Test performance evaluation of rocket based combined cycle engine using TDLAS technique

For the wide operating range, the performance evaluation of rocket based combined cycle (RBCC) engine, such as thrust, specific impulse and combustion efficiency, is difficult to directly calculate by key parameters in-situ and online measurements. In this paper, a non-intrusive laser spectroscopy method based on tunable diode laser absorption spectroscopy (TDLAS) is proposed to measure the temperature, species concentration and velocity of burned gas simultaneously. The time-division multiplexing-wavelength scanning TDLAS system is designed to obtain the spectrums near (7444.352+7444.371)/7185.597 cm^-1 of exhaust gas in RBCC ground test. And the gas temperature, H₂O species concentration, and velocity parameters are determined. With the longitudinal distributions of parameters which obtained by numerical method, the thrust, specific impulse and combustion efficiency of RBCC ground test can be directly caculated by the TDLAS measurements. It can provide a reference for the optimization of combustion organization and engine structure.