Effective Distance for Vortex Generators in High Subsonic Flows

Vortex generators (VGs) are a passive method by which to alleviate boundary layer separation (BLS). The device-induced streamwise vortices propagate downstream. There is then lift-off from the surface and the vortex decays. The effectiveness of VGs depends on their geometrical configuration, spacing, and flow characteristics. In a high-speed flow regime, the VGs must be properly positioned upstream of the BLS region. Measurements using discrete pressure taps and pressure-sensitive paint (PSP) show that there is an increase in the upstream surface pressure and the downstream favorable pressure gradient. The effective distance for a flat plate in the presence of three VG configurations is determined, as is the height of the device (conventional and micro VGs).