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-___--_ _, =_= ,i ..... Technicai Report 92-C-019
Technical Memorandum 105680
Contingency Power for aSmall_ Turboshafl
_::: Engine by Using Water Injection Into
=_.... Turbine Cooling Air
Thomas J,2 Biesiadny
Lewis Research Center ......... : ......
Cleveland, Ohio
and
Gary A. Klann .............
Propulsion Directorate .................
U.S. Army Aviation Systems Command
2 ---- -- Lewis Research Center ..............
Cleveland, Ohio
2L2 =_ = 2 : 27 2 5 = C£ _ CY .... 2: : = == --".... Prepared fo/the : :
80th Symposium on Heat TranSfcr_a..nd C_fig! n Gas Turbines -_
-i- --: sponsored by theAGARD Propulsion hnd Energetics Pane!i ....
Antalya, Turkey, October 12-16, 1992
SYSTEMS COMMAND _ _
N/ A
-= -_=- z e- :__- # N92-29061 .... =_ (NASA-TM-IO56BO) CONTINGENCY POWER FOR A SMALL TURBOSHAFT ENGINE BY USING WATER IHJECTION INTO TURBINE COOLING AIR (NASA)
Uncl as - -
:- _- _ -- ___ IO p
0110072
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r CONTINGENCY POWER FOR A SMALL TURBOSHAP-T ENGINE BY USING WATER INJECTION INTO TURBINE COOLING AIR Thomas J. Biesiadny National Aeronautics and Space Administration Lewis Research Center 21000 Brookpark Road Cleveland, Ohio 44135 U.S.A.
_nd Gary A. Klann Propulsion Directorate U.S. Army Aviation Systems Command NASA Lewis Research Center 21000 Brookpark Road Cleveland, Ohio 44135 U.S.A.
ABSTRACT analytical feasibility and design (Refs. 5 and 6) as well as the experimental demonstration that is the subject of this report.
Because of one-engine-inoperative (OEI) requirements, The demonstration was on a T700-GE-701 turboshaft engine together with hot-gas reingestion and hot-day, high-altitude as an adjunct to an Army and NASA Small Turboshaft Engine takeoff situations, power augmentation for multiengine rotor- Program (STEP).
craft has always been of critical interest. However, power augmentation by using overtemperature at the turbine inlet Power augmentation by injecting water into the turbine cool- will shorten turbine life unless a method of limiting thermal ing air is not a new concept. Water injection into the turbine and mechanical stresses is found. A possible solution involves cooling air and the combustor is currently being used in the allowing the turbine inlet temperature to rise to augment Rolls-Royce Pegasus engine, the propulsion system for the power while injecting water into the turbine cooling air to Harrier aircraft (Ref. 7). What is new is the application of limit hot-section metal temperatures. An experimental water this technique to a small engine. The study by Van Fossen injection device was installed in an engine and successfully (Ref. 2) showed a large enough payoff in short-term power tested. Although concern for unprotected subcomponents in augmentation to warrant an experimental investigation along the engine hot section prevented demonstration of the tech- with a study of other contingency Power techniques.
nique's maximum potential, it was still possible to demon- strate increases in power while maintaining nearly constant The study by Hirschkron (Ref. 6) showed significant potential turbine rotor blade temperature.
advantage with four contingency power systems, one of which was the water-injection-into-turbine cooling scheme. The four systems were close enough to one another to be competitive INTRODUCTION in a practical engineering evaluation. It is significant to note Power augmentation for multiengine rotorcraft is of critical that water injection into the compressor, which is currently interest for such situations as operation with one engine used for power augmentation on some turbine engines, had inoperative (OEI), hot-gas reingestion, and hot-day, high- lower payoff benefits than these four systems.
altitude takeoff. According to an earlier study (Ref. 1), one method of power augmentation is overspeed and overtempera- Before water injection into turbine cooling air can be given ture at the turbine inlet. However, power augmentation by serious consideration for incorporation into a small turbine using overtemperature at the turbine inlet will shorten turbine engine, a turbine cooling analysis is needed. The program life unless a method of limiting thermal and mechanical stress undertaken and reported herein was an attempt to develop an is found.
experimental data base with which to evaluate the analyses in Ref. 5 and the studies in Ref. 6.
