Direct numerical simulation of a reacting turbulent channel flow with thermochemical ablation

Abstract

This study presents the results obtained by performing a set of direct numerical simulations (DNS) of periodic channel flows over an isothermal surface subjected to thermochemical ablation. A specific boundary condition to handle the surface ablation is developed and allows to represent any kind of ablation scheme. By nature, the periodic channel flow configuration is statically unsteady when ablation occurs, which requires a particular attention when investigating flow statistics. An ensemble average over several flow realizations is then employed to generate converged statistics. Hence, this procedure allows to investigate different features of the flow when focusing on species/momentum/energy/atomic conservation. The analysis reveals that the flow can be considered at chemical equilibrium under the conditions investigated. Moreover, the convective effect introduced by the Stephan velocity at ablative surface appears to have no influence on momentum conservation whereas it strongly participates in the surface cooling effect. Finally, an atomic mass conservation equation of the Shvab-Zel’dovich type is formulated, and highlights passive scalar such as the conservation mechanism of atomic elements.

Keywords:

• turbulent boundary layer
• reacting compressible flow
• ablation

Acknowledgements

The authors gratefully acknowledge the CINES for the access to supercomputer facilities, and want to thank the support and expertise of Snecma Propulsion Solide.