固体火箭点火超压形成机理与影响因子研究

摘要

为研究固体火箭点火超压的形成机理和影响因子,以Ariane 5火箭固体助推器1/35缩比模型为研究对象,基于可压缩气体三维Navier-Stokes方程建立固体火箭尾焰流场的数学模型.同时,使用有限速率/涡耗散模型表征尾焰复燃反应,采用有限体积法求解火箭尾焰流场控制方程,得到箭体尾部近场的点火超压幅值与分布情况.与试验数据比较,数值结果较好的反映了点火超压的过程特性.进而,采用该数学模型和求解方法,研究了点火超压的影响因子.计算结果表明,尾焰复燃反应对点火超压的影响较小,与无复燃反应的计算结果比较,点火超压的峰值相对变化幅度不大于1.85％,点火超压的波形与分布特性的变化可以忽略;建压速率越快,点火超压峰值越大,且呈非线性比例关系增长;喷管膨胀比主要影响点火超压的波形,对其峰值影响较小.%To study the generation mechanism and influential factors of solid rocket ignition overpressure,a solid rocket exhaust plume flow field mathematical model based on three-dimensional Navier-Stokes equation is established,in which a 1/35 scaled model of an Ariane 5 rocket solid booster is taken as the research object.Meanwhile,a finite-rate reaction/eddy-dissipation model is introduced to account for the exhaust plume re-combustion,and the finite volume method is used to solve the exhaust plume flow field control equation.The ignition overpressure values and distribution around rocket after-body are obtained,which are consistent with the experimental results.Then,the mathematical model and numerical method are adopted to analyze the influence factors of the ignition overpressure.The results demonstrate that the exhaust plume recombustion reaction has little effect on the ignition overpressure.Compared with the numerical results without exhaust plume re-combustion reaction,the relative variation scope of the ignition overpressure peak is less than 1.85％,and the changes of the ignition overpressure distribution and wave shape are insignificant.However,the chamber pressurization slope and nozzle expansion ratio have a greater influence on the ignition overpressure.The higher the pressurization slope is,the higher the ignition peak is.And,there is a non-linear proportional relationship between them.The expansion ratio of the nozzle mainly affects the ignition overpressure wave shape,and it has a little influence on the peak of overpressure.