Secondary Instabilities of Gertler Vortices in High-Speed Boundary Layers

Abstract

This thesis first reveals the mechanism of Gertler instabilities and thenedemonstrates how transitions at hypersonic flows can be effectively controlled (either promoted or suppressed) with Gertler or Klebanoff modes. It focuses on understanding and controlling flow transitions from mild laminar to fully turbulent flows at high speedseeaspects that have become crucial at the dawn of an incredible era, in which hypersonic vehicles are becoming available. Once this occurs, it will be possible to travel from Beijing to Los Angeles within just 2 hours, and we will all live in a genuinely global villageeeand not just virtually, but physically. Gertler instabilities have often been used to promote flow transition in hypersonic vehicles. However, how Gertler instabilities are excited and how they evolve in hypersonic flows are questions that have yet to be answered. ;