Direct Measurement of Combustion Efficiency of a Dual-Mode Scramjet via TDLAT and SPIV (Invited)

Abstract

The combustion efficiency of a scramjet is a metric that evaluates the overall performance of the engine. Until recently, combustion efficiency was measured using indirect approaches such as a 1-D control volume calculation or calorimeter and wall pressure tap measurements. A non-intrusive direct approach for the measurement of combustion efficiency is presented which combines the optical diagnostic techniques tunable diode laser absorption tomography (TDLAT) and stereoscopic particle image velocimetry (SPIV). Experimental results are presented for measurements on the University of Virginia’s supersonic combustion facility (UVaSCF) in both the scramand ram-modes of operation. The TDLAT/SPIV method directly measures the flux of water vapor exiting the dual-mode scramjet and compares this to the facility-measured injected H2 fuel flux. A complementary computational fluid dynamics (CFD) study was performed and results were available for only the scram-mode operating condition. The results reported show excellent agreement between the TDLAT/SPIV measured combustion efficiency and the CFD predicted combustion efficiency for the scram-mode of operation, both near 99%. The TDLAT/SPIV measured combustion efficiency for the ram-mode of operation is shown to be lower than that of the scram-mode operation, at 79%.