Application of tunable diode laser absorption spectroscopy in mesoscale hypersonic flow field measurement

In the air-breathing engine test, the component concentration in the inlet flow field is a key parameter, but there is a lack of online methods to measure this parameter in real time. Tunable diode laser absorption spectroscopy (TDLAS) is a mature low-cost non-contact flow field measurement technology, but it is primarily utilized for small-scale laboratory applications. To measure the component in the mesoscale hypersonic flow field in real time, this paper conducted the engineering application research of TDLAS component measurement and achieved the TDLAS application in measuring the component and temperature in the mesoscale hypersonic flow field. We developed a multi-component detection system consisting of multiple lasers, collimating mirrors, and detectors, measured data is transmitted to the computer for processing and can realize uninterrupted long-term monitoring. Through on-site testing, it has been shown that the designed system solves the problem of long-distance optical path layout and signal transmission in vacuum environments. It can measure signals normally under testing conditions, reflecting the state changes of corresponding components in the TDLAS optical path in the vacuum chamber in the flow field.