technical Reports Server

" i
L
_:" NASA AVRADCOM 8!_
_'_ ' Techmcal Memorandum 78875 Technical Report 78-23(PL) _'&
_. (NASA-TM-788751 COMBUSTCR CO_C£PTS FOR I_78-261_3 _
AIRCRAFT GAS i'UI_BZ_F-LOW-POW_a P.LIrSSIONS ;_
, REDUCTION (NASAl 20 p HC A32/_I_ A01CSCL 20E UnclasG3/C,7 23301
COMBUSTORCONCEPTSFORAIRCRAFTGASTURBINE
LOW-POWERMISSIONSREDUCTION
E. J. Mularz
Propulsion Laboratory
AVRADCOM Research and Technology Laboratories
Lewis Research Center
Cleveland. Ohio r ._,..,i_,_
Aircraft Engine Group _,,_ !:.,:..,_ [:: :'.fr .,:,'
General Electric Company _:,.__ _,'_<'2_:')/ _[
Evendale, Ohio w<ktL _2'_._1_,,%."-'_ -_
, TECHNIC&L PAPER-to be presented at the
Fourteenth Propulsion Conference
' cosponsored by the American Inst, tute of Aeronautics
and Astronautics and the Society of Automotive Engineers
Las Vegas, Nevada, July 25-2'1, 1978
1978O182OO
https://ntrs.nasa.gov/search.jsp?R=19780018200 2020-03-22T02:54:27+00:00Z
t i i : ' : +' + _ _ .... '
i -:i!,
_ National Aeronautics and Space Administration'" -_ ": Lewis Re-_earuh Ce.ter
C]eveiemd, Ohio 441.55
/bstract The EPA also promulgated standards for newly
, certified aircraft gas tu_ .e engines with a corn-
Three combustor concepts have been designed and pliance date being January I, 1981. These emission
tested to demonstrate slgniflca:_ reductions in air- standards are also shown in table i_ indicatin3 a
craft engine idle pollutant emissions. Each concept further reduction in HC mnd CO from the 1979 stand-
, used a different approach for pollutant reductions: erda. Since most of the HC and CO pollutants over
the Hot Wall Combustor employs a thermal barrier the landlng-_akeoff cycle occur during the idle mode
coatlng and impingement cooled liners, the Recuper- of the engine, further significant reductions of HC
ative Cooling Combu.,torpreheats the air before and CO are required at idle conditions than were
entering the combustion c.h_erp and the Catalytic demonstrated during the ECCP program. To Investi-
Converter Combu.tor is composed of a corventJonal gate methods of further improvement at idle, there-
-_- _ * .... tore, Lewis Research Center awarded a contract en-primary zone followed bv a oae.al_!c _ .a- _,_-
rant cleanup. The designs are discussed in detail t_tled the Aircraft Gas Turbine Engine Low-Power
and test results are presented for a range of air- Emissions Reduction Technology, Program (LOFER).
craet engine idle conditions. The results indicate
that ultra-low levels of unburned hydrocarbons and This paper _ummarizes the results of the LOPER
=a_bon munoxiae emissions can be achieved with this program. Details of the cambustor designs and a
technolo_, comprehen_,ve listing of the data has been omitted.
Rather_ the purpose of this paper is to discuss the
techniques used for pollution reduction and to high-
Introduction light the major results of the program. More de-
tailed information may be found in reference 2.
This paper su_m_arlzesthe results of a program
¢D
o to evolve and demonstrate combustor technology di-(D
reefed toward reducing pollutant emissions from air- Loper ProKram Description
craft gas turbine engines during idle operation.
