Miniature Vortex Generators for Flow Control in Falkner–Skan Boundary Layers

Abstract

Vortex generators with heights comparable to displacement thickness are an effective means of producing persistent mean-flow streaks in laminar boundary layers. Inducing streaky base flows can suppress the growth of unsteady disturbances that would otherwise incite laminar-to-turbulent transition. Previous experimental and numerical works demonstrated the versatility of these miniature vortex generators in zero-pressure-gradient boundary layers. In this work, mean-flow disturbances developing from miniature vortex generators in adverse and favorable pressure-gradient boundary layers are measured systemically to assess the possibility of extending miniature vortex generator-based flow control to these scenarios. Boundary-layer streak amplitudes are measured across a range of Falkner–Skan values, and an empirical scaling is found based on existing results. The effect of streaks on transition in an adverse pressure-gradient boundary layer is also tested, and moderate increases to laminar flow extents are observed.