Detached eddy simulation of a generic scramjet inlet and combustor

Results are presented which detail progress toward building the capability of simulating full scramjet powered vehicles. Important issues involved in the design of hypersonic, inward-turning inlets are disscussed and a process by which the performance of the inlets can be optimized is outlined. The geometry of the inlet is defined in terms of cubic ratio- nal Bezier curves. This allows for automated generation of high quality grids, as well as providing parameters which drive the optimizaiton process. The simulations used in the optimization of the inlets use a steady-state Reynolds-averaged Navier-Stokes model for turbulence closure. Simulations of the combustor section of a scramjet engine require a different modeling approach. A hybrid Reynolds-averaged Navier-Stokes and large eddy simulation methodology based on the detached-eddy simulation formulation is used. This allows for the large-scale unsteadiness of the ow to be resolved, which is key in simulating this type of ow accurately. The RANS portion of the method provides wall-modeling for large eddy simulation regions as well as fully modeling the turbulence in regions away from where mixing and combustion occur. This reduces the cost over a full LES. Preliminary results from simulations of two combustor configurations are presented. The first configuration involves the combustion of hydrogen injected through a normal, circular injector downstream of a small step. The second configuration involves a hydrogen-fluorine reaction in an expansion-ramp combustor. Finite-rate chemistry is used in the simulations; however, the current simulations do not include the effects of a subgrid model for the chemical source term. The simulations demonstrate the large range of time scales involved in combustor flows, which make an efficient solver with implicit time integration necessary. A low-dissipation, kinetic energy conserving numerical scheme is used in the simulation of the second configuration. This scheme resolves a larger range of turbulent scales on the same grid at minimal additional cost over standard upwind-biased schemes.