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Wave Rotor Research and Technology Development
Wave rotor technology offers the potential to increase the performance
of gas turbine engines significantly, within the constraints imposed
by current material temperature limits. The wave rotor research
at the NASA Lewis Research Center is a three-element effort:
- Development of design and analysis tools to accurately predict
the performance of wave rotor components
- Experiments to characterize
- System integration studies to evaluate
the effect of wave rotor topping on the gas turbine engine system
In the last year, significant progress was made in the dynamic
simulation of wave rotors and gas turbine engines. The figure
shows the response of wave-rotor-topped and baseline gas turbine
engines to a step change in fuel flow: the wave-rotor-topped engine
is more stable with respect to burner-induced surge (ref. 1).
Progress was also made in advanced component research:
passage flow area variation was found to improve aerodynamic performance
- A new gas dynamic wave cycle was developed that
greatly alleviates the thermal loading of the wave rotor and its
ducting (ref. 3).
- Gas dynamic wave cycles and fuel/air premixing
schemes were developed for wave rotors with combustion internal
to the wave rotor (this approach conceptually eliminates the conventional
burner of the gas turbine engine while still providing the engine-performance
benefits afforded by wave rotor topping (ref. 4)).
- A preliminary
assessment of wave turbines (i.e., wave rotors that produce net
shaft power) revealed that wave turbine topping potentially enhances
engine specific power more than the classical pressure-exchanger
(i.e., zero-net-shaft-power wave rotor) topping does (ref. 5)
Comparison of the dynamic responses of wave-rotor-topped
and untopped gas turbine engines to step changes in fuel flow.
Progress has continued on the four-port pressure-exchanger experiment,
which is designed to demonstrate startup, self-cooling effectiveness,
and passive end-wall-leakage control, and to generate on- and
off-design wave rotor performance data (i.e., a wave rotor map).
The experiment uses an electric heater to add energy to the wave
cycle in place of the burner component of the gas turbine engine.
The experiment will operate at lower temperatures and pressures
than would a wave rotor in an engine; however, all pressure and
temperature ratios will be reproduced without the complications
of variable gas properties (ref. 6).
A collaborative effort with the Allison Engine Company has yielded
a preliminary design layout for a potential wave-rotor-enhanced
demonstrator based on the Allison 250 turboshaft engine (ref.
7). Significant findings from this contracted effort include the
- With existing Allison 250 engine turbomachinery
hardware, wave rotor topping increases specific power by 20 percent
and concomitantly decreases specific fuel consumption by 22 percent
at full power.
- Improvements in specific power are maintained
at part-power operation.
- The surge margin of the topped engine
is equivalent to that of the production engine.
- The wave
rotor maintains high off-design performance.
- Greendyke, R.B.; Paxson, D.E.; and Schobeiri, M.T.: Dynamic
Simulation of a Wave Rotor Topped Turboshaft Engine. AIAA Paper
97-3143 (NASA TM-107514), 1997. Available online.
- Paxson, D.E.; and Lindau, J.W.: Numerical Assessment of Four-Port
Through-Flow Wave Rotor Cycles With Passage Height Variation.
AIAA Paper 97-3142 (NASA TM-107490), 1997. Available online.
- Paxson, D.E.; and Nalim, M.R.: A Modified Through-Flow Wave
Rotor Cycle With Combustor Bypass Ducts. AIAA Paper 97-3140, 1997.
- Nalim, M.R.; and Paxson, D.E.: Numerical Study of Stratified
Charge Combustion in Wave Rotors. AIAA Paper 97-3141 (NASA TM-107513),
1997. Available online.
- Welch, G.E.: Wave Engine Topping Cycle Assessment. AIAA Paper
97-0707 (NASA TM-107371), 1997.
- Wilson, J.: Design of NASA Lewis 4-Port Wave Rotor Experiment.
AIAA Paper 97-3139 (NASA CR-202351), 1997. Available online.
- Snyder, P.H.; and Fish, R.E.: Assessment of a Wave Rotor Topped
Demonstrator Gas Turbine Engine Concept. ASME Paper 96-GT-41,
Lewis contacts: Dr. Gerard E. Welch, (216) 433-8003,
Jack Wilson, (216) 977-1204,
and Daniel E. Paxson, (216) 433-8334,
Author: Dr. Gerard E. Welch
Headquarters program office: OASTT
Programs/Projects: Propulsion Systems R&T, SGE,
gas turbine engines
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Last updated April 15, 1998, by
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