A possible solution to this dilemma (Ref. 2) involves allowing Consistent with the available resources, the demonstration was the temperature at the turbine inlet to rise to augment power while injecting water into the turbine cooling air to maintain confined to a study of water injection into the compressor the hot-section metal temperatures. The latent heat of vapori- bleed air used for cooling the first-stage, high-pressure turbine zation of the injected water is used as a heat sink to cool the blades. These rotor blades were chosen for study because the compressor bleed air that is used for cooling the hot section.
effect on life and the possible consequences during contin- NASA Lewis has conducted a research study into the feasibil- gency power use, with significant increases in temperature, would be more severe than for any other component. The ity of supplementing turbine cooling by water injection during contingency power events on turboshaft engines. This study studies completed on engine cycle, heat transfer, and life included aspects of basic heat transfer (Refs. 3 and 4) and analysis indicated that the concept is feasible. However, the logistics of carrying water for this technique and the modifica- gressed from the supply tank to the distribution ring. The tions to the engine control-for contingency power situations thermocouples and static pressure probes upstream and down- must be addressed before a system can become operational.
stream of the accelerator measured the quality of the steam/air Hirschkron (Ref. 6) describes some of these installation and mixture and determined the mass flow through the accelerator.
operational factors, such as design changes to a baseline The remaining instrumentation on the seals, the turbine noz- engine to incorporate the water injection system and the zles, the turbine shrouds, the turbine nozzle platforms, and the system control and limits. combustor liner was used to observe the condition of the hot section.
The objective of the tests was to demonstrate higher power output of a turboshaft engine while maintaining the turbine Pyrometer blade temperature by injecting water into the turbine cooling air. The results of these tests are presented in terms of the The most important instrument required for the test was an response of augmented power and turbine blade metal optical pyrometer. The pyrometer assembly consisted of a temperature to humid-air cooling during engine operation over photodiode, a lens, and the associated electronics within a a range of power settings. The experimental results of these water-cooled case. Figure 4 shows the location of the pyrom- tests are compared with the analytical results of Hirschkron eter in the engine hot section. It was mounted on a first- (Ref. 5).
stage turbine nozzle segment within the engine midframe and directed at the leading edge of the first-stage turbine blades.
The signal lead and the cooling water supply and return tubing APPARATUS AND PROCEDURE were routed through specially prepared holes in the outer mid- frame housing.
Engine The engine used for the investigation, a T700-GE-701, was The pyrometer system output was connected to an oscillo- a front-drive turbosh,'fft engine. It had an integral particle scope for real-time display and photographing and to a wide- separator, a five-stage-axial-flow, single-stage-centrifugal-flow band frequency-modulated (FM) tape recorder for subsequent compressor, a throughflow annular combustor, a two-stage- data recording and analysis. Also part of the system was a axial-flow gas generator, and a free two-stage-axial-flow once-per-revolution speed signal that was recorded and used power turbine. Figure 1 shows a schematic of the engine. as an index marking to identify specific turbine blades.
Water Injection System Model Tests Figure 2 shows the water injection hardware. This consisted Before the engine test a model test of the water injection of water supply tubing and a water distribution ring installed system was performed to obtain accelerator calibration data, within the engine combustor midframe assembly. The supply to verify assumptions made during conceptual design studies, tubing entered the engine midframe outer housing through one and to gain operational experience with the system.
of two igniter ports. It was then routed around the combustor and under the inner combustor shroud, where it mated with Engine Tests the distribution ring. The 0.250-in.-diameter tubing was enclosed in another 0.375-in.-diameter tube to the point where The conditions under which the engine was tested with the it passed under the shroud. The distribution ring was posi- turbine cooling water injection system are summarized in tioned around a bearing housing directly upstream of the tur- Table I. The water injection concept was initially demonstra- bine cooling air accelerator assembly. Briefly, the accelerator ted at settings below intermediate rated power 0RP). IRP is is a device to accelerate and direct axial flow in a tangential defined as the maximum power setting that can be maintained direction so as to aid flow distribution into the turbine rotor.
