中、小过载下战术发动机内流场数值模拟

NumericalSimulationofFlowFieldofTacticalSRMwithLow andMediumAcceleration

关键词:  战术发动机  中、小过载  两相流  三维数值仿真

Key words:  Tactical solid rocket motor  Low and medium acceleration  Two-phase flow  Three-dimensional numerical simulation

摘要:

针对战术发动机的飞行条件，建立了固体发动机过载条件下内流场两相流计算模型，开展了 3种典型中、小飞行过载下的流场计算，详细分析了燃烧室内凝相颗粒冲刷参数分布，并初步分析了颗粒聚集状态与绝热层烧蚀之间的关系。研究结果表明:(1)当横向过载达到一定程度，在发动机筒段绝热层表面，在承载面沿着流场方向会形成一条粒子浓度缓慢增大的聚集带，而在非承载面粒子分布较为稀疏。(2)过载大小对颗粒冲刷速度的影响不明显，主要原因是燃气本身对颗粒运动的轴向加速很大，而过载的作用体现不明显。(3)燃烧室中粒子密集区一定程度反映了该部位的烧蚀环境较为严酷，绝热层烧蚀主要由于凝相粒子低速聚集导致了局部热增量加剧并引起了颗粒的二次聚集效应。因此，长时间中、小过载下，为了缓解燃烧室绝热层局部的严酷烧蚀环境，在已知粒子冲刷参数分布下，可增加局部绝热层设计厚度，调整发动机的飞行姿态使承载面呈现正负交替的过载以及增加发动机自身旋转动作。

Abstract:

According to the flight conditions of the tactical SRM(Solid Rocket Motor)，a three-dimensional numerical model of two-phase flow was established for overload conditions. Flow field calculations were carriedout for three different types of working conditions under small and medium-sized overload，respectively. The pa. rameter distribution of the condensed particles in combustion chamber was analyzed，and a preliminary analysisof the effects of aggregation state of particles on the insulation ablation was performed. The results show that:(1) When the lateral acceleration is larger than a certain degree，an accumulation belt will be formed on the cylin.der section of the motor insulator surface as particle concentration increasing slowly on the bearing surface alongflow direction. However，particledistribution issparseon the non-bearingsurface.(2)The contribution of mo. tor overload on the particle velocities is not significant. The main reason is that the axial acceleration of particlesis mainly derived from the gas itself.(3)To some extent，particle aggregation zone shows the position of relative.ly severe ablation environment in the combustion chamber of motor. The insulation ablations mainly due to thelow velocities of particles aggregation lead to the increasing of heat increment on the local insulator surface， and cause particles focalized secondly. Thus，under low and medium acceleration with long operation time，in or. der to alleviate the harsh ablation environment of local insulator in chamber combustion，according to the known particle distribution parameters，the design of motor should increase the thickness of local insulator，and adjustthe flying attitude to make the bearing surface rendering acceleration alternating and increase the rotation actionof motor.