N_2O/HTPB固液发动机燃烧室结构对药柱燃面退移特性的数值模拟

Influence of chamber structure on regression rate of solid fuel in N_2O/HTPB hybrid rocket motor

针对采用N_2O/HTPB推进剂的某固液火箭发动机,分析研究燃烧室长径比、前燃室长度、补燃室长度以及喉径等结构参数对固体燃料热解表面燃面退移速率的影响。通过建立一种基于流场与固体燃料之间耦合传热和PDF燃烧模型的数值计算方法,并经算例验证后,说明此数值模拟方法的合理性和正确性。因此,应用此数值模拟方法分别计算了燃烧室各结构参数对固体燃料热解表面退移速率的影响:药柱长径比对燃面退移速率影响较大,随着药柱内径的不断增大,退移速率逐渐减小;随着前燃室长度的增大,燃面退移速率也相应增加,但幅度较小;而补燃室长度以及喉径对退移速率基本无影响。适当增加补燃室长度,可增强氧化剂与燃料热解气体的掺混效果,从而提高燃烧效率。

The effect of chamber structure parameters on regression rate of N20/HTPB propellant in hybrid rocket motor has been studied by the numerical simulations method,which is based on thermal coupling at burning face and PDF combustion model, such as the draw ratio,the pre-chamber,post-chamber,the throat diameter and so on.An illustrative example proves that the method is reasonable and feasible.The results show that the draw ratio of grain has a great impact on the regression rate.As the draw ratio increases,the regression rate decreases.In comparison,the pre-chamber,post-chamber and the throat diameter have little effect on regression rate.The appropriate length of post-chamber can enhance the extent of mixing for pyrolysis gases of the oxidants and fuels, and hence the combustion efficiency has been improved.