The purpose of the LOPER program was to evolve
Cc_cern over air pollution has drawn the atten- advanced aircraft gas turbine engine technology
tlon of combustion engineers to the quantities of capable of reducing low power emissions of CO and HC
exhaust emissions produced by aircraft gas turbine to levels significantly lower than that which can be
e_gi_es. Two geueral areas of concern have been ex- achieved with current technolo_. The emission
pressed: Urban pollution in the vicinity of air- goals of the program are shown in table II. These
ports and pollution of the stratosphere. The prin- emission index values are representative of the
cipal urban pollutants are unburned hydrocarbons levels required at the engine idle condition in ar-
(HC) and carbon _noxi_ (CO) during idle and t&xl, der to meet the 1981 EPA standards. For comparison
and oxides of nlt_6en (_Ox) and smo_e during take- purpones_ the idle emission goals of the ECCP pro-
off and landing. Oxides of nitrogen formed during gram are also shown along with idle emissions from
altitude cruise of an aircraft are also considered two current comnerclal aircraft engines. One man
pollutants of concern. NASA Lewis _search Center see from the table that the LOI_R program goals for
is eng_d in in-house researah_ university grants_ CO and HC are much lower than the ECCP pro6ram
and industry contracts to reduce the levels of these goals_ and require large reductions in the emission
l_llutants, values of the current engines. These CO and HC
emission index goals would result in a combustion
In Lg?O_ the Clean Air Act charged the Ear|- e_A_cienc_ at idle of 99.7 percent.
ron_ental Protection A_enc_ (EPA) with the respousl-
b_ll_ to establish acceptable exhaust emission Although this program does not focus on N_re-
_e_els of these pcdAutants for all types of aircraft ductton_ a gceA is specified for 1_ x st idle
er _. In ze_ to this _ the EPA pro- tions in order that I_0x - CO tradeoffs are not teed.
_ted _e etandar_ _es_ribed in reference 1, Such tradeof£s could reduce CO at idle to the detrt.
_lth t_ f_t _ia_ce date beiag Jant_ry I, _mt of the NOx li_itatioas imposed by the EPA
187_. Then ead|s_n _ for Class T_ on- standard_ at idle and other operating cc_dSti_us.
_i-*s IN shown in ta_,e I in _em_ of _ EPA pa-
z_r_ _ _ a _i_d _tl_ _ _a- Three _m_mtor maa_pts _m to he _mt_
s_om_ over • pawsc_Ahed land_g-takeo_ _e. In and tested at the operatin_ eo_ditioas g_ven in
_ase to t_N _PA e_ s Lewis _ch table II_. A eln@le @esi_n co_dition vu _pecifled _
t Ce_e_ generated the _xperl_ntal _ C_bustor as shown and is repreceot&t/ve of the engine %die
1_o_ (F_P) e_ the Pollution l_ech_otl_ Ten.l- _litlon of an advanced gas turbine, In additl_
-.: I:_._ tO dr_t'elop tt_lnololD, _ht_h could he ta_tin_ vU to be per_o_d at two other Nta of _-
_d in _are _u tt_btne eae_n_t_ dSsLlus. Then let _mseu_e _md te_erature_ P. atmosl_eres_ _ _,
• i_'r,_ _ _ _I_ _ _M_d sad have _- a_d • at_o_se •78 _ am well an at • total of
tr_d Id_% sl_n_eaat red_etl_n_ in pellutant 3 reflre_ce velOeitle| sad a ra_e of fl_l-alr
e_s'_A m _sible mt_@s An _ to more ec_letel_ doe_ent the 14.14
• -.. __ of eaeb o_m_tor censer,
_,_ _,_,a_, _.s.Ar_a_ _mm_to_, (AVaA_Ca).
•'++;++;, o, ORIGINALPAGEIS
:" " z OFFOOltQUALr
1978018200-002

1978018200-004
5o l'cwre:Ithours. Acknowled6ement ,
"he Recuperative Cooling Ccmbustor exhibits This program was performe4 under NASA contra_:t
more complex aerodynam/cs than Concept I. Since all NAS 5-20[.,80by the Aircraft Engine Group of General
the pr%m-try combustion air must first pass through Electric. Mr. A. L. Meyer wa:_ Program Man_ffer Fred
the liner walls, there is less pre:;stlredrop a_aiJ- Mr. D. W. Bahr served az ]2chniJal Program Manager
able for the fuel atomization process. This resul _ for the contractor. The program was directed out of
in a less efficient fuel atomizer than the oIleuse¢l the Combustion and Ibllution Research Brench of the
in Concept I. Nevertheless, emissions were quite Airbreathin6 Engines Division at the Lewis :_enearch
• low, and approached or were lower t_mn the program Center.
