Experimental investigation on combustion efficiency of the ramjet model at low pressure

On the direct-connect high altitude experiment system, the ramjet models were successfully ignited and combusted stably at the pressure between 40 kPa and 60 kPa. According to these tests, the influence parameters on combustion efficiency were studied under variable conditions, including the combustor configuration, the inflow condition at the entrance of the combustor and the equivalent ratio. Results show that the combustion efficiency at the low pressure is lower than that at the normal and high pressure, but the variation trend is almost the same. The increase of the length of the combustor, the total temperature, the total pressure, and the equivalent ratio, the decrease of the flight altitude, and the enhancement of atomization and mixing can increase the combustion efficiency. However, the decrease of the ratio of length-to-depth can improve the combustion efficiency.