Scramjet Combustion Efficiency Measurement via Tomographic Absorption Spectroscopy and Particle Image Velocimetry

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 one-dimensional control volume calculation or a calorimeter and wall pressure tap measurements. A novel nonintrusive direct approach for the measurement of combustion efficiency is presented that combines the optical diagnostic techniques tunable diode laser absorption tomography and stereoscopic particle image velocimetry. Experimental results are presented for measurements of the University of Virginia’s Supersonic Combustion Facility in both the scram and ram-modes of operation. The tunable-diode-laser-absorption-tomography/stereoscopic-particle-image-velocimetry method directly measures the converted hydrogen (via water vapor) mass flow rate exiting the dual-mode scramjet and compares this to the facility-measured injected hydrogen fuel mass flow rate. A complementary computational fluid dynamics study was perfo...