Noncatalytic and Finite Catalytic Heating Models for Atmospheric Re-entry Codes

The total wall heat flux is one of the key quantities in the evaluation of the ground risk associated to debris atmospheric entry. The computed heat flux assuming catalytic wall or thermochemical equilibrium gas can be twice as large as the non-catalytic wall heat flux, leading to an underestimation of the ground risk. However, most of the models proposed in open literature allow computing stagnation point heat flux for thermochemical equilibrium air gas or chemical nonequilibrium air gas with catalytic walls only, or requires many local quantities that are not yet accessible for engineering atmospheric codes. For these reasons, ONERA developed and successfully validated new analytical models to compute the total heat flux received by the wall assuming any inflow gas state as well as finite-catalytic and non-catalytic wall material properties. These new models have been developed from a large in-house CFD database built-up with the ONERA Navier-Stokes code for various flow conditions (altitude from 70 to 20 km, velocity from 8 to 1 km/s) including different thermochemical air flow assumptions in the shock layer (perfect gas, thermochemical equilibrium and nonequilibrium real gas), effects of the nose radius (from 0.01 m to 1 m) and wall temperature (from 300 K to 2000 K). The present paper proposes an overview of the current research with a focus on the new models developed and their application relevant to on the aerothermodynamic study of the atmospheric entry of a launcher tank. A specific attention is given to the influence of the wall catalycity on the thermal degradation of such debris.