预燃室低频不稳定燃烧仿真研究

Simulation investigations of low frequency combustion instability of precombustion chamber

为弄清燃烧不稳定性激励机制,建立了氢氧预燃室低频燃烧稳定性分析数学模型,利用MATLAB/SIMULINK集成软件包搭建仿真平台,研究了与供应系统耦合的低频不稳定燃烧。结果表明:在各种不稳定激励因素中,氧的喷注压降对稳定性影响最为显著,当其值低于某一稳定边界时,出现极限环振荡,提高氧的喷注压降可以非常有效地抑制低频不稳定燃烧;当氧的喷注压降位于稳定边界附近时,混合比将对稳定性产生一定影响,降低混合比可以较好地抑制低频不稳定;氢的喷注压降对低频燃烧稳定性影响很小。

To reveal the mechanism of combustion instability, mathematic models for low frequency combustion stability analysis are developed. Then the low frequency combustion instability coupled with feed system is simulated by using MATLAB/SIMULINK software. The results show that the reduction of oxygen injection pressure is the most remarkable factor that prompts the instability. Once it is below a certain stable boundary, pressure oscillation increases to a limit cycle. So increasing the reduction of oxygen injection pressure can restrain the instability very effectively. If the reduction of oxygen injection pressure is close to the stable boundary, the oxidizer-fuel ratio will affect the stability in a certain extent and reducing the mixture ratio can restrain the instability. Reduction of hydrogen injection pressure has little effect on combustion stability.