Computational modelling of TRIANGULAR sub-boundary-layer vortex generators

¹ Nuclear Engineering and Fluid Mechanics Dep., University of the Basque Country, Nieves Cano 12, 01006 Vitoria-Gasteiz, Araba, Spain
² Department of Mechanical Engineering, University of the Basque Country (UPV/EHU), Nieves Cano, 12, 01006 Vitoria-Gasteiz, Spain
³ Automatic control and System Engineering Dep., University of the Basque Country, Nieves Cano 12, 01006 Vitoria-Gasteiz, Araba, Spain

^* Corresponding author: unai.fernandez@ehu.eus

Abstract

Vortex generators (VGs) are used increasingly more by the wind turbine manufacture industry as flow control devices to improve rotor blade aerodynamic performance. The VG height is usually designed with equal thickness of the local boundary layer at the VG position. Nevertheless, these conventional VGs may produce excess residual drag in some applications. The so-called sub boundary layer VGs can provide enough momentum transfer over a region several times their own height for effective flow-separation control with much lower drag. The main objective is to investigate how well the simulations can reproduce the physics of the flow of the primary vortex generated by a triangular VG mounted on a flat plate with negligible pressure gradient with the angle of attack of the vane to the oncoming flow β= 18. Three different device heights H= 5mm, H1= 6,25mm, H2= 4,16mm have been studied and compared both qualitatively and quantitatively. To that end, computational simulations have been carried out using RANS method and at Reynolds number Re = 2600 based on the boundary layer momentum thickness θ= 2.4 mm at the VG position. The computational results show good agreement with the experimental data available in AVATAR project.