Skin-friction drag reduction using miniature vortex generators

Abstract: Motivated by the substantial drag reduction achieved by plasma-generated streamwise vortices (Cheng et al. 2021), this study explores the feasibility of using an array of miniature vortex generators (MVGs) to reduce skin friction in turbulence boundary layers (TBL). A total of 486 MVG arrays are examined, varying in MVG shape, height, induced angle, and transverse spacing. Skin friction is measured using an air-bearing floating element (FE) force balance. For the first time experimentally, it is found that an array of simple triangular MVGs can achieve a drag reduction (DR) of up to 4.3% at a friction Reynolds number of Re? = 5500. This DR shows a strong dependence on MVG height, induced angle, and transverse spacing. The DR mechanism is also discussed based on flow visualization and particle image velocimetry (PIV) data. Keywords: drag reduction, vortex generators, turbulent boundary layers