The stepback and partial grid techniques were used in the numerical simulation of laminar viscous reacting flows past cones at incidence. The stepback technique is a method for computing exactly flows which are truly conical, and can be an effective approximate method for nearly conical flows such as viscous flow past cones. The partial grid technique uses a stepback solution as the upstream boundary condition for a time-marching calculation, and is more accurate than the stepback method. Both frozen and chemically active equilibrium flow were considered, using the Ideal Dissociating Gas model. Computations were performed for frozen hypersonic flow past a 10° half-angle cone inclined at 24° incidence, and for hypervelocity flow past a 15° half-angle cone at 30° incidence with active dissociation and recombination chemistry. These computations were compared with experiments, and the effects of equilibrium and non-equilibrium chemistry were observed. These calculations also show that the effects of chemistry on heat transfer and separation location are small and of the same order as the errors associated with the stepback method. Therefore, for high accuracy in computing reacting flows, the partial grid method should be used.
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