Boundary-layer transition experiments in hypersonic flow

Laminar/turbulent boundary-layer transition has a large impact on the viscous coefficient and the heat flux, which are critical for aerodynamic and thermal protection design of hypersonic vehicles. Due to the complexity of hypersonic flow and the numerous factors affecting transition, the mechanism of hypersonic laminar/turbulent boundary-layer transition is still outstanding despite the research upon this issue has been lasting for more than half a century, prohibiting the design of advanced hypersonic vehicles. Ground wind tunnel experiment acts as a significant approach in hypersonic aerodynamic design and is expected to play an important role in the research of hypersonic boundary-layer transition in the future. Based on the hypersonic boundary-layer instability and transition experiments in wind tunnel, the receptivity and linear phases were respectively reviewed according the process of natural transition. Discussions and suggestions were given for experimental study of hypersonic boundary-layer transition.