Plasma flow modeling for Huels-type arc heater with turbulent diffusion

In this study, we developed an analytical model for the flow field in the Huels-type arc-heated wind tunnel (L2K) of the German Aerospace Center. This flow-field model can be used to accurately reproduce the discharge behavior in the heating section and expansion in the nozzle section of L2K. It includes the radiation transport and turbulent flow as well as thermochemical nonequilibrium models, which are tightly coupled with electric field calculations. In addition, we considered the turbulent diffusion model for the mass conservation of the species and performed numerical simulations for several cases with and without the turbulent diffusion model. Computations were conducted to obtain the general characteristics of an arc-heated flow containing an arc discharge and supersonic expansion. We verified that radiation and turbulence play important roles in the transfer of heat from the high-temperature core flow to the outer cold gas in the heating section of L2K. In addition, we performed parametric studies that involved varying the degree of turbulent diffusion. The results showed that turbulent diffusion has a large influence on the formation of the arc discharge in the heating section and on the enthalpy distribution at the nozzle exit.