120 kHz mid-infrared TDLAS sensor for H2O concentration and temperature measurement in rotating detonation engine exhaust flows

Abstract

Rotating detonation engines (RDEs) require advanced rapid combustion diagnostic techniques to better understand their complex detonation processes. A fast mid-infrared TDLAS sensor was proposed to simultaneously monitor H2O concentration and temperature at the outlet of an H2/air-fueled RDE annular combustor. An iterative parameter extraction method from transmitted laser intensity was proposed to extract the H2O concentration and temperature of the detonation waves. A measurement rate of 120 kHz enables high-speed and simultaneous quantification of detonation wave combustions. The results show that when RDE operates stably, the detonation frequency, average temperature, and average molar percentage of H2O concentration of the detonation waves are 4.631 kHz, 1572.8 K, and 0.335, respectively. The detonation frequency extracted from H2O concentration and temperature is highly consistent with that extracted from thermal radiation, and the relative frequency error is only 0.022 %. The time-resolved H2O concentration and temperature data measured by the sensor accurately capture the thermal dynamics of the transient detonation waves.