Simulation And Experimental Research On The Configuration Of Combustor In Scramjet

The influence of the divergence angle of the combustor shape, cavity locations and the fuel distribution to the performance of the multi-cavity combustor in Scramjet was studied by both experiment and numerical simulation methods.The combustion performance of the multi-cavity combustor with liquid kerosene fuel on room temperature was investigated experimentally, with different divergence angles of the combustor shape, different cavity locations and fuel distribution. Results indicate that in the combustors with the same cavity locations and fuel distribution, the extent of thermally choke is determined by the the expansion angles. In the condition that the ratio of the combustor exit area to the inlet area is constant, the combustor with constant-area isolator and other parts expanding gradually has the highest thrust increment. The thrust increment is determined both by the static pressure in combustor and by the divergence angle of the shape. So, thrust increment doesn't vary in proportion with the static pressure. The influence of cavity locations and fuel distribution to the combustor changes with different expansion angles of the combustor, and proper circumferential fuel injection distribution helps to enhance the combustor performance.A reasonable mathematic model about the physical phenomenon in the combustor was given to simulate the combustion and flow process in the combustors. Four real-size combustors which have the same cavities located on the up and down walls and have different divergence angles were studied. Another combustor with cavities located on the side walls was studied too. The results, which were proved to be identical with the experimental data, indicate that, the divergence angle of the combustor shape, the cavity locations and fuel distribution are crucial factors to the flow process in the combustor. The combustor is thermally choked either intensely or weakly, and the most important difference between them is that core-flow is always supersonic in the combustor and there is no pre-combustion shock train in the isolator when it's choked weakly. The flow field in the cavities is greatly influenced by the divergence angles, and they both affect the combustor performance. There is not a sample rule among thrust, combustion efficiency and the ratio of total pressure at outlet to that at inlet, and no combustor can act best on every aspect of performance. So a compromising method is needed to evaluate the combustor performance.