【作者】 杨丹；

【导师】 郜冶；

【作者基本信息】 哈尔滨工程大学 ， 航空宇航推进理论与工程， 2006， 硕士

【摘要】 现代固体火箭发动机广泛采用含金属复合推进剂，特别是含铝复合推进剂，以达到提高比冲的目的，铝的燃烧产物氧化铝粒子加入燃气后将形成典型的两相流动。两相流动会对发动机性能产生较大影响，高速运动的固体颗粒可能对发动机壳体以及喷管壁面产生冲刷。许多大型固体火箭发动机采用潜入式喷管，含铝推进剂燃烧时产生的比较大的固体颗粒无法进入喷管，会沉积在潜入喷管背壁空腔，就形成所谓的熔渣。 对气固两相流进行数值研究的模型基本可以分为两类：颗粒轨道模型(Lagrangian)和双流体模型(Eulerian)。这两种模型对气相的计算均采用已经比较成熟的单相流算法，其差别主要在于对颗粒相的处理。本文将两种模型用于固体火箭发动机内流场的两相流计算，利用大型CFD软件FLUENT中的颗粒轨道模型、混合物模型(即欧拉模型)对文献中的经典算例进行计算，并将结果与文献中结果进行对比验证。再将以上两种模型用于某潜入式喷管发动机，并比较其结果。 本文得到以下结论： 1．颗粒轨道模型能够模型有复杂经历的颗粒相，如颗粒的蒸发或凝结、沉积或冲刷，并可以清楚地看到粒子的运行轨迹。但对于模拟两相之间的耦合作用其效果不佳，且不能给出连续的颗粒速度和浓度的空间分布。 2．双流体模型能够全面考虑颗粒的湍流输运，并用统一的方法处理颗粒及流体相，两相间的耦合作用较强。其缺点是不能模拟颗粒的复杂变化，当颗粒分组数较多时，所需计算存贮量过大。 3．两相流场中的气相速度均小于纯气相流动，且尺寸小的粒子比大粒子使气相速度降低的程度更大，这与物理现象是一致的。颗粒质量分数不同，其对气相流场的影响程度是不同的，这一点在Eulerian方法中更能得到很好的体现，而Lagrangian方法颗粒相不占压力，因此其影响程度很小。更多还原

【Abstract】 Modern solid rocket motor usually uses aluminum propellant to improve the capability and restrain the unstable combustion. Alumina particles and the gas will form the typical two-phase flow. Two-phase flow affects the motor character. Particles with high speed maybe erode the walls of motor and nozzle. Recently, flush type nozzle is employed in many large solid rocket motors. Larger solid particles generated by aluminum propellant can’t enter the nozzle and deposit in the cavity at the back wall of the flush type nozzle, which results in the so-called slag and causes the propellant energy loss and increases passive weight of the motor.In numerical simulation of two-phase flow, there are two approaches (Lagrangian approach and Eulerian approach) typically used for modeling fluid-solid flows. The former treats the fluid phase as continuous phase and the solid phase as dispersed phase and predicts the particle trajectories in the fluid phase as the results of forces acting on particles. The latter treats the solid as a certain kind of continuum and solves two continuum equations for both fluid and solid phase. Base on the advantages and disadvantages of the two approaches, we simulate the two-phase flow in solid rocket motor with these two approaches, and discuss the flow from different aspects. Then simulate the classic examples in the references with the Lagrangian approach and Mixture approach (Eulerian approach) in the big CFD software FLUENT, and compare with the result in the references. At last, we simulate the two-phase flow in some flush type nozzle with the two approaches.The conclusions from the calculation are as follows:1. Lagrangian approach cannot model the solid phase with complex experiences, like evaporation or coagulation, the deposition or washes out, and may clearly see the particle trajectories. It also cannot produce the continual particle speed and the density spatial distribution.更多还原