Effect of surface catalysis on measured heat transfer in expansion tunnel facility

The effect of gas or surface interaction in the form of surface catalytic recombination occurring in hypersonic flows as the reacting gas behind the bow shock dissociates can have a significant impact on the resulting heat transferred to the surface. Recombination that occurs either in the boundary layer or locally at the surface increases the net level of heat transferred to the surface due to the chemical energy released from the recombination process. The DPLR code has several options available to model surface catalysis at the solid surface boundary. Boundary conditions for each reacting species are individually computed from species mass balance at the surface, where species diffusion balances catalytic production for a nonablating wall and a self-consistent diffusion model enforces total mixture diffusion flux conservation. The noncatalytic wall boundary condition enforces zero catalytic production for each species, which implies that diffusion flux for each will be zero.