Hypersonic N2 boundary layer flow velocity profile measurements using FLEET

Femtosecond laser electronic excitation tagging (FLEET) velocimetry was used in the boundary layer of an ogivecylinder model in a Mach-6 Ludwieg tube. One-dimensional velocity profiles were extracted from the FLEET signal in laminar boundary layers from pure N-2 flows at unit Reynolds numbers ranging from 3.4 x 10(6)/m to 3.9 x 10(6)/m. The effects of model tip bluntness and the unit Reynolds number on the velocity profiles were investigated. The challenges and strategies of applying FLEET for direct boundary layer velocity measurement are discussed. The potential of utilizing FLEET velocimetry for understanding the dynamics of laminar and turbulent boundary layers in hypersonic flows is demonstrated. (C) 2021 Optical Society of America

Automated summary

This study utilized femtosecond laser electronic excitation tagging (FLEET) velocimetry in the boundary layer of an ogive-cylinder model in a Mach-6 Ludwieg tube, investigating the effects of model tip bluntness and unit Reynolds number on velocity profiles. The potential of FLEET velocimetry for understanding the dynamics of laminar and turbulent boundary layers in hypersonic flows was demonstrated.