A high drag vortex generator for inhibiting the formation of boundary layer gas flow is mounted in a duct having a strong adverse pressure gradient with high speed gas flow over a primary aerodynamic. The vortex generator includes a mounting for supporting the high drag vortex generator at a spatial interval in the high speed gas flow above the primary aerodynamic surface. The high drag vortex generator is supported from the mounting and extends from the mounting in the high speed gas flow less than the full distance to the primary aerodynamic surface. Each high drag vortex generator includes first and second vanes. The first and second vanes have flow confining components at substantial right angles to one another. The vanes flow confining components deflect fluid flow towards and/or away from the primary aerodynamic surface inhibiting boundary layer formation downstream of the vortex generator.