The distribution ring, also of 0.250-irh-diameter tubing, con- TABLE [--ENGINE SE'ITINGS FOR CONTINGENCY rained five equally spaced 0.037-in.-diameter holes positioned POWER INVESTIGATION USING WATER-AIR in such a way as to direct the water into the accelerator pas- sages and allow it to evaporate in the turbine cooling air.
TURBINE COOLING Test Identification Water/cooling air Figure 3 shows a schematic representation of the water injec- ratio, tion supply system. This consisted of a pressurized reservoir percent of distilled water, a high-pressure gaseous nitrogen supply, valves, tubing, and system-monitoring instrumentation.
1.0 Shakedown 2.0 Baseline data 3.0 Shakedown of water injection Engine Instrumentation system 4.0 Turbine inlet temperatttre < IRP: The instrumentation used for the engine test program consisted 4.1 Base 0 to 10 both of hot-section instrumentation specifically installed for 0 to 10 4.2 Base + I00 deg F the contingency power tests and of the normal complement of 0to 10 4.3 Base + 135 deg F instrumentation for monitoring engine operation. The hot- 5.0 Turbine inlet temperature > IRP: section instrumentation consisted of thermocouples and static 5.1 IRP 0to 6 pressure taps. The thermocouples on the injector tube were 5.2 IRP+ 0to 6 positioned to indicate the condition of the water as it pro- COMBUSTOR_ T GAS GENERATOR CENTRIFUGAL \ \\TURBINE \ COMPRESSOR --_ \ \ _--POWER \ \ \ \ TURBINE \ \ \ \ PARTICLE
1 _=_s_°_ll I I I
I INLET SEPARATOR q FIG. 1 SCHEMATIC OF ENGINE, r-WATER SUPPLY TUBE I !
I I !
\ \ \ _--WATER DISTRIBUTION RING CD-86-21130 FIG. 2 WATER INJECTION SYSTEM INSTALLED IN ENGINE.
(_PRESSURE _{./-- VENT VALVE HIGH- _hTv, l REGULATOR NITROGEN PRESSURE ,__ _ .)
/- RESERVOIR
........... r DIFFERENTIAL l
TEMPERATURE AND _r LU"IKUL I PRESSURE i I PRESSURE SENSORS V.L._ 7 I SENSOR--'-. I TO ENGINE FILLER _ _ [] _ _ _--'_'[_--_'ACCELERATOR T I | FLOWMETERS dG'r_ _l'i'! l _ AREA TO ENGINE I ......... / / INJECTION RU/Un_/I_ / CONTROL SAFETY // _T_ HARDWARE SHUTOFF VALVE-*" TEMPERATURE SENSOR FIG. 3 SCHEMATIC OF WATER INJECTION SUPPLY SYSTEM.
OPTICAL PYROMETER LEAD (_ IGNAL WAER OUTLET WATER PHOTODI ODE _ JACKET SPIRAL COOLING QUARTZ ./.
CHANNEL WATER --WATER INJECTION LENSFAcE---_OF _" _/ INLET SUPPLY TUBE PYROMETER// BODY I- FIRST-STAGE I TURBINE ROTOR / COMBUSTOR -- / / FIRST-STAGE NOZZLE -- / \ L WATER x_ COOLING AIR DISTRIBUTION ACCELERATOR RING FIG. h LOCATION OF PYROMETER IN ENGINE HOT SECTION.
The upper limit of water addition was to be determined by for 30 rain without loss of hot-section life. Data were obtained at several water-flow rates to validate the measuring plotting the temperature of the mixture against the water/ cooling air ratio (Fig. 5). The point at which the water had system and the predictions of metal temperature versus water- little additional effect was anticipated to be shown by a cor- flow rate before testing above IRP was begun.
responding change in slope on the aforementioned curve. The cooling effectiveness of the water addition was of significance The objective of the engine test was to increase the maximum at least to a water/cooling air ratio of 13 percent, the limit of power output by raising the turbine inlet temperature while the test rig.
keeping the bulk temperature of the first-stage turbine rotor blades within limits.
