Wind tunnel experiments for innovative pitch regulated blade of horizontal axis wind turbine

•Innovative partial folding blade model for power control is made.•Wind tunnel experiments are conducted to validate the effectiveness of the blade.•Blade energy conversion efficiency and available wind energy reduction affect power.•Blade highest power coefficient can be reduced by up to 82.8% by fold control.•Constant power output and fold angle control rule are obtained with tested blade.

In current study, innovative pitch regulated blade model with folding outer blade section to control power output was made. A small wind turbine rotor with three innovative blades was tested in a low speed wind tunnel to validate the blade effectiveness. The main objective of current study is to investigate this blade performance in limiting power growth in high wind speed and to discuss its mechanism to control power. All the experiment data are inclusive of wind tunnel blockage correction and blade performance is assessed in terms of power output and power coefficient. It is found that when the outer blade section is folded, decrease of both blade energy conversion efficiency and wind energy contained in the airflow that passes through the rotor leads to power output reduction. The highest power coefficient of tested blade is 0.23 and can be reduced by the maximum of 82.8% through folding control. A constant power output in high wind speed is achieved with the tested blade and corresponding fold angle control rule is acquired.