A stereoscopic PIV study of the effect of rime ice on the vortex structures in the wake of a wind turbine

The present study experimentally investigated the effect of simulated rime ice on the rotor blades on the helical vortex structures in the wake of a horizontal axis wind turbine by using the Stereoscopic Particle Image Velocimetry (Stereo-PIV) technique. During the experiment, both “free-run” and “phase-locked” Stereo-PIV measurements were carried out and the 3-D trajectories of the tip and root vortex structures in the wake of the wind turbine models were reconstructed. The “free-run” results showed that the simulated rime ice could apparently affect the distributions of velocity, Reynolds stress, and turbulent kinetic energy in the wake of the wind turbine. Besides, the “phase-locked” results indicated that the presence of simulated rime ice not only resulted in different gaps between the helical tip and root vortex tubes, but reduced the vortex core vorticity of tip vortices at different phase angles as well.