The model tests were conducted with either 5 holes or 15 holes in the distribution ring. No significant transient or The test procedure followed a conservative approach. A steady-state differences were noted between these two config- "derated" part-power base setting was selected where no water urations. The 5-hole configuration was chosen for the engine was injected. Measurements were then systematically made tests because it resulted in a higher pressure differential in the at increasing power levels while injecting water. By taking supply system and thus allowed greater control of the water.
faidy small increments in temperature, the engineers could observe any unpredicted trends should they occur. Each water-flow rate was held for 1 to 2 rain. Hot-section tern- Engine Tests perature limits were established and adhered to as the test progressed. The engine test results include a visual inspection report that was compiled after testing had been completed and a detailed discussion of the engine data. The test results show the bene- The baseline data from which exploration at temperatures t-as of water injection into the turbine cooling air and include above IRP was conducted, the guidelines used from a comparison of engine data with both the model test data and Hirschkron (Ref. 5), and our experimental observations are the predicted results from the conceptual design study discussed in the following statements: (Ref. 5).
(1) Temperature data from the thermocouples described in the section "Engine Instrumentation" were recorded. These Overall Engine Condition data were extrapolated and used as a guide during the subse- A borescope inspection showed no visual signs of hot-section quent exploration to higher turbine inlet temperatures.
distress. No engine hot-section disassembly was performed, nor was it required. Operational limits regarding gas genera- (2) Significant deviations of test data from predicted tor and power output shaft speeds and temperature were never values would warrant further investigation and corrective exceeded so as to retain as much turbine blade life as possible.
action, including inspection of hot-section hardware. No This restriction was also imposed because the engine is a test significant deviations were seen during the engine testing.
bed intended for future research work.
(3) A number of routine inspections of hot-section hard- This is not to insinuate that no risk was involved in the pro- ware would be performed to establish a correlation between gram. Quite the opposite was true. For the maximum power the hot-section condition and the temperature levels above the situations the engine electronic control unit (ECU) was locked established baseline. A new baseline would be established out. The engine operator was thus required to monitor and each time a hot-section inspection was conducted. No abnor- limit rotor speed and turbine temperature. Because of the con- malities were seen during the inspections.
figuration of the facility power absorber controls, and since the engine ECU was locked out, the power absorber command (4) The blade leading-edge temperatures would be meas- signal required manual biasing (by a second operator) to con- ured with the optical pyrometer.
trol engine power output speed and to reach the higher power levels. The addition of water injection required a third RESULTS AND DISCUSSION operator who affected the operating level of the engine. Con- sidering these test variables, a key factor in the success- The results of model tests with the water injection system are ful completion of the testing was the support personnel's presented, as well as the results of the engine tests. The expertise.
model results affected the choiee of injection configuration for the engine and were used to calibrate the cooling system.
No atypical vibrations were observed during the testing, nor was a compressor stall indicated. The system used for stall detection was proven to be reliable in previous engine tests.
Model Tests The pyrometer performed flawlessly for the duration of the The model tests were conducted to determine the water flow tests, approximately 26 hr, and fulfilled its intended purpose that could be effectively added to the turbine cooling airflow as the primary data source.
of the full-scale turboshaft engine. This information was obtained as well as information on the mass flow function for Transient System Response the turbine cooling air system accelerator. This was also an opportunity to gain operational experience with the water sup- A consideration during the design and planning stage of the ply system before its use with the engine. program was the state of the water/steam passing through the injection system. Too much water downstream of the turbine The throttle push was done and Fig. 9 shows the results for cooling air accelerator (Fig. 4) could conceivably result in engine operation at or near IRP where contingency power is "flooding" and sudden cooling of such components as seals.
normally applicable. These data were obtained by increasing With too little water the fast-stage turbine blades would not the rotor speed after water addition until it was approximately be cooled enough to allow for higher turbine inlet tempera- equal to the speed before water addition. The result was a tures as fuel was added. A maldistribution of the coolant turbine blade leading-edge temperature that was approximately might lead to temperature nonuniformities in the seals down- the same with and without water injection but a higher power stream of the accelerator and eventual turbine distress. The output with water injection.
time to charge the system, or the time to reach a steady-state condition, before the turbine temperature could be increased The power increase was approximately 3 to 5 percent for a was also a consideration.
