Improving the power production of a vertical axis wind turbine by intelligent closed-loop control of synthetic jet actuators

A major issue of vertical axis wind turbine (VAWT) is the low power coefficient related to the blade dynamic stall. In this study, to improve the power coefficient of a VAWT, piezoelectric synthetic jet actuator arrays were installed within the turbine blades and tuned in a closed-loop fashion. Two geometrical configurations with different jet locations are tested, and the control law, which describes how the synthetic jet amplitude would vary with the rotor phase, was sought automatically by particle swarm optimization. Results show that synthetic jets expelled at the leading edge of the blade are more effective than downstream actuation placed at 12 % chord length. For cases where the energy consumption of actuators is not taken into account, the peak power coefficient of the wind turbine can be improved by about 43 %, with negative net power gain. As a comparison, when the actuator power consumption is taken into account, the net power gain of the VAWT can be increased by 17 % at freestream velocity of 10 m/s. Small but appropriate jets work better than a strong steady jets for improvement of VAWT power production.