Mach reflection induced detonation in a reactive flow.

摘要

A comparison of a chemically reactive flow versus a non-reactive flow is made in this work to show the possibility of the presence of a detonation wave associated with a Mach stem also known as a Mach reflection wave. A reactive, inviscid, and unsteady flow over a two-dimensional wedge is observed. Then, it is compared to a non-reactive flow over the same geometry and under the same conditions. A range of deflection angles theta and incoming flow Mach numbers M1 is used in this study. The Euler equations are discretized using a finite-volume approach to ensure conservation and to allow proper treatment of discontinuities. A two-step explicit Runge-Kutta integration scheme is implemented together with a point-implicit treatment of the source terms to obtain a time-accurate solution. In addition, Roe's flux-difference splitting scheme extended to non-equilibrium flow is used for the cell face fluxes, and the MUSCL approach is used for higher-order spatial accuracy. For the purpose of constructing an efficient numerical tool, while maintaining a reasonable accuracy, a two-step global model has been selected and validated for a hydrogen-air mixture. After running several simulations and computations, the results are then compared to theoretical Chapmann-Jouguet data. A thorough discussion and analysis is also made for each case included in this work. The variable parameters chosen for this study are the angle of deflection theta, the incoming flow Mach number M 1, the initial pressure P1, and the initial temperature T1 as well as the length of the wedge and the height of the domain. It was found that under certain conditions a Mach stem is formed which triggered a detonation in the flow. The detonation and the formation of the mach stem were shown to be dependent on the flow parameters mentioned above and independent on the geometry and the size of the domain.