Infrared thermography investigation of transitional flow over isolated roughness at high speed
Q. Ye (TU Delft - Aerodynamics)
Ferry Schrijer (TU Delft - Aerodynamics)
Fulvio Scarano (TU Delft - Flow Physics and Technology)
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Abstract
The transitional flow features over and downstream of isolated roughness elements in hypersonic flow are investigated by means of infrared thermography. The local heat flux distribution in the wake of the roughness element reveals the footprint of multiple streamwise counter-rotating vortex pairs. The formation of a turbulent wedge with the spanwise spreading of the wake in the downstream region indicates the early stage of transition and breakdown to turbulence. The onset location of transition is predicted by detecting the origin of the turbulent wedge. Strong dependence of the transition process on the roughness geometry is observed, with significant variations of the lateral spreading rate in the turbulent wedge. Instead, for the present flow conditions negligible variations are associated to changes in Reh