基于CFD-DEM算法的固体火箭发动机气-固两相流模拟

Study of Gas-Particle Flow in Solid Rocket Motor Based onComputationalFluid Method-Discrete Element Method

关键词:  固体火箭发动机  离散元方法  气固两相流  数值模拟

Key words:  Solid rocket motor  Discrete element method  Gas-particle flow  Numerical simulation

摘要:

针对固体火箭发动机中含金属推进体系中颗粒冲刷烧蚀及推力两相流损失的难题，基于连续相-离散元（CFD-DEM）耦合模型，考虑颗粒间的碰撞力与非碰撞力以及颗粒-气流作用力等，对固体发动机中气-固两相流进行了数值模拟研究。研究结果表明，相比于传统的双流体模型及轨道法，CFD-DEM能提供更丰富的粒子尺度信息包括粒子的运动轨迹、颗粒间的碰撞、颗粒受力情况等等；以及粒子相与气相相互作用过程，粒子相与壁面相互作用等。粒子的碰撞在喷管收敛段壁面、喉部区域以及喷管扩张段中心区域发生，与壁面的碰撞在收敛段壁面位置，且颗粒在该区域角速度较大，气相-颗粒曳力最大值出现在气相加速区域。单个粒子尺度的流场数据为固体发动机气固两相流流场的认识提供了更加丰富的信息，并为粒子聚集聚合及对烧蚀层冲刷等提供研究基础。

Abstract:

The multi-phase flow in Solid Rocket Motor (SRM) is a typical complex multi-scale flow, which plays an important role in influencing the performance and safety of SRM. The particle erosion on ablate layer and the thrust lose of gas-particle flow are the long-term concerns in solid propellant system. Compared to the conventional Two Fluid Model (TFM) and Lagrange Method, the Discrete Element Method (DEM) based gas-particle simulation is able to describe the particle behavior on microscopic level, such as particle-particle collides, particle-gas interaction force and particle-wall interaction force, and hence it has extensive applications in different areas. The Computational Fluid Dynamic (CFD) is coupled with DEM to predict the gas-particle flow in SRM. The results indicate that compared to the conventional methods, CFD-DEM could provide rich information, such as particle-particle contacts, particle-gas interactions, and all sorts of forces acted on particles. Particles are accumulated in the wall region of nozzle convergent part, in the throat, and in the central area of nozzle divergent part, which subsequently leads to frequent collides among particles and high angular velocity of particles. Drag force appears higher in the region where gas is accelerated. CFD-DEM simulation provide a new way to study the gas-particle flow in SRM, and reveal rich information on micro- and macro-level, thus would deliver new perspectives to understand the multi-phase flow in SRM, the particle erosions and so on.