二级轻气炮活塞入锥和发射管烧蚀问题研究

The high pressure contraction section of a Two-Stage Light-Gas Gun (TSLGG) can improve the acceleration process of the projectile, while it brings the problem of intensive fluid-solid coupling when the piston enters the contraction section, as well as the launch tube erosion induced by the high temperature gas. The problems exert powerful effects on the launching capability, the structural-load-carrying capacity and the service life. In this project we propose to take consider of the effects of real gas, two-dimension and hydrogen dissociation in the flow simulation; and think through the friction, the heat transfer, the phase transition and the constitutive model change of the piston. By considering the factors above, a multi-field coupling model of the piston entering the contraction section process will be set up to simulate the piston deformation and the states of the HTHP flow field. Therefore, the law governing the influence of the piston entering process on the TSLGG performance will be disclosed. Meanwhile, an erosion model and a quantitative damage valuation system for the launch tube will be built to investigate the launch tube erosion mechanism and predict the safety range of the TSLGG operation. Then, a launching velocity prediction software of TSLGG will be developed by considering the effects of piston entering and launch tube erosion. Based on the work above, the aims of improving TSLGG performance and optimizing the launching parameters can be reached, and the results of this project will be beneficial references for TSLGG design and reform.

二级轻气炮的高压锥段结构能够有效改善弹丸加速曲线，但也带来活塞入锥剧烈流固耦合和气体高温诱导发射管烧蚀等问题，对气炮的发射能力、结构承载能力和使用寿命产生重要影响。本项目拟综合考虑入锥过程中流场的真实气体效应、二维效应和高温解离效应，以及活塞的摩擦、传热、相变和本构变化，建立活塞入锥过程多物理场耦合模型，实现活塞在高温高应变率下的粘塑性变形和高温高压流场状态的准确描述，以揭示活塞入锥效果对二级轻气炮性能的影响规律。同时，考虑发射管在高温气体对流加热下的升温、相变过程，建立二级轻气炮发射管烧蚀模型和损伤定量评估系统，探明发射管烧蚀机制，给出发射参数的安全区间。在上述工作基础上，建立考虑活塞入锥效应和发射管烧蚀影响的二级轻气炮弹丸发射速度预测软件，实现提高弹气炮性能和优化发射参数的目标，并为二级轻气炮的设计和改造提供有益的参考。

二级轻气炮是高压物理、超高速撞击和工程防护等研究方向的重要实验手段，提高弹速上限、延长使用寿命、降低运行成本、减小安全风险是气炮发展的目标。活塞入锥是二级轻气炮发射最关键、最复杂的阶段，发射时产生的最大应力、最大压强、最高温度和最大变形都集中出现在这一阶段，活塞的入锥效果决定了气炮的发射性能。.本项目采用理论建模、数值仿真和实验校验相结合的研究方法，综合考虑入锥过程中气体工质的复杂流动、活塞的摩擦及对流换热作用下的发射管烧蚀，建立了活塞入锥过程多物理场耦合数值仿真模型，可准确描述活塞的运动和变形过程及气炮内高温高压气体的流动状态；建立了二级轻气炮发射管烧蚀模型和数值仿真系统，可评估气炮发射对发射管的损伤；建立了二级轻气炮发射全过程数值仿真模型，实现了二级轻气炮锥段参数分析与发射参数优化。研究结果表明：（1）高压气体二级炮的工作过程与火药二级炮有明显差异，活塞入锥时弹体已经完成发射，入锥速度是决定入锥深度的关键参数；（2）He工质对发射管的烧蚀显著高于H2工质，烧蚀在破膜-弹体离开发射管阶段发生。（3）本项目研究的100/30mm二级轻气炮的最佳活塞质量为18.6kg，最佳锥角为16.3度。.本项目的研究内容阐明了活塞入锥和发射管烧蚀这两个流、固耦合问题及其对二级轻气炮发射性能的影响，研究成果为提高气炮发射性能和优化发射参数提供了有力支撑，可为二级轻气炮的设计和改造提供理论指导。