The flow in the induction and entrance regions of lab‐scale wind farms

Abstract

With the increasing demand for wind energy, it is important to be able to understand and predict the available wind resources. To that end, the present wind tunnel study addresses the flow in the induction and entrance region of wind farms through particle image velocimetry, with focus on differences between actuator disks and two‐bladed rotating wind turbine models. Both staggered and aligned farm layouts are examined for three different incoming wind directions. For each layout, 69 disks or turbines are used, and the field of view ranges from 12 rotor diameters upstream of the farms to 8 diameters downstream of the first row. The results show that the induction, or blockage effect, is higher for the disks, even though the thrust (or drag) coefficient is the same. In contrast, the wake is stronger downstream of the turbines. The orientation and layout of the farm do not have a major impact on the results. Modal decomposition of the flow shows that the flow structure similarity between the disk and turbines improves downstream of the second row of wake generating objects, indicating that the substitution of wind turbines by actuator disks is more appropriate for wind farms than for the investigation of single wakes.

Sustainable New Technology for the Improvement of Metallic Materials for Future Energy Applications

“…The highest demand and largest source of renewable energy in the global market is currently onshore and offshore wind [99]. Wind energy is based on the conversion of kinetic energy into rotational energy, which is then converted into electrical energy by means of a shaft [100].…”

A mesoscale study of the occurrence and impact of wind farm blockage

“…This is usually experienced as a decrease in the approaching wind speed due to the presence of the wind farm, resulting into a reduction of the Annual Energy Production (AEP) of the farm under consideration. Early wind-tunnel studies 1,2,3 and numerical simulations 1,4,5,6 confirmed that the presence of wind turbines is perceived by the approaching wind that, consequently, tries to avoid the farm by deflecting upward or on the sides, decreasing the intensity of the wind that enters the wind farm and that can be exploited to produce power. The industrial wind community needed a tool to assess this loss and a number of theoretical corrections were proposed 7,8 to assess wind-farm blockage for generic layouts: some of these methods have become standard assessment tools implemented in wind analysis software.…”