Characterizing porous disk wakes in different turbulent inflow conditions with higher-order statistics

Abstract

The wakes of a uniform and a non-uniform porous disk exposed to two different turbulent flows are investigated experimentally. The disks are representative of static wind turbine models found in literature. Six wake profiles were collected through hot-wire anemometry between three and 30 diameters downstream of the disks. Both one-point and two-point statistics are studied. The results show that higher freestream turbulence affects the wake of the uniform disk more than that of the non-uniform disk, also changing the wake’s shape and recovery rate. Furthermore, we confirm earlier findings that the turbulence at the centerline in the developed part of the wake is independent of both the design of the wake-generating object and the inflow. Similar to findings in the wake of a wind turbine, a ring of high intermittency is found at the very edge of the wakes of both disks and in both inflow conditions. We identify the existence of this ring over a range of scales. The results show that, even for higher-order two-point statistics, the developed wake of different porous disks qualitatively agrees well with the wake of wind turbine models.