Numerical Investigation of Hypersonic Boundary-Layer Transition for an Ogive Geometry

Numerical investigations were carried out for an ogive geometry with a blunted nose-tip for the flow conditions of the hypersonic wind tunnel (H2K) experiments of the German Aerospace Center (DLR) at Mach 5.3 and Mach 7. Linear Stability Theory (LST) was employed to analyze the primary instability regime. The LST results indicated amplification of both first and second mode waves. Specifically, second mode waves exhibited higher growth rates than first mode waves for both Mach numbers, while the N-factors were larger for first mode waves at M = 5.3. Based on the LST findings, the feasibility of various “controlled” transition scenarios was explored, with particular focus on first mode oblique breakdown. Simulation results for both Mach numbers demonstrated progression to the late nonlinear stages and an advancement of the boundary-layer toward fully developed turbulent flow. The forcing amplitudes for oblique first mode waves for the “controlled” transition DNS were determined to approximately align the transition onset in the simulations the with experimental transition onset locations. These investigations suggest that a first mode-dominated oblique breakdown may be a viable nonlinear mechanism for transition for the investigated geometry and wind tunnel conditions.