高温引气对亚燃冲压燃烧室性能影响的研究

Investigation of Hot Air on Performance of Ramjet Combustor

将高温引气加热煤油的方法、凹腔火焰稳定器和支板喷注器结构应用于亚燃冲压发动机燃烧室中,以提高煤油的点火能力和火焰稳定性。采用有限体积方法求解雷诺平均N-S方程及组分方程,对无引气和有引气时燃烧室内的流场结构进行了数值研究,对比研究了引气温度对燃烧及发动机性能的影响。研究发现,引气温度越高,燃料喷注对流场和温度场的影响越小,燃料分布越均匀;与无引气相比,引入高温气体虽然使总压恢复系数有所降低,但是混合效率、燃烧效率和燃烧室比冲都有提高;特别是有引气(煤油温度T=500K)时,在喷注点后X=480mm处混合效率提高了7.03%并混合完全,在燃烧室出口总压恢复系数降低了5.34%,燃烧效率和比冲分别提高了17.51%和20.29%。引入高温气体加热液态煤油省略了煤油的雾化和汽化过程,增强了燃料与空气掺混,改善了燃烧稳定性,有利于提高燃烧室整体性能。

In order to enhance the ability of kerosene＇s ignition and flame stability in ramjet combustor,the method that hot air was imported to heat kerosene,cavity flameholder and strut injection structure were applied to ramjet combustor. Reynolds-averaged Navier-Stokes equations with species conservation equation were solved based on the finite volume method. Numerical simulations were conducted to study the flow field in the ramjet combustor with and without hot air imported,and the effects of the air temperature on the combustion and engine performance were compared. It is found that the influence of fuel injection on flow field and temperature field is smaller and the fuel distribution is more uniform when the temperature of hot air is higher. Compared with no hot air imported,although the total pressure loss increase in some extent,the fuel-air mixing efficiency,combustion efficiency and the specific impulse of the combustor are improved in a remarkable extent with hot air imported; especially with hot air imported（kerosene temperature T=500 K）,mixing efficiency increased by 7.03% and mixed completely at the location of X=480 mm after the injection point,total pressure recovery coefficient reduced by 5.34%,combustion efficiency and specific impulse increased by 17.51% and 20.29% respectively at the combustor exit. Due to the hot air imported to heat kerosene,the process of atomization and vaporization of kerosene is omitted,which enhances the mixing of fuel and air and improves the stability of combustion. Therefore,it is good for improving the combustor performance when hot air is imported to heat kerosene in ramjet combustor.