Flow and turbulence conditions in the wake of a H-section in cross flow

Both steady and unsteady wakes of a torsional aeroelastic wind energy converter are examined. The converter consists of a H-section prism with attached pendulums for adjusting the natural frequency of the system. To provide an understanding of the wake characteristics of the device, a particle image velocimetry system was used to measure the mean and fluctuating velocity fields from which various single-point statistics were calculated. For the steady case, wake profiles were obtained at angles of attack from -30° to +30° (at 5° intervals) with the H-section fixed at each angle. In the unsteady case, the H-section was free to vibrate due to flow-structure interaction and a torsional vibration was produced with angles of attack from -30° to +30°. Turbulent wake profiles obtained for the H-section at fixed angles of attack are compared with the oscillating cases and the differences between the various single-point turbulence velocity statistics are discussed. The presented results indicate that the overall dynamic wake deficit for the oscillating case is less than the static wake deficit. Furthermore, the dynamic wake deficit, which is about 20% of U_x is dispersed across the entire section; whereas, the static wake is concentrated around the trailing edge side of the converter.