波瓣喷管引射-混合器的数值研究与验证

Numerical computation and examination of a lobed mixer-ejector

关键词:  喷管  引射器+  混合机  数值计算

Key words:  Nozzle  Ejector~+  Mixer  Numerical calculation

摘要:

对基于CFD数值预测波瓣喷管引射 混合器引射流量比的计算方法进行了探讨,在计算过程中,主流进口采用速度边界条件,二次流进口采用总压压力边界条件,混合流出口采用静压压力边界条件,两者均设置为环境大气压力,与相关实验数据的对比验证表明计算结果与实验结果仅相差10%左右;同时通过改变混合管结构参数,得到了混合管结构参数对引射 混合特性的影响规律,进一步揭示了波瓣喷管有利于强化引射 混合的内在机理。在波瓣喷管出口对应于波谷区域存在一个相对低的静压区,对于引射 混合器系统存在一个最优的性能设计点,计算结果符合物理过程本质。

Abstract:

A research on the analytical prediction of pumping performance for the lobed mixer-ejector was performed by way of CFD technique. In the computation, the inlet of the primary flow used the velocity boundary condition. The total pressure boundary condition was applied to the inlet of the second flow and the static pressure boundary condition was applied to the outlet of the mixing flow, both were defined as ambient pressure. Compared with the experimental data, it is indicated that the relative error between the computational and experimental results is about 10%. A series of computations are conducted to obtain the effects of mixing-duct parameters on pumping-mixing performance and reveal further mechanism of the lobed nozzle on pumping-mixing enhancement, which shows that there exists a relative low static pressure region corresponding to the lobe valley at lobe nozzle exit and there is an optimum performance design for the particular mixer-ejector system. These results are verified with the physics nature.