Wave-Rotor-Enhanced Gas Turbine Engines

Abstract

The benefits of wave rotor-topping in small (400 to 600 hp-class) and intermediate (3000 to 4000 hp-class) turboshaft engines, and large (80,000 to 100,000 lb, class) high bypass ratio turbofan engines are evaluated. Wave rotor performance levels are calculated using a one-dimensional design/analysis code. Baseline and wave rotor-enhanced engine performance levels are obtained from a cycle deck in which the wave rotor is represented as a burner with pressure gain. Wave rotor-topping is shown to significantly enhance the specific fuel consumption and specific power of small and intermediate size turboshaft engines. The specific fuel consumption of the wave rotor-enhanced large turbofan engine can be reduced while operating at significantly reduced turbine inlet temperature. The wave rotor-enhanced engine is shown to behave offdesign like a conventional engine. Discussion concerning the impact of the wave rotor/gas turbine engine integration identifies tenable technical challenges.

Experimental Results of Performance Tests on a Four-Port Wave Rotor

“…The performance increases rapidly at first as the mass flow is reduced from the maximum possible, then tails off after the flow rate reaches 0.67 lb/s. The lowest value of 2 m used provides a lower performance. Lines of the pressure drop in the high pressure loop, i.e., (P 2 -P 3 )/P 2 are also plotted in figure 11.…”

“…14). The latter is given approximately by: (2) and is typically small compared with the pressure drop due to the pressure loss factor. Running the experiment at constant k loss would therefore correspond roughly to a real wave rotor.…”

“…The pressure drop increases rapidly as m 2 decreases. It might be thought that a low drop is desired, but the situation is more complicated-to obtain a high value of 2 m , a low pressure drop is required, so that the high pressure loop must have a low value of k loss . In figure 12, λ (closed symbols) and (P 2 -P 3 )/P 2 (open circles) are plotted against k loss .…”

Performance Investigation of Small Gas Turbine Engines Topped with Wave Rotors

“…In 1995, Welch et al 20 have predicted a 19…21% increase in specific power and a 16...17% decrease in specific fuel consumption compared with the baseline engines in performance calculations for small (300 to 500 kW) and intermediate (2000 to 3000 kW) waverotor-enhanced turboshaft engines. Same calculations for a wave-rotor-enhanced large turbofan engine, equal in thrust to the baseline engine, have shown a 6…7% reduction in thrust specific fuel consumption.…”

“…Since the 1990s, a large research program at NASA Glenn Research Center (GRC) collaborated by the U.S. Army Research Laboratory (ARL) and RollsRoyce Allison has initiated to develop and demonstrate the benefits of the wave rotor technology, which will be useful in future aircraft propulsion designs. [9][10][11][12][13][14][15][16] An excellent overview has been provided by Welch. 17 In 1993, using a thermodynamic approach to calculate the thermal efficiency and specific power, Wilson and Paxson 18 published a feasibility study for topping jet engines with a wave rotor.…”