基于五阶WENO格式的燃气在药床中流动过程二维两相流研究

为研究内弹道初始阶段中心点火管燃气在膛内药床中的流动特性和传播规律，设计了可视化点传火实验平台，并进行了膛内假药床的点传火实验。基于加权本质无震荡(weighted essentially non-oscillatory, WENO)格式，构造了膛内轴对称二维内弹道两相流模型，对膛内燃气在假药床中的流动过程进行数值模拟。计算结果与可视化实验结果符合较好，全局压力平均误差为5.35%。表明数值计算准确地描述了燃气流动特性，完整地呈现了点火管燃气在假药床中的发展过程。在点火初始阶段，膛内压力径向效应明显，气相沿径向传播较快，药床药粒基本不会发生运动；随着燃气逐渐在膛内传播，膛内压力呈现径向一致、轴向梯度分布的特征，在压力梯度作用下，气相轴向速度开始占据主导，径向速度在膛底和中部区域减小为零，而固相速度随气相速度变化而变化；气相在到达弹底前，由于固相颗粒的壅塞，会提前出现速度反向波动现象。

Two-dimensional numerical simulation on gas-solid two-phase flow induced by combustion gas flow in a chamber based on a fifth-order WENO scheme

In order to explore the flow characteristics and propagation law of combustion gas from the central ignition tube in the initial stage of internal ballistic, a visual experimental platform was designed to carry out ignition experiments with the substituted particle bed in the chamber. A high-speed camera system was used to capture the gas flow and flame propagation in the chamber, and a dynamic data acquisition and analysis system with pressure sensors was applied to record the pressure data at characteristic positions in the chamber. A two-dimensional, axisymmetrical, two-phase flow model of internal ballistics was constructed to simulate the flow process of the gas in the substituted particle bed based on a weighted essentially non-oscillatory (WENO) scheme, and the time term was determined by the third-order TVD Runge-Kuta method. The calculated results are in good agreement with the visual experimental results, and the global pressure average error is 5.35%. It indicates that the numerical simulation can accurately describe the gas flow characteristics and present the development process of the gas from the ignition tube in the substituted particle bed. The radial effect of the chamber pressure is obvious, and the gas moves rapidly along the radial direction, and the substituted particle basically does not move in the initial stage of ignition. Moreover, with the gradual propagation of the gas in the chamber, the chamber pressure is characterized by a radial uniformity and an axial gradient distribution. Under the action of the pressure gradient, the axial velocity of the gas phase begins to dominate, and furthermore, the radial velocity decreases to zero in the bottom and the middle region of the chamber, while the solid phase velocity varies with the gas phase velocity. In addition, before the gas reaches the bottom of the right end, the inverse velocity fluctuation appears in advance due to the solid particle congestion.