•oals. The temperature of the inlet air was signif-
' _p.tlyincreased by thlz design. For example, at
the design condition of table [[I, the temperature References
' increase of the air was 74 K.
1. "Control o£ Air Poll,z_io,_i'orAircraft Engine_ -
The Catalytic Converter Combustor also exhibits Emizsior Stanuards ano Test Procedures for Air-
more complex merodynamlcs than Concept i. the tern- craft," Federa_ ReKlster, Vol. 38, July i7,
perature of the gases approaching the catalyst bed 197_5,;p. 19088-i_I03.
must be carefully controlled to prevent catalyst
bed damage. The combustor length had to be in- 2. Gleason, C. C., Dodds, W., and Bahr, D. W.,
creased in order to better control these gas tem- "Final Report, Aircraft Gas Turbine Engine Low-
p_ratures, althou6h fuzt/,erwork mig_htresult in a Power F_cissionsReduction Technology Program,"
shorter fen th. Once again less pressure drop was NASA Contract No. NAS _x-_O_80,to be published.
available f, " _uel atomization than _ith Concept I,
-- because of _ne required presmLre aro9 of the cata- _. Butze, H. F. aria Liebert, C. H., "Effec_ of Cera-
lyst bed. In spite of these features, the emissions talcCoating of JT8D Combustor Liner on Maximum
were very low, well below the program goals, and Liner Temperatures and Other Combustor Perform-
tbls Concept does warrant further interest. During ance Parameters," NASA TM X-73_81, 1_76.
the tests there were some problems with catalyst
bed durability. Local hot zones caused bed deterlo- 4. "Procedure for the Continuous Sampling and Mea_-
ration in small spots which did not affect overall urement of G_seous Emissions from Aircraft Tur-
performance. And the initial design of the be_ sup- blne Engines," Aerospace Recommended Practice
port resulted in cracking of the bed in early tests. 1266 SAE, 1971.
NO bed cracking was evident using a modified design
of the bed support. 5. Gleason, C. C., Rogers, D. W., &nd Bahr, D. W.,
"Experimental Clean Combustor Program, Phase
II," General Electric Co., Cincinnati, Ohio,
Summe_-yof Results R?6AEG422, Aug. 1976 (NASA CR-134971).
A program which focused on reducing alrc_ft 6. Roberts_ R._ Peduzzi, A., and Vitti_ G. E., "Ex-
engine idle pollutant emtnions was performed with perimental Clean Co_ustor Program, Phase II,"
the goal of demonstrating advanced technolosy which Pratt and Nhitcey Aircraft, East Hartford,
can later be applied to future cembusti_ _stems. Corm., I'WAS418,Nov. I_76 (KASA CR-154969).
Three eombustor concepts were designed sad tested
at idle conditions typical of ettrremt and future
aircraft _s turbines. Each concept used a differ-
e_t appromch for pollur_ult reductions: A the_
barrier e_t_ of the llners, proheatin_ the com-
bustion air, and a catalytic clean up device. Final
te_t results indicate that all three concepts dmm-
on_trated the ability to achieve substantial reduc-
tic,u in idle emlssion_. All three concepts ex-
hibited _saions of ttaburned hydrocarbons, r_c_
_xt@e_ and oxides of nitro_n which met or were
corre, to lmw_mt _PA1901mlsslo_ ,tea_. Of the three _
e_acapta, the Hot Wall C_mbu_tor, which e_s • i!
thermal barrier eo_tta_ _nd impin_at oooled
ltae_|, _ta_d tl_ lowest mmLu:ieas, At *_
de_l_n _me_Lttiem of an inlet t4mm_mre of 433 _,
aa inlet )pn_su.,.eof 304 _, • reference veloelt,lr
Of 85 _ee, ud a d_l'adX' rmtlo Of 0.010_
: ,_m_ _m,e_ NC- O.S Ig_4 t_l, CO- 1._ S/kS
fm_, u_ sic,,.2.S _ tml. _ sJa_I.$o_T@,Of
__':i:_ (_tal_ie Om_ _ ale@exhibit_NI _u- ..
OF_ oo_xq:_ are _ omt_x thu tim
tim fo_ t_ir pollutioa redu_tt_ potential.
