Study on Aerodynamic Forces of Straight-bladed Vertical Axis Wind Turbine by using Pressure Measurement

Abstract

This research aimed to study aerodynamic forces for a vertical axis wind turbine (VAWT). Surface pressure distributions on the blade surface were detected using 32 pressure sensors for the rotating condition in the wind tunnel. All experiments were conducted for the optimum tip speed ratio. The numerical prediction by using the classical Double-Multiple Stream tube (DMS) Model was used to compare results with experiment data. The test wind turbine has a two-bladed rotor made from NACA0021 airfoil with a radius of 1,000 mm. The maximum power coefficient of the test wind turbine is 0.22 at the tip speed ratio of 2.37. As a result, it is clarified that the cyclic motion of the wind blade induces variations of pressure distribution around the blade section surface. The normal and tangential coefficients take a maximum value in the upstream region where the high angle of attack. While lift and drag coefficients decrease with decreased angle of attack in the upstream region due to stall phenomenon.