Experimental and numerical investigations of transition laminar/turbulent on a capsule model in a hypersonic Ludwieg tube

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Transition laminar/turbulent of the three dimensional boundary layer on the windward side of blunt r-entry capsules with incidence will be investigated experimentally and numerically. The development of the relevant boundary layer instabilities and non-modal distortions will be thoroughly characterized. The numerical simulations are based on a two-dimensional eigenvalue method and extensions to solve the parabolized stability equations. They will also take into account optimal growth of non-modal distortions. The numerical results will be validated by using experimental data from time-resolved pressure measurements, heat transfer measurements and hot-wire measurements inside the bow shock of the capsule. Furthermore, freestream disturbances in the test section will be systematically measured by using different probe shapes and sensors. Well-defined roughness elements will be positioned on the capsule and their effect on the transition process will be documented. This includes single roughness elements and distributed roughness. The project prepares the ground for successful extrapolation of transition analysis to flight conditions in the long term.