Vertical axis wind turbine performance enhancement using plasma actuators

A small high-solidity vertical axis wind turbine, with dielectric barrier discharge plasma actuators installed on the blade leading-edges, was built and tested in a low-speed wind tunnel. The main objectives were to assess turbine performance enhancements resulting from the control of dynamic flow separation and project the viability of up-scaling the turbine. The actuators employed were configured to control separation only on the upstream half of the turbine azimuth. Turbine power was measured using a specially designed dynamometer that allowed full characterization of its performance. A parametric study showed that actuator duty cycle dependence observed previously on static airfoils was also observed on the turbine. Optimum reduced frequencies, however, showed substantially different dependence and this was traced to the importance of the plasma pulsation frequency relative to the turbine rotational frequency. When considering overall performance improvements, increases in turbine power of up to 38% were measured. Based on the data acquired, up-scaling the turbine by a factor of 5 and 10, the percentage of plasma power required to produce comparable improvements was conservatively estimated at 3.3% and 1.7% respectively. Further work will address phase-locking the plasma pulsation and turbine frequencies, assessing the performance benefits of downwind actuation, employing combined upwind and downwind actuation and measuring the controlled flowfield using particle image velocimetry. (C) 2011 Elsevier Ltd. All rights reserved.