Investigation of power performance and wake on a straight-bladed vertical axis wind turbine with field experiments

This paper investigates the power performance and wake characteristics of a straight-bladed Vertical Axis Wind Turbine (VAWT) with field experiments. In order to observe the aerodynamic forces characteristics, the power performances measured by a torque meter are compared between wind tunnel and field experiments. The values of reference wind and wake velocities are measured through three cup type anemometers and ultrasonic anemometers. As a result, it is clarified that field experiment result of power coefficient shows higher value than that of wind tunnel experiment at low tip speed ratio in the case of high turbulence intensity. Furthermore, the turbulence intensity has an inhibitory effect on power performance at optimal and high tip speed ratios. The maximum velocity deficit is in the position of -0.2 < y/D < 0. Meanwhile, the recovery process in the velocity deficit region is asymmetric. The predictions of wake velocity distributions in different inflow velocities are also investigated with Gaussian function model. It is estimated that wake velocities recover near the positions of x/D = 3.3 and 4.5 in the cases of U-ref = 5.0 and 9.0 m/s. The results have a guiding significance for comprehending the development process of straight-bladed VAWTs. (C) 2017 Elsevier Ltd. All rights reserved.