Measurement of supersonic flow parameters using laser absorption spectroscopy

Based on the tunable diode laser absorption spectroscopy(TDLAS) technique, temperature, concentration, velocity and mass flux of the supersonic flows were measured in isolator of a direct-connected scramjet. Two H2O absorption transitions 7 185.597 cm-1 and 7 454.445 cm-1 were adopted by using direct-absorption and Time Division Multiplexing strategy. The measurement results show the static temperature is of 899 K and the H2O concentration is of 20.7% calculating from the absorption area. A cross-beam configuration with angles of 60 along the flows was used to measure the axial velocity. Combined with the pressure sensor on the wall and the measured velocity of 1 205 m/s, the mass flux of the flow is of 1 500.49 g/s with deviation of 5.23%. The TDLAS measured system can be used for in-situ measurements of multiple parameters of supersonic flows.