High-Torque Oscillating Wind Energy Generator

Abstract

This research investigates a novel concept in small-scale wind-energy generation. Instead of rotating turbine blades, the present concept produces reciprocating motion that is achieved by alternately activating boundary layer control (slot blowing) on opposite sides of a circular cylinder. This is commonly called the Coandă-effect, and here we deploy it periodically on a spring-stabilized vertical cylinder, to produce reciprocating motion. This Co andă-based Re ciprocating (CoRe) system converts wind energy to mechanical work. Compared to wind turbines and windmills, the CoRe system generates higher torque and is therefore well suited to directly driving positive displacement pumps for drip-irrigation or reverse osmosis water desalination. This new approach necessitates the investment of energy in order to extract energy from the wind and therefore a major challenge is to maximize the output/input ratio in order to render the concept viable. Previous preliminary wind tunnel tests conducted on the CoRe system produced gross and net power coefficients of 10% and 3% respectively. However, the blowing slot design has a decisive impact on output power. On the basis of data presented in the literature and our computational analysis, the CoRe system produces significantly greater torque than all types of wind turbines with net power coefficients over 10%.

Improving the oscillating wind turbine model

“…In recent years, the oscillating-rotating type of installation described in article [4] has been experimentally tested on land. The work concept is based on the Coande effect, which uses the reciprocating motion (CoRe) of the turbine blades instead of rotation.…”

Wind Energy Generation by Forced Vortex Shedding

“…More recently, our group developed the so-called Coandă-based Reciprocating (CoRe) system [24] where alternating slot blowing at 0.05 e St  was applied alternately on the sides of a circular cylinder, for the purpose of developing a wind energy device (see Video). This concept is particularly effective as a high-torque device [25] that was demonstrated as a means of driving piston pumps for water desalination [26]. In all of these studies, the periodic active flow control frequency was very close to the system fundamental frequency, but significantly less than the natural shedding frequency, with resulting modest efficiencies 4%.…”