Sensitivity of Reacting Hypersonic Boundary Layers to n-periodic Surface Roughness

Successful design of aerospace missions requires accurate modelling of the physical phenomena in a hypersonic boundary layer. The behaviour of hypersonic boundary layers is strongly influenced by finite-rate thermochemical effects. These effects can be captured by including finite-rate thermochemistry models in computational tools. Such models are typically highly parametrised, introducing non-equilibrium features into the flow that generate significant uncertainty, which reflects on the output quantities of interest. The way such phenomena interact with solid boundaries and roughness is fundamentally unknown and the additional uncertainty is unquantifiable. In the present work, we propose the investigation of the linear response of n-periodic roughness arrays using an efficient mathematical framework. We extend an existing computational tool to investigate the effect of roughness, including real-gas and finite-rate chemistry effects by coupling with the Mutation++ library. The proposed framework allows to study efficiently and in parallel the linear flow response and wake synchronisation without the restricting idealised periodicity constraint. The results are extracted from reduced-order geometries using automatic linearisation tools. This framework can be potentially combined with sensitivity analysis tools to identify critical roughness configurations. In this paper, we provide the necessary background and present preliminary results for canonical flat plate hypersonic boundary layers.