Study on the Wake Behaviour of Straight-bladed Vertical Axis Wind Turbine by Field Experiments

Abstract

The vertical axis wind turbine has a characteristic that the angle of attack of the blade fluctuates greatly during one revolution, and the separation and reattachment of the blade surface flow are repeated. Due to its characteristics, the wake of the wind turbine has a complicated flow field compared to that of the horizontal axis wind turbine. In this study, we conducted a field experiment to clarify the wake behavior of a vertical axis wind turbine under unsteady natural wind conditions. In the field experiment, the velocity field was measured using multiple ultra-sonic anemometers installed downstream of the test wind turbine, and the flow field inside wake of wind turbine and the wake influence range of the wind turbine were investigated. In addition, the discrete data obtained in the field experiment was fitted with a Gaussian function and wake models were created to quantitatively evaluate the wake influence range of the wind turbine. As a result, the tendency of the wake behaviour of the vertical axis wind turbine in natural wind was able to be grasped. Furthermore, the wake influence range was estimated by approximating the change of each parameter value of the wake models by linear functions.