可燃气体中激波聚焦的数值模拟

【作者】 唐敖；

【导师】 董刚；

【作者基本信息】 南京理工大学 ， 热能工程， 2005， 硕士

【摘要】 本课题源于自然科学基金《收敛激波与火焰作用对燃烧转爆轰的强化机制》中的一部分,利用数值方法对入射激波经抛物壁反射后聚焦的过程进行了深入的研究。 本文首先使用二维轴对称的多组分化学反应流的守恒型欧拉方程作为控制方程,利用改进的高精度的二维波传播算法计算对流项,选用甲烷/空气氧化反应的19步机理模拟化学反应过程,对化学反应源项进行计算。在此基础上编制的适用于非正交网格的计算程序,对甲烷/空气可燃气中,入射激波经抛物壁反射后聚焦的过程进行了数值模拟。在获得计算结果后,首先与实验结果进行了比较,验证了算法的合理性和结果的准确性。接着通过对计算结果的研究,讨论了入射激波强度、抛物壁深度以及可燃气体化学反应活性对激波聚焦后可燃气体着火方式的影响,同时还分析了流场结构的变化。数值计算结果表明,激波聚焦在气体动力学焦点产生高温高压,而可燃气体在激波聚焦后可能发生未着火、爆燃和爆轰三种情况。入射激波强度越大,抛物壁的深度越深,可燃气体化学反应活性越强,激波聚焦后可燃气体越容易发生爆轰。更多还原

【Abstract】 As a part of the project "enhancement mechanism of focusing shock-flame interactions on deflagration-to-detonation transition", the numerical investigation was carried out to study incident shock wave focusing on parabolic reflector in CH₄/AIR mixture.The multi-component, reactive, two-dimensional axisymmetric Euler equations were employed to simulate the process. The modified high-resolution wave propagation algorithm was adopted to solve the convection term of the equations. A detailed 19 step chemical mechanism of CH4/AIR was used to solve the chemical source term. Then a program was extended to simulate the process of shock wave focusing on parabolic reflector in CH4/AIR mixture. The computational results were compared with the experimental results, and the reasonable agreements are obtained. The computational model is then extended to study the effects of controlled parameters, such as incident shock wave Mach number, depth of the reflector and the chemical activity of the mixture, on the combustion mode after the focusing. And the changes of the flow structure were also investigated. The computational results showed that the three different patterns, namely no ignition mode, deflagration mode and detonation mode could occur with the variation of these parameters. Strong incident shock wave, deep reflector, and/or high chemical activity of mixture tend to generate detonation in the combustible gaseous mixture.更多还原