6- to 7-percent water addition. This allowed a corresponding turbine rotor inlet temperature increase of about 60 deg F.
The concerns about control of the engine and the water injec- This result agreed with the rate of power increase estimated in tion system if flooding, insufficient cooling, and maldistri- the conceptual design study. If the restraints previously men- bution of flow occurred were minimized mainly by the test tioned for this test-bed engine did not exist and it were pos- techniques employed and the hardware developed for the pro- sible to raise the turbine rotor inlet temperature by 300 deg F granl. Regarding the transient response of the system, for a as was done in the conceptual design study, a 17-percent typical water/cooling air ratio of approximately 6 percent, increase in power could be realized.
approximately 5 see elapsed from the time water flow was initiated until a change in temperature was observed. This The model data (Fig. 5) show the potential for cooling effec- occurred at a thermocouple measuring a temperature near the tiveness to at least a 13-percent water/cooling air ratio. How- water distribution ring. Furthermore, a significant drop in ever, data were not gathered at IRP, or above, beyond a 6- to temperature did not occur until about 3 sec later. It should be 7-percent water/cooling air ratio (Fig. 8) because there was noted that the time differential between water addition and concern about possible thermal shock and seal distortion near temperature drop must be taken into account in an operational the humid-air mixing station. Therrnocouple readings of the system. The thermocouples downstream of the accelerator, humid air downstream of the accelerator did show a tempera- where the air/steam mixture should be most completely mixed, ture maldistribution that increased with increasing water/ showed a greater delay.
cooling air ratio. One explanation for the maldistribution is that it could be a configuration-dependent mixing problem (i.e., type of distribution ring, number of holes in the ring, Steady-State Results engine configuration, etc.).
Water was added to the turbine cooling air as described in the section "Water Injection System." With water addition the Com_son of Engine and Model ResuRs rotor speed (Fig. 6) decreased as did the power output (Fig. 7). These figures show that adding water in itself did Engine and model test results disagreed in predicting the not necessarily result in a net gain in engine performance. In water/cooling air ratio beyond which this configuration would fact, just the opposite effect is revealed in these parameters. show no increase in cooling capacity. This can be seen by comparing Figs. 5 and 8, which show marked differences in The Ioss in speed and, in turn, the loss in power were antici- slope (or decreases in temperature) at the various water/ pated during the conceptual design study. Turbine cooling air- cooling air ratios. This lends credence to the argument that flow is greater with water injection because the cooling air the engine data are limited in water/cooling air ratio effective- becomes denseras water-Is added_ Thus, more compressor air ness by configuration constraints rather than saturation conditions.
is diverted for turbine cooling, and less air is available to drive the turbine than with dry turbine cooling air. The result is a decrease in rotor speed. Another consideration was that Comparison of Engine and Conceptual Design Results the cooler turbine blades become shorter, thus increasing the tip clearance and causing a drop in turbine efficiency (Ref. 5).
Comparing first-stage, turbine blade, leading-edge tempera- Hirschkron (Refs. 5 and 6) addresses other effects on the tures from the engine test results and the conceptual design engine and components with water_jectlon, but insufficient study was difficult because the engine test was run at varying instrumentation was available in the test-bed engine to verify turbine inlet temperatures while the study was performed at his analytical work. A significant result of these studies was a constant turbine inlet temperature. An attempt was made that turbine life was estimated tobe over 30 times shorter (Fig. 10) to compare the test and study results by using a without water injection than with it at a turbine inlet gas dimensionless temperature parameter. This parameter con- temperature 300 deg F above IRP.
rained key temperatures, such as turbine inlet temperature, coolant temperature, and turbine blade leading-edge tempera-
i
The speed decrease would be only one consequence of water ture. The equation is T* = (T M - TC)/(T G - Tc) where T C injection if this were an operational system. The additional is the coolant temperature downstream of the accelerator, T G heat sink available in the turbine cooling air because of the is the calculated turbine-rotor:inlet gas temperature, and T M water's latent heat of vaporization did lower the first-stage, is the first-stage, turbine blade, leading-edge temperature.
turbine blade, leading-edge temperature (Fig. 8) even as rotor speed and power decrease_d. The watei addition permitted Cons;dering the limited amount of data available and the operation at a higher turbine rotor inlet temperature, as would limited range of conditions covered during engine tests, the be accomplished in a real-wodd contingency power situation results are reasonable. The disagreement can be explained by by a throttle push or a fuel increase.
