A multi-channel tunable diode laser absorption spectroscopy(TDLAS) system was constructed to measure flow parameters in a direct-connected scramjet test facility fueled with ethylene.Two fibers coupled distributed feedback(DFB) lasers with narrow line width were used to probe two H2O absorption featuresby using direct absorption time-division-multiplexing(TDM) strategy at a 4 kHz scan rate.Flow parameters were measured,which included the distribution of temperature,water vapor concentration and velocity at the exit cross section of the combustor,the distribution of temperature and water vapor concentration in the cross section near the cavity.Combustion efficiency was obtained by using the water vapor partial pressure distribution and the wall static pressure.Mach number distribution was deduced from the temperature and velocity parameters distributions at the exit cross section of the combustor,and the distributions of temperature and water vapor concentration in the cross section near the cavity were used to analyze combustion characteristics in the combustor. 更多
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