Supersonic combustion using catalytic wire at constant temperature in a cold supersonic flow field was investigated in a square duct with a backward-facing step. The free stream Mach number was of Mm=1.81. Hydrogen was injected transversely behind a backward-facing step into a cold air free stream. The heat release due to the catalytic combustion has no effect of the temperature of catalyst. It indicates that the reaction rate of the catalytic combustion observed in this study was determined by the consentration of H2 and/or O2 on the surface of the catalyst. The spatial distribution of heat release due to the catalytic combustion in supersonic turbulent mixing layer, that corresponds to the spatial distribution of consentration of H2 and or/O2 in local, was obtained. It was found that there exists the most suitable position for the supersonic combustion at the outer edge of mixing layer.