800 -- 250 -- 700 ( _ 200 60O i 100 0 BASE TEMPERATURE D BASE + 135 DEG F & IRP 300 _ 0(i_ I
I
200 I I I I I I I -_ !
o 2 4 G 8 ;o _2 1_ 2 4 G 8 _o
WATER/COOLING AIR RATIO, PERCENT + WATER/COOLING AIR RATIO, PERCENT FIG. 5.- EFFECT OF WATER/COOLING AIR RATIO ON HUMID- FIG, 8 EFFECT OF WATER/COOLING AIR RATIO ON FIRST- AIR TEMPERATURE DOWNSTREAM'OF ACCELERATOR. FIVE-HOLE STAGE, TURBINE BLADE, LEADING-EDGE TEMPERATURE, DISTRIBUTION RING: AIRFLOW RATE, O.4G LB/SEC.
5 -- WATER/ COOLING AIR RATIO, _ PERCENT / _ -- 4 POWER , 3 -- _ G_7 / / _ 3 -- _ []0 LESSTHAN IRP1RP 1 , N
I
o 50 100 150 200 250 300 350 400 0 2 _ G TURBINE INLET GAS TEMPERATURE CHANGE, DEG F WATER/COOLING AIR RATIO, PERCENT FIG. 6 EFFECT OF WATER ADDITION ON ROTOR SPEED AND FIG. 9 EFFECT OF WATER/COOLING TURBINE INLET TEMPERATURE (CHANGE FROM BASE CONDITION). AIR RATIO ON POWER OUTPUT WITH FIRST-STAGE, TURBINE BLADE, 4OF-- WATER/ LEADING-EDGE TEMPERATURE COOLING AIR CONSTANT.
RATIO, 55 PERCENT /"[] 30 [] 6-7 • 25 20 "+ .85 -- [] BASE + 100 DEG F _ BASE * 135 DEG F I 0 REF. 5 15 _ _+ 0 0 IRP
V/r I I I I I I I I i .Ts I , I I J
0 50 100 150 200 250 300 350 400 0 q 8 12 16 TURBINE INLET GAS TEMPERATURE CHANGE, DEG F WATER/COOLING AIR RATIO, PERCENT FIG. 7 EFFECT OF WATER ADDITION ON POWER OUTPUT AND FIG. 10 EFFECT OF WATER/C_OLING AIR RATIO ON DIMEN- TURBINE INLET TEMPERATURE (CHANGE FROM BASE CONDITION).
SIONLESS TEMPERATURE. T = (TM - TC)/(TG - TC).
the lack of instrumentation for accurately determining the 2. Van Fossen, G.J., _The Feasibility of Water Injection Into mixed air/steam temperature downstream of the accelerator the Turbine Coolant to Permit Gas Turbine Contingency due to space restrictions.
Power for Helicopter Application," ASME Trw_sactions, JourTtal of EIzg#teering for Power, Vol. 105, No. 3, July 1983, pp. 635-642.
CONCLUDING REMARKS 3.
Richards, D.R. and Florschuetz, L.W., "Forced Convection An experimental investigation was conducted into the feasibil- Heat Transfer to Air/Water Vapor Mixtures," NASA ity of supplementing turbine cooling air through water injec- CR-3769, 1984.
tion. The results of this investigation led to the following observations: 4.
Janseen, J.M., Florschuetz, L.W., and Fiszdon, J.P., "Heat Transfer to Two-Phase Air/Water Mixtures Flowing (1) A unique system for injecting and evaporating water in Small Tubes With Inlet Disequilibrium," NASA into the turbine cooling air was successfully designed, fabri- cated, installed, and tested in a small turbine engine. CR-175076, 1986.
.
