Influence on Flow Field of Hot Launch in a W-Shaped Underground Space by Water Injection

The water spray system is used to improve the flow field in the thermal launch process of missiles in underground spaces, with the aim of reducing the peak value of pressure pulse, alleviating pressure oscillation, and reducing the temperature of flow field through “decompression and cooling”. In this study, a gas-liquid two-phase flow control equation is established by combining the three-dimensional viscous compressible Navier-Stokes equation, mixture multiphase flow model, and phase change model. The mathematical model and numerical method are validated using gas jet scaling test data. Computational fluid dynamics (CFD) numerical calculation method is used to analyze the influence of the water spray system on the flow field environment during the missile's underground space launch process. The results show that the environmental characteristics of the flow field in the underground space during the thermal launch of the missile are effectively improved by establishing a water spray system at the bottom of the W-shaped underground space. The water spray system has a good suppression effect on the initial overpressure phenomenon. The bottom pressure oscillation is reduced from 8 times to 4 times. The pressure changes slowly up and down at 1 atm, with the maximum pressure only about 1. 20 伊 10 Pa. The initial overpressure peak is reduced, and the frequency and amplitude of the pressure oscillation are reduced, achieving the decompression effect. Through the process of violent vaporization of liquid water and momentum exchange, the phenomenon of gas backsplash is strongly and effectively suppressed by the water spray system. The gas is confined at the bottom of the cylinder, and the maximum temperature at the bottom of the missile is reduced from 3 000 K to about 400 K, achieving the “cooling” effect.