固体火箭发动机气-固两相近壁湍流特性大涡模拟研究OA北大核心CSTPCD

The internal flow field of a solid rocket motor is a typical two-phase turbulent flow,which profoundly impacts the combustion of propellant grain.In engineering practice,the Reynolds-Averaged Navier-Stokes(RANS)method is commonly used to-simluate two-phase flow problems,but its calculation accuracy is not high and the turbulent structures in the flow field cannot be re-solved.The internal flow field of a solid rocket motor under both pure gas and gas-solid two-phase conditions was numerically simu-lated by means of Large Eddy Simulation(LES)and the Discrete Phase Model(DPM).By analyzing the time-averaged and transi-ent flow fields and conducting spatio-temporal averaging of the physical parameters near the wall(i.e.,the injection surface),the turbulent characteristics near the wall were mainly studied.Spatio-temporal correlation analysis and Reduced-Order Variational Mode Decomposition(RVMD)were used to investigate vortex shedding near the wall.The results show that particles are concentrated in the central region of the internal flow field,with larger particles being closer to the center due to differences in inertia.The injection of particles reduces the axial velocity and temperature while increasing the pressure of the internal flow field due to the velocity lag and heat exchange between the particle and gas phases.Significant wall vortex shedding occurs in the internal flow field of the solid rocket motor,and the introduction of particles increases the irregular disturbances in the internal flow field,so that the positions of vortex shedding and breakup occur earlier and reduces the size of the vortex structures.The disturbances also result in more fragmen-ted observed vortices.Additionally,the introduction of particles mitigates the temperature gradient near the wall,suppressing unstable combustion phenomena.The presence of particles also reduces the radial velocity and increases the pressure near the wall,with the reduction and increase of approximately 1.8% .Analysis of pressure oscillations near the wall indicates that the presence of particles can suppress the generation of high-frequency pressure oscillations,eliminating the 1853 Hz oscillation mode observed under pure gas conditions and retaining only the 1425 Hz mode.The vortex shedding positions for the pure gas and gas-solid two-phase flow fields are located at x/m=0.54 and x/m=0.44,respectively,indicating that the vortex shedding position in the gas-solid two-phase flow field is further upstream.