Low speed wind tunnel design, setup. validation and testing of airfoils in turbulent inflow conditions

Abstract

The present work aims to design and setup a low speed wind tunnel (LSWT) to be constructed at Mondragon Unibertsitatea for aerodynamic performance analysis of airfoils at low Re number. With this purpose, flow field characteristics through the test section are investigated to ensure that the flow quality requirements are accomplished. Once the LSWT is validated, a passive grid is installed upstream of an airfoil model representative of wind turbine blade sections to analyse the effect of free-stream turbulence conditions on the aerodynamic performance. In the second stage, two modelling approaches are developed in the context of grid-generated turbulence. The ability of simple numerical simulations (Reynolds Averaged Navier-Stokes) to capture the large scale properties of the turbulence downstream a passive grid is tested for design purposes of the grid. The study is completed with the development of a new in ow turbulence generation method to be applied within large eddy simulation (LES) for its use in airfoil simulations at low Re number. Finally, it is proposed that the developed method can be combined with the performed detached eddy simulations (DES) of the flow around an airfoil. These simulations represent a promising approach to numerically study the effect of turbulent in flow conditions on airfoil performance, which is one of the main limitations of numerical methods for modelling turbulence.