隔层式双脉冲发动机尾部点火过程流固耦合特性研究

Fluid-Solid Coupling Characteristics Study on Ignition Process in a Dual Pulse Motor with Aft-End Igniter and Soft Pulse Separation Device

为研究隔层式双脉冲发动机Ⅰ脉冲尾部点火过程对隔层和Ⅱ脉冲药柱结构完整性的影响,以雷诺时均Navier-Stokes方程、k-ωSST湍流模型和固体推进剂热传导方程为基础,基于耦合传热方法建立推进剂点火与燃烧加质模型,同时结合流固耦合方法,详细分析了点火过程中燃气的非定常流动特性以及燃气冲击作用下隔层和Ⅱ脉冲药柱结构的力学特性。计算结果表明,尾部点火药气体喷射入药柱后端内孔和翼槽内形成回流区,导致翼槽侧表面首先点燃,同时迅速产生了二次着火点,加快了火焰传播过程,提高了升压速率;点火过程中燃烧室内初始低温气体被挤压至燃烧室头部,并与高温燃气持续相互作用,引起燃烧室头部压力剧烈振荡;点火冲击过程中,隔层表面压力差距较大,隔层外表面上等效应力最大值为3.7MPa,最大总变形量达10.1mm。

In order to investigate the impact of the first pulse ignition process of dual pulse solid rocket motor with an aft-end igniter on the soft pulse separation device and the second pulse grain,based on the Reynolds time-averaged Navier-Stokes equations,the k-ω SST turbulence model and solid propellant heat conduction equation,the ignition and add-mass model of propellant is established based on the fluid-thermal couple method,combined with fluid-solid couple method,the unsteady flow characteristics of the burning gas and the mechanical properties of the soft pulse separation device and the second pulse grain under ignition shock are analyzed.The results show that the tail ignition gas is injected into the inner channel and finocyl at the rear end of the grain to form a reflux area,resulting in the first ignition of the side of finocyl,and the second ignition point is quickly generated,which speeds up the flame spreading processes and increases the rate of pressure rise.During the ignition process,the original low-temperature gas is squeezed to the head of the combustion chamber and interacts with the ignition gas continuously,resulting in violent oscillation of the pressure at the head of combustion chamber.In the process of ignition impact,the pressure difference on the surface of the pulse separation device is large.The maximum equivalent stress on the surface of the pulse separation device is 3.7MPa and the maximum total deformation is 10.1mm.