4
1978018200-005
i I
!
T_.BLE I. - CURRENT EPA EMISSION STANDARDS FOR T2
AIRCRAFT ENGINES
[Over a prescribed taxi/idle-takeoff-climbout-
approach-taxi/idle cycle: ib/lO00 ib thrust-
hi-/cycle. ]
1979 1981
Ste_dards Standards
Unburned b4drocarbons O. 8 O. 4
Carbon monoxide 4.3 3.0
Oxides of nitrogen (as NO2) 3.0 _.0
,_ TABLE II. - POLLUTANT EMISSIONS GOALS _T ENGINE IDLE CONDITIOn,S
_9
[In terms of emission index, ,_/kg fuel. ]
i
[ _ Program ECCP Current Current
goals goals CF6-50- JT9D-7 +
Total hydrocarbons, HC 1 4 30 22
Carbon monoxide, CO i0 20 73 47
Oxides of nitrogen, NON _<4 -- 2.5 3.9
*Ref. 5.
+Ref. 6.
TABLE III. - COMBUSTOR OPERATING C0_DITIONS
Design Parametric test
condition condit ions
• Inlet pressure, arm 5 2 3 4
Inlet temperature, K 422 366 422 4?8
Reference velocity, m/sec 22.9 15.2, 22.9, 30.5
Fmel-air ratio 0.0105 0.006 to 0.0134
• Ccmbustor pressure drop, 5.0 ...............
mVP (l_rcent)
] 9780] 8200-006
b I
TABLE IV. - LOW EMISSION COMBUSTOR DESIGN CONCEFfS
i. Hot wall concept
Refractory coated surfaces
Minimized wall quenching
2. Recuperative cooling concept
Preheated primary air
Increased combustion reaction rates
3. Catalytic converter concept
Precombustion and catalytic cleanup
Rapid residual CO and HC consumption
Catalyst bed defined and fabricated
under subcontract with En_lhard M & C Corp.
4. All concepts
Impingement cooled liners, no film cooling
Air blast fuel injectors
Near Stoichiometric prizm_ry zone equivalence ratio
Dilution air admitted far down combustor length
Cor_non dome assembly
Common aft dilution-transition assembly
TABLE V. - TEST RIG DESIGN DETAILS
• 60° Sector combustor rig (S nozzle CF6-_0/ECCP)
• 7.62 am (3.0 in.) dome height
• Reference velocity defined by:
Combu_tor airflow divided by the combustor inner
dome area and the inlet air density:
Wcomb
Vr =
Ad_ _S
With this definition:
C_"6-,50,.. 23,,5 m/s (77 f_S)_
C_6 ,, 16.5 m/s (S4 fps) J At idle
e29.2 cm (iI._ in.) burning length
Co_ed with:
CT6-50 - 33.3 cm (13.l in.)
CFMS6 .. 2Z.9 cm (9.0 in.)
• Cylindrical ccabustor walls (for catalyst configuration)
• • Five element fixed exit rakes
Spaced in-l_ and between fuel nozzle loc&ttona (7 total)
Combination pressure/temperature/gas sa_e E
I1978018200-008
'7
,_ SHELLSWlTHIMP INGEMENT n
i ,_q " r _ "
FUEL_W_RLERS" "
' tR ......
f PRIMARYDILUTION
SECONDARY
DILL[ION
_a)CONCEPTNO. 1 _HOTWALLCOMBUSTOR).
SHELLSWITH IMPINGEMENT _ !
COOLEDLINERS __ __,___ I
:WIRLERAIR _,_ i
i_ WITH ENHANCED_ - = _ ..... - __ _--, ,_-
P_IMARY DILUTION
AIR WITH ENHANCED SECONDARY _, /
TEMPERATURE DILUTION
(bICONCEPTNO, 2(RECUPERATIVECOOLINGCOMBUSTOR),
SHELLSWITH IMPINGEMENT HONEYCOMB '
CO0_O LINERS_ CATALYSTBED"7
; SWIRLER$'_
FUELINTO INITIAL1,
, SIMPLEX"" BURNING
! NOZZLES ZONE
i SWIRL /
CUPAIR-"*"
;i
.,..O,LOT,. i'-*_" DILUTION
/: Ic) CONCEPTNO. 3 (CATALYTICCONVERTERCOMBUSTORI
! :Figure L Schematicof three combustorconcel_s.
