横向过载下考虑颗粒聚合行为的颗粒阻尼特性研究

Study on particle damping properties considering particle aggregation under transverse overload

固体火箭发动机的横向过载内会改变凝相颗粒的运动轨迹,增大颗粒与颗粒,颗粒与壁面的碰撞概率,改变凝相粒子的粒径和浓度分布,使颗粒的阻尼特性发生变化,造成发动机的燃烧不稳定。基于CFD-DEM数值模拟方法,耦合颗粒碰撞聚合模型,实现了过载下的颗粒碰撞、聚合及流动过程的数值仿真。数值结果揭示了在不同横向过载下粒径分布、颗粒空间分布,以及颗粒阻尼特性的变化特征。横向过载下,颗粒横向偏移显著增加,颗粒间的碰撞概率增大,并且碰撞概率随过载作用时间增加大幅度提高。颗粒间因碰撞聚合易生成的大粒径颗粒,大粒径颗粒的产生使得颗粒空间分布更具不均匀性,进而导致颗粒的阻尼值明显降低,最终影响发动机的燃烧稳定性。

The transverse overload of solid rocket motor will change the trajectory of condensed particle,increase the collision probability between particles and particles,particles and wall,change the particle size and concentration distribution of condensed particles,consequently reduce the damping characteristics of particles leading to the combustion instability.Based on the CFD-DEM numerical simulation method,coupled with the particle collision-aggregation model,was conducted the numerical simulation of particle collision,aggregation and movement under overload.The numerical results reveal the variation characteristics of particle size distribution,particle space distribution and particle damping characteristics under different transverse overloads.Under transverse overload,the particles significantly move and accumulate in transverse direction,and then the collision probability between particles increases,and the collision probability increases significantly with the increase of overload time.Large particle size particles are easily generated due to collisions polymerization between particles.The generation of large particle size particles makes the spatial distribution of particles more uneven,which leads to a significant reduction in the damping value of particles,and ultimately affects the combustion stability of the motor.