Numerical Simulation of the Ram Combustor for High-Mach Integrated Control Experiment (HIMICO)

Abstract

Japan Aerospace Exploration Agency (JAXA) has planned High-Mach Integrated Control Experiment (HIMICO), which is a flight experiment under hypersonic conditions. The ramjet engine used in the experimental aircraft is designed for self-ignition of the fuel to occur due to high temperature caused by aerodynamic heating in hypersonic flow. We confirmed that self-ignition occurred under some test conditions in the combustion test. However, conditions of the incoming air and the injected fuel where self-ignition occurred were not clear. In this study, we develop a chemically reacting flow solver for investigating the self-ignition. Large-eddy simulations of the combustor of the HIMICO engine are performed using a detailed hydrogen-air reaction mechanism. The results show that qualitative prediction whether self-ignition occurs is possible by Large-eddy simulations using the solver. In the simulations, self-ignition occurs even under conditions where self-ignition did not occur in the test. On the other hand, it is found that the selection of the boundary condition of the injector outer walls has a great effect on the time to self-ignition. For improving the accuracy of prediction, it is necessary to consider turbulence and three-dimensional flow due to the intake and the effects of heat exchange on the injector outer walls.