t
19780"18200-009
.i
i_ I _
l:
A IR BLAST
FUELINJECTOR
ASSE/V_LY--.,
DOMECOVERFOR
RECUPERATIVE o ,_
ooc, o ! :0: I'_ ONLY--,f _ 0
COOLIDOME ° i
t O
0
' _ -'-- PRI MARYf 0 /
o " DILUTION
• THIMBLES ,
LINERIMPINGEMENTAIR -" ° ° " I
Figure2. - Impingementcoolingcircuit
f' -
!
t
Figure3a. - Combustorassembly,exteriorview.
1978018200-011
-._ _ _ IIIIIIIII - - ' --J -- ..... "qI'qJam_D,_,gmnB _nmp I n .
1978018200-012
figure 3c.-Combustor dome. showing triple wall construction.
I
I
' ORI6/h_AI.p 1a_F ' • " 1_
Poor QU,_I.I,
'i i
'g!!
1978018200-013

EXIT INLET
RAKE
v
RAKE
,i
i ,
! \
!
i Figure5. - Typicalcombustorexit rake(thermocouplelpressurelgas
sample)and Inlet rake(thermocouplelpressure).
i
ORIGNAEPAGEIS
OFPOOR QU_J.,II_
1978018200-015
1978018200-016

,,e
I
!
J
sI J
. _ 304 422 15 i
"i _ _ 6-- 0 _04 422 23 -_
2-_ _k_L___i_°°_
.,J
_ "a, 15
I
!.?
. 5
' 0 [ I
• _! lO--
_ 6-- !,
2 FIA
I I I 1 I
"_ 06 8 I0 12 14
FUEL-AIRATIOx 103
' _ ': FigureS.- Pollutantemissionsfromcatalytict
i i '_ • convertercomustorIC/).
q ;
e
. i
i
INI, w IIIII.L .......... -- _ILILI . . IlL. I' ,_mmw,mmmD-,,,,--,-_ -_,-_,.,m _ _ __ i j .___ .,_
i
] 9780] 8200-0] 8
• STA(;C,FRFDPRIMARY N
_ IMPROVEDNONWALL
r ;
la) CONCEPTNO. 1, CONFIGURATIONH4IHOTWALLCONSUSTORL
PRIMARYDIRECT ,_1DILUTIONRELOCATED-__ _.. .......
.--IMPROVEDNON WALL
-" " WEI"rlNGFUELINJECTOR
(b)CONCEPTNO.2,CONFIGURATIONR/I RECUPERATIVECOMBUSTOR).
.,- PRIMARYDILUTION
/I
.." , LOCATEDFURTHER
.." / DOWNSTREAMOF r- HONEYCOMBCATALYSTBED,
/ / 600SECTOR
-" , DOME
/ *' / /
.,/ I /
I1_ FRONTENDOF
COMBUSTORLENGTHENED
FROM8. 3TO )9.4 cm
IMPROVEDNONWALL
• WETTINGFUELINJECTOR
(c)CONCEPTNO. 3,CONFIGURATIONC7(CATALYTICCONVERTERCOMBUSTOR).
Figure9. - Final configuratio,,o! e_chcombustorconceptexhibitingbestemissionsresults.
ORIONAL PAOF] IS
OF POOR QUAI,I_¥
]9780]8200-0]9
3; '_'
_ ,
0 L,J <:[
80--
--'--1
,-J
m I
d
!
i ,
S
_,, ,
o 3_
z
D1
2- 1 '\
o ;
z
0 '
CURRENT ECCP LOPER
PRODUCTION PHASEIII COMBUSIORS
Figure10. - Comparisonofidleemissionsofcurrentprnduction
enginesandExperimentalC eanCombustorP ogramengines
withcombustorrig emissionsof LOPERcombustorsatnominal
idledesigncondition:304kPa,422K, VREF• 23mlsec,fuel-
air ratio• O.0105.
1978018200-020


Combustor concepts for aircraft gas turbine low-power emissions reduction

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