Experimental Testing of Wind Turbines Using Wind Tunnels With an Emphasis on Small-Scale Wind Turbines Under Low Reynolds Numbers

Abstract

The future of wind turbine design must include wind tunnel testing to produce high quality, experimental data used for designThese experimental data, both airfoil and overall system performance, can be used to validate and improve the design of the wind turbine blades and systemsCurrently, little experimental testing of wind turbines is performed, with much of the aerodynamic design being accom- plished using computational tools such as PROFIL and XFOILComputational Fluid Dynamics (CFD) prediction is improving and will be an outstanding tool for wind turbine blade design; however; these codes are not robust enough for pre- dicting performance under low Reynolds numbersLittle experimental laboratory verification of CFD codes exists for wind turnines, especially for low-Reynolds numbersTypically wind turbines are designed and built full scaleBecause wind tunnel testing is often field tested to compare with the design predicationsHow- ever, field testing can also be a very expensive processThis chapter will focus on the necessity of experimentally testing wind turbine blades to determine airfoil lift and drag data over typical Reynolds numbers of operation and also the testing of wind turbine systems (blades and generator) to determine overall wind turbine performanceThis type of testing should be accomplished prior to building the full scale machine because a better design can be reached with wind tunnel testing� The Blade Element Momentum Theroy (BEMT) is typically used in the design of small-scale wind turbines and this design method depends heavily on the use of accurate airfoil dataThus, for small-scale wind turbines, quality experimental airfoil data taken at the appropriate Reynolds numbers are necessary for accurate design and prediction of power productionThe data presented are for wind tunnel