Dual-mode Scramjet Engine Flow Field Numerical Study

Supersonic Combustion Ramjet Engine (Scramjet) is the main power device of the future supersonic vehicle. It has the advantage of simple configuration, high efficiency, low weight and cost, etc, so it has a wide application perspective. The internal flow fields in scramjet are very complex, due to the interaction of shock waves, expansion waves, boundary layer and strong reactions. It gives challenge to numerical simulation. In this dissertation, the cell centered format finite volumemethod, q-ω turbulence model and finite rate reaction model are used to simulatethe scramjet flow fields, which can offer reference for the analysis and design.Firstly, the numerical methods are introduced, including the discretization of convection and viscous terms, time integration method, turbulence model, treatment of stiff reaction source and boundary condition. Based on the above methods, the original program is modified.With the modified program, the flow fields of scramjet isolator are simulated under different Mach number and different back pressure with uniform inflow conditions. The complex shock train structures are achieved. Take the real flow conditions into account, the inflow is always non-uniform. So the three-dimensional Inlet/Isolator integrated model is simulated. The result reveals that the non-uniform inflow has a significant impact on the isolator internal flow; exit Mach number and pressure varies acutely.Finally, the validation case, the mixing and combustion of supersonic hydrogen and air , is used to verify the program based the 9 species 34 elementary reaction model. The temperature and water mass fraction are compared with the experimental data. Then the flow fields of scramjet combustor with fix geometry and isolator are simulated at different inflow Mach number and the influence of direction of injection fuel to flow structure are analyzed.