Effect of combustion mode on thrust performance in a symmetrical tandem-cavity scramjet combustor

Abstract

To investigate the relationship between the thrust performance and combustion mode in a scramjet combustor, the acceleration process of a symmetrical tandem-cavity combustor is numerically investigated based on previous experiments. The numerical results are essentially in agreement with the experimental results through high-speed photography and wall pressure comparisons, which verifies the reliability of the numerical method. Then, three groups of simulations with different equivalent ratios are designed under the condition of inlet flow Mach numbers 2.4, 2.5, 2.6, 2.7, and 2.9. Complete combustion efficiency and specific section thrust are defined to measure the combustion efficiency of kerosene and thrust performance. Four combustion modes are defined and observed in simulations, i.e. strong ram mode, weak ram mode, dual-mode ram mode, and scram mode. The simulation results show that the combustion modes in the former and the later cavities for this tandem-cavity scramjet combustor are related to each other. Combustion modes have a significant impact on the thrust performance of the combustor and the specific section thrust mutation is caused by mode transition. Under different inlet Mach numbers, appropriate equivalent ratio settings can improve thrust performance for this tandem-cavity supersonic combustor. Two ideal combustion modes realized by different injection schemes are proposed for better thrust performance of symmetrical tandem-cavity supersonic combustor.