Investigation of wake effects on a Horizontal Axis Wind Turbine in field experiments (Part I: Horizontal axis direction)

In order to investigate the effects of turbulence intensity and wind shear on the wind turbine wake characteristics, this paper presented the wind velocity distribution of Horizontal Axis Wind Turbine (HAWT) in the horizontal axis direction by field experiments. The test wind turbine had a generator capacity of 30 kW, a rotor diameter of 10.0 m and a hub height of 13.4 m. The reference wind velocity was measured with an ultrasonic anemometer. In the upstream wind measurement mast, the three-cup type anemometers and arrowhead type wind vane were installed. An ultrasonic current meter (SAT-550) which was mounted on the after-stream measuring device equipped which was used for the measurement of the wake at multiple points. Furthermore, the experimental condition of the wake measurement was set at the different inflow velocities and the tip speed ratios. As a result, the maximum velocity deficit in the wake was reduced with the increase of the turbulence intensity. Moreover, as the wind shear index increased, the maximum velocity deficit in the wake was increased. The maximum deficit amount of the non-dimensional wind velocity ratio UNR in the wake increased with the increase of the tip speed ratio.