Numerical Simulation Of Shock Wave Focusing In The Combustible Gas

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.