Vortex Generator Induced Flow in a High Re Boundary Layer

C M Velte,J-M Foucaut,C Braud,S Coudert

doi:10.1088/1742-6596/555/1/012102

Abstract

Stereoscopic Particle Image Velocimetry measurements have been conducted in cross-planes behind three different geometries of Vortex Generators (VGs) in a high Reynolds number boundary layer. The VGs have been mounted in a cascade producing counter-rotating vortices and the downstream flow development was examined. Three VG geometries were investigated: rectangular, triangular and cambered. The various VG geometries tested are seen to produce different impacts on the boundary layer flow. Helical symmetry of the generated vortices is confirmed for all investigated VG geometries in this high Reynolds number boundary layer. From the parameters resulting from this analysis, it is observed at the most upstream measurement position that the rectangular and triangular VGs produce vortices of similar size, strength and velocity induction whilst the cambered VGs produce smaller and weaker vortices. Studying the downstream development in the ensemble and spanwise averaged measurements, it is observed that the impact from the rectangular and triangular VGs differs. For the rectangular VGs, self-similarity in the streamwise component was confirmed.

Highlights

Vortex Generators (VGs) are commonly employed on wind turbine blades to transfer high momentum fluid closer to the wall and thereby control separation
Stereoscopic PIV (SPIV) has been applied on vortex generators on a bump in a high Reynolds number boundary layer that would otherwise be on the verge of separation [1]
This parametric study optimized the VGs for the current geometry using hot-film shear-stress probes and the optimal flow was characterized with SPIV

Summary

Introduction

Vortex Generators (VGs) are commonly employed on wind turbine blades to transfer high momentum fluid closer to the wall and thereby control separation. It is of vital importance to better understand the flow generated by these vanes This has been attempted in various works, but few have so far been able to investigate the instantaneous vortex structures due to the lack of available techniques. SPIV has been applied on vortex generators on a bump in a high Reynolds number boundary layer that would otherwise be on the verge of separation [1].

Methods

Results

Conclusion