The Characteristics Of The Cavity Flame Holders In The Dual-Mode Scramjet Combustor With Hydrocarbon Fuel

The dual-mode scramjet can apply to the wide range of the flight Mach number from the supersonic to hypersonic. For the some new conceptions, the cavity integrated fuel injector, mixer and flame holder is more potential to improve the performance and acquire the maximal thrust of the dual-mode scramjet. In the thesis, the characteristics of the cavity flame holder and mode transition of the liquid kerosene combustion in the dual-mode scramjet combustor are studied experimentally and numerically in detail.1. Experiment testThe two cavity flame holders were designed for the dual-mode scramjet combustor model, that is to say, one was a normal cavity and the other was a beveled cavity. At the different flight Mach, the investigation of liquid fuel kerosene was carried out in the combustor direct-connect wind tunnel. With one-dimensional analysis method, the flow field parameters, the total pressure loss coefficient and combustion efficiency were estimated in terms of the measured wall static pressure data. For the dual-mode ramjet/scramjet research, the mode transition is one of the key techniques. At the flight Mach 5 and three fuel-air equivalent ratios, namely, 0.386,0.48 and 0.551, liquid fuel kerosene realizes ignition and stable combustion. The combustion mode transits from supersonic combustion to subsonic combustion as the equivalent ratio of fuel-air decreases from 0.551 to 0.386. The cavities integrated fuel injector, mixer and flame holder can improve mix and combustion of the liquid kerosene and air, and the combustion efficiency.2. Numerical SimulationThe test dual-mode scramjet combustor was analyzed and simplified in order to establish the appropriate mathematical model. By comparison simulation results and the experimental data, the models used in the numerical simulation and the simulation results are valid and correct.In the case, which flight mach number was 5 and the fuel-air equivalence ratio was 0.551, the numerical results were gotten with the eddy-dissipation model and presumed probability density function (PDF) model to describe the interaction of turbulence and combustion. The PDF model combined with mixture-fraction...