Theoretical, numerical and experimental study of hypersonic boundary layer transition: Blunt circular cone

Abstract

• Hypersonic boundary layer transition is studied using various approaches. • Leading edge receptivity is crucial for understanding “transition reversal”. • Centreline and crossflow vortices significantly promote transition on a yawed cone. • The newly proposed C - γ - Re θ transition model works well at various flow conditions. • Valuable transition data is acquired in real flight test for a cone model. This article reviews the hypersonic laminar-turbulent boundary layer transition over a blunt circular cone under support of the National Key Research and Development Program of China (contract No. 2016YFA0401200). Various approaches, including theoretical, numerical, experimental and flight test, are combined to obtain a complete perspective of the transition process as well as some fundamental issues for this kind of flow. The interaction between freestream disturbances and the front shock wave is analysed theoretically, and multiple receptivity routes are unveiled using a sub-zone analysis technique. The entire transition process is captured using high-resolution nano-tracer-based planar laser scattering technique in a quiet windtunnel as well as large-scale high-fidelity direct numerical simulations. Using dynamic mode decomposition, the relationship between the second Mach mode and the low-frequency mode in the late stage of the transition is revealed. The “transition reversal” phenomenon is recovered in two of our conventional windtunnels. The numerical results show that leading-edge receptivity varies significantly for different cone bluntness, which might be responsible for the “transition reversal” phenomenon. For the cone at angles of attack, new instabilities including the leeward centerline vortex instability and the crossflow instability, occur and can significantly promote the transition process. A newly developed C - γ - Re θ transition model can give a good transition front prediction compared to the experimental data. The flight test for a cone model conducted within this project is reviewed, and the correlation between the ground experimental data and the flight data is established.