火箭点火压力脉冲形成机理与影响因子分析

Generation Mechanism and Influence Factors Analysis of Rocket Ignition Pressure Pulse

关键词:  火箭  点火压力脉冲  燃气流场  一维线性波  数值计算

Key words:  Rocket  Ignition pressure pulse  Jet flow field  One dimensional linear wave  Numerical simulation

摘要:

为深入研究火箭点火瞬时压力脉冲形成机理，以火箭在地下有限空间内发射为研究对象，采用一维线性波理论分析了压力脉冲的形成机理和影响因子，并对压力脉冲幅值进行了估算。同时，采用计算流体力学方法，建立了基于三维可压缩气体Navier-Stokes方程的火箭发射燃气流场模型，详细揭示了压力脉冲在地下井内的幅值分布和演化规律。仿真结果表明，发动机燃烧室建压速率越大，井内的压力脉冲峰值越大，峰值出现的时间越早；燃气流密度越大，压力脉冲峰值越小，峰值出现的时间越晚；井筒越深，压力脉冲幅值越大。一维线性波理论分析和计算流体力学方法结果的压力脉冲峰值与试验结果比较，相对误差均不大于14.2%，表明这两种方法均能有效预示火箭点火压力脉冲幅值和分布规律。

Abstract:

To take more research on rocket motor ignition pressure pulse generation mechanism， the rocket launch in confined underground space was taken as the research object. One-dimensional linear wave analysis method was applied to expose the physical cause and influence factors for the pressure pulse， and the pressure pulse’s magnitude was estimated. Meanwhile， a rocket launch jet flow field’s numerical model based on three-dimensional Navier-Stokes equation for compressible viscid gas was proposed to characterize basic features of the rocket motor exhaust plume discharging in silo. Then， the computational fluid dynamics method was used to solve the numerical model and reveal the details of jet flow field， such as pressure pulse distribution and evolution rule in silo. Simulation results demonstrate that pressure pulse peak is higher and peak time is more advanced with motor chamber pressurization slope increasing. However， pressure pulse peak and peak time present an inverse rule with exhaust plume density increasing. The deeper the silo is， the higher the pressure pulse peak is. Compared with the test result， the relative error of the pressure pulse peak obtained by one-dimensional linear wave analysis method and CFD numerical simulation is no larger than 14.2%， which indicates that both methods are effective to predict rocket motor ignition pressure pulse values and evolution rule.