Experimental research on the thermal throat of rocket based combined cycle combustor

Based on a previous one-dimensional theoretical analysis, direct-connection experiments of thermal throat generation and the factors that influence it in the Rocket Based Combined Cycle combustor are performed relative to the fuel injection position and equivalence ratio. The Mach 5.5 airflow experimental results indicate that the performance is improved by 3.0–8.3% by optimizing the fuel injection position, and at an airflow of Mach 4.0, the increase in the fuel equivalence ratio gradually shifts the generation of the thermal throat backward. When a thermal throat is generated at the end of the combustor, the thrust and specific impulse performance are optimal. The effectiveness of employing a thermal adjustment to improve engine performance is validated by the experimental studies. The radiation spectrum method is employed to measure the temperature along the flow field of the thermal throat. The temperature and pressure measurements along the flow path indicate that the Mach number variation trend calculated in the experiment is the same as that observed in the numerical simulation results in the thermal throat flow field. The generation process of the thermal throat is characterized by the acceleration of airflow from being subsonic to supersonic.