固体运载火箭级间热分离流场三维数值模拟

Numerical study of the solid rocket stage separation flow field

常规含铝17%的复合推进剂完全燃烧后火箭喷流中Al2O3的质量分数高达32%,如此高质量分数的凝相粒子会导致分离过程中火箭前、后封头受力情况发生变化。首先基于开排焰窗口式固体运载火箭级间热分离过程,建立火箭级间热分离的三维流场数值仿真模型。随后通过数值模拟分别研究了考虑和不考虑凝相颗粒影响条件下的固体运载火箭级间热分离过程的级间段流场特征。结果表明,固体火箭级间分离过程中,级间流场变化剧烈,级间段流场存在激波、膨胀波、流动分离、边界层分离和涡旋等复杂的流动现象;随着分离距离的增加,下面级前封头上的平均压强在振荡后持续提高;上面级后封头上的平均压强前段缓慢上升、后段迅速下降,并逐渐趋近于环境压强。所得结果为指导级间段热防护设计以及火箭级间分离方案设计提供了理论依据。

After the conventional aluminum 17%composite propellant is fully burned,the mass fraction of condensed particles(Al2O3)in the rocket jet is up to 32%.The condensed particles with such a high fraction will cause the stress of the front and rear surface of the rocket changed during the separation process.In this paper,based on the separation process with flame window,a three dimensional flow field numerical simulation model of rocket stage separation is established.Then,the characteristics of the flow field in the process of solid propulsion launched vehicles separation are studied,both considering and without considering the effect of the condensed particles.The results show that during the separation process of solid rocket,the flow field varies violently,and there are complex flow phenomena such as shock wave,expansion wave,flow separation,boundary layer separation and vortex in the flow field.With the increase of separation distance,the average pressure on the front head of the lower stage increases contin uously after oscillation.The average pressure on the upper rear head is slowly rising,whereas the posterior decreases rapidly,which gradually approaches the ambient pressure.This paper provides a theoretical basis for guiding the thermal protection design of the inter stage section and the design of rocket separation scheme.