Effect of coaxial injector parameters on LOX/methane engines: A numerical analysis

Abstract

The liquid oxygen/methane engine is a desirable power for reusable launch vehicle. It is generally believed that the efficiency of the liquid oxygen/methane engine is mainly influenced by the injection conditions of the thrust chamber. However, due to the complexity of combustion experiments, the exact influence of specific injectors on the combustion performance is difficult to acquire. By analyzing a typical sub-scale thrust chamber, this paper presents a three-dimensional numerical model to evaluate the effects of three major injector parameters, i.e. the thickness of liquid oxygen post, the number of injectors and the type of injectors, on liquid oxygen/methane engine combustion performance. The results of the simulation are consistent with existing experimental data in the chamber pressure, combustion stability, as well as wall heat flux. This paper's results have shown that the larger liquid oxygen post thickness and swirl coaxial injector can significantly reduce the heat flux while influence of the injector number is relatively small. Furthermore, the decrement of the liquid oxygen post thickness can improve the combustion efficiency. And the less injectors lead to the more stable combustion. The presented simulation model gives a reliable and cost-effective way to analyze specific injector parameters and provides new principles for future liquid oxygen/methane engine design.