REACTIVE AND VISCOUS-FLOW IN HYPERSONIC NOZZLES

In high-enthalpy hypersonic facilities, the airflow at the exit of a convergent-divergent nozzle is affected by the high reservoir enthalpy level because chemical and vibrational nonequilibrium processes take place in the nozzle. The models in the test section are generally located at the nozzle exit, and so the knowledge of the nozzle flowfield is of upmost importance to obtain the upstream conditions for the flow around the model. This flowfield is studied numerically by solving the unsteady laminar axisymmetric Navier-Stokes equations, coupled with those describing the chemical and thermal nonequilibrium processes in the real-air gas mixture. The equations are solved by an implicit time-dependent finite difference method, including a flux-splitting technique in the implicit operator. Results show the flowfield in conical and contoured nozzles for different high-enthalpy reservoir conditions. The chemical and vibrational nonequilibrium behavior in the boundary layer and in the core flow is also emphasized.