边界形状对4股燃气射流扩展稳定性影响的数值模拟

为研究提高整装式液体发射药火炮燃烧稳定性的方法，从充液室结构出发，分析了冷态条件下边界形状对4股燃气射流扩展稳定性的影响。采用高速数字摄像系统，记录了4股燃气射流在5级圆柱渐扩型观察室中扩展过程。在此基础上，建立了气体与液体相互作用的三维非稳态数理模型，模拟了4股燃气射流在5级圆柱渐扩型、圆锥型和圆柱型观察室中扩展过程，获得了射流场三维两相分布图、压力和温度分布图。研究结果表明：4股燃气射流在5级圆柱渐扩型观察室中轴向位移的模拟值与实验结果较吻合；圆柱渐扩型和圆锥型观察室都可以增强燃气射流的径向扩展，有效抑制Taylor空腔与Helmholtz不稳定效应的正反馈机制；圆柱渐扩型由于台阶逐渐诱导作用，近喷孔处温度场无剧烈脉动，射流扩展更加稳定。

Numerical Simulation of the Influence of Boundary Shape on the Expansion Stability of Four Combustion-gas Jets

The influence of boundary shape on the expansion stability of four combustion-gas jets under cold conditions is discussed to study an approach to improve the combustion stability of bulk-loaded liquid propellant gun. High-speed digital video recording system is used to record the expansion process of four combustion-gas jets in a five-stage cylindrical stepped-wall type observation chamber. On this basis, a three-dimensional unsteady mathematical model of gas-liquid interaction is established to simulate the expansion processes of four combustion-gas jets in a five-stage cylindrical stepped-wall type, conical and cylindrical observation chambers. The three-dimensional two-phase distribution chart, pressure and temperature distribution chart of jet field were obtained. The results show that the simulated results of axial displacements of four combustion-gas jets in the five-stage cylindrical stepped-wall type chamber coincide well with the experimental results. Both the cylindrical stepped-wall type chamber and the conical chamber can enhance the radial expansion of combustion-gas jet and effectively suppress Taylor cavity and Helmholtz instability; due to gradual induction of stepped-wall in the cylindrical stepped-wall type chamber, the temperature field near the nozzle has no severe pulsation and the jet expansion is more stable.