Research on thermal adjustment method of RBCC in ramjet mode

In order to further enhance the performance of RBCC engine in ramjet mode, one-dimensional analysis model was used to study the methods of thermal adjustment based on the matching operation between combustor and isolator. The results show that the main influencing factors of thermal throat in the expanding duct of RBCC were expansion ratio, exothermic quantity, exothermic rate and injection position. The bigger of expansion ratio, the less of exothermic quantity, the faster of heat release or the more front of injection location is, the earlier thermal throat forms in duct. Through the variation of above parameters in certain range, thermal throat position changes by 9%~22%. The more after of thermal throat position is, the bigger of integral thrust can be obtained when the expansion ratio of combustor and total exothermic quantity are the same. Compared to the expansion ratio and exothermic rate, changing the position of fuel injection is an effective and easy method to implement the thermal adjustment. More after of combustion organization should match the larger expansion angle of duct, which can effectively extend the range of thermal adjustment and the margin of engine operation. In the study of performance optimization, compared to the fixed position of injection, the thrust of engine can achieve 16.5%~24.1% improvements at fly condition of Ma=3~5 by using the thermal adjustment method of changing fuel injection location.