The combustion efficiency of supersonic hydrogen-air flames

Combustion efficiency was measured for a supersonic, non-premixed, jet-like flame, The flame was stabilized along the axis of a Mach 2.5 wind tunnel and wedges were mounted on the sidewalls in order to produce oblique shocks that interacted with the flame. Efficiency was measured using a solid state hydrogen gas detector that analyzed exit flue gas. It was observed that moving the wedges to different downstream locations affected the visible flame length, but had no impact on the combustion efficiency, This was observed over a range of fuel mass flow rates, The oblique shocks produced about a 8% reduction in combustion efficiency regardless of wedge position, although there was some variation in reduction depending on the fuel flow rate, The shock waves cause radial inflow and outflow that allows some of the fuel to escape unburned.