(2) The results of the tests demonstrated the potential for Hirschkron, R., Manning, R.F., and Haynes, J.F., "Contin- gency Power Study," R81AEG045, General Electric Co., increases in power of 17 percent corresponding to increases in Lynn, MA, Oct. 1981.
turbine inlet temperature of 300 deg F, while maintaining con- stant turbine rotor blade temperature.
6.
Hirschkron, R., H_iynes, J.F., Goldstein, D.N., and Davis, R.H., "Rotorcraft Contingency Power Study," (3) Concem for unprotected subcomponents in the hot NASA CR-174675, 1984.
section prevented demonstration of the technlque's higher potential.
7. Lewis, W.J., "WSTOL Engine Devdopment," AIAA Paper 84--1337, 1984.
(4) Further development of this unique system is required to optimize its potential for contingency power.
REFERENCES 1. Dugas, R.E., "Gas Turbine Engine Power Augmentation and Emergency Rating," USAAVLABS TR-68-12, Gen- eral Electric Co., Lynn, MA, 1968.
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1. AGENCY USE ONLY (Leave I)lan(( i ..... 2. REPORT DATE 3. REPORT TYPE AND DATES COVERED 1992 Technical Memorandum 4. TITLE AND SUBTITLE 5. FUNDING NUMBERS Contingency Power for a Small Turboshaft Engine by Using Water Injection Into Turbine Cooling Air WU-505-68-32 6. AUTHOR(S) Thomas J. Biesiadny and Gary A. Klann ,i 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) 8. PERFORMING ORGANIZATION REPORT NUMBER NASA Lewis Research Center Cleveland, Ohio 44135-3191 and E-7058 Propulsion Directorate U.S. Army Aviation Systems Command Cleveland, Ohio 44135-3191 10. SPONSORING/MONITORING 9. sPONSORING/MONITORING AGENCY NAMES(S) AND ADDRESS(ES) AGENCY REPORT NUMBER National Aeronautics and Space Administration Washington, D.C. 20546-0001 NASA TM-105680 and AVSCOM TR-92-C-019 U.S. Army Aviation Systems Command St. Louis, Mo. 63120-1798 11. SUPPI'EMENTARY NOTES Prepared for the 80th Symposium on tlcat Transfer and Cooling in Gas Turbines sponsored by the AGARD Propulsion und Encrgctics Panel, Antalya, Turkey, October 12-16, 1992. Thomas J. Bicsiadny, NASA Lewis Research Center, and Gary A. Kkmn, Propulsion Directorate, U.S. Army Aviation Systems Command. Responsible person, Thomas J. Bicsiadny, (216) 433-3967.
12a. DIsTRIBUTION/AVAILABILITY STATEMENT 12b. DISTRIBUTION CODE Unclassified-Unlimited Subject Category 07 13. ABSTRACT (Maximum 200 words) Because of one-engine-inoperative (OEI) requirements, together with hot-gas reingestion and hot-day, high-altitude take- off situations, power augmentation for multiengine rotorcraft has always been of critical interest. However, power aug- mentation by using overtemperature at the turbine inlet will shorten turbine life unless a method of limiting thermal and mechanical stresses is found, A possible solution involves allowing the turbine inlet temperature to rise to augment power while injecting water into the turbine cooling air to limit hot-section metal temperatures. An experimental water injection device was installed in an engine and successfully tested. Although concern for unprotected subcomponents in the engine hot section prevented demonstration of the technique's maximum potential, it was still possible to demonstrate increases in power while maintaining nearly constant turbine rotor blade temperature.
15. NUMBER OF PAGES 14. SUBJECT TERMS Engine tests; Contingency; Horsepower; Turboshafts; Augmentation; Engine 16. PRICE CODE failure; Helicopters A02 20. LIMITATION OF ABS"I_RACT 19. SECURITY CLASSIFICATION 18. SECURITY CLASSIFICATION 17. SECURITY CLASSIFICATION OF ABSTRACT OF REPORT OF THIS PAGE Unclassified Unclassified Unclassified Standard Form 298 (Rev. 2-89) NSN 7540-01-2130-5500 Prescribed by ANSI Std. Z39-1B 298 102