M.Sc Thesis

M.Sc StudentEidelman Alexander
SubjectDevelopment of a Reciprocal Motion Wind-Energy Generator
DepartmentDepartment of Mechanical Engineering
Supervisor PROF. David Greenblatt
Full Thesis textFull thesis text - English Version


This thesis presents a novel method of harvesting wind energy by periodically controlling the separation and attachment of the boundary layer over a finite-span circular cylinder, producing periodic loads on the cylinder and potentially causing its vibration. The control was achieved by DBD plasma actuators mounted on the cylinder and triggered at a wide range of excitation parameters. The concept is intended for energy generation and was demonstrated experimentally on a one and two degree of freedom device, within a continuous blow-down wind tunnel. The two degree of freedom device was designed and manufactured in order to act as platform for all future research with the ability to simulate different flow regimes, actuation techniques and device-load configurations. Sub-critical Reynolds numbers were considered where the typical shedding frequencies are much higher than the system natural frequency and the separation point location is almost fixed. Free release experiments were performed and the natural parameters were obtained, including the structural, flow-related and load-related damping coefficients and natural frequencies. Transient forces were experimentally obtained and a piecewise continuous forcing function was developed for future implementation in a numerical model. Periodic loads on the cylinder, produced significant amplitude vibrations in both lateral (perpendicular to the flow) and longitudinal (parallel to the flow) directions, with a notable tendency towards the lateral vibrations at actuation frequencies close to the system’s natural frequency. Lastly, two types of loads were introduced and the output power was measured and compared to the theoretically obtained values. The power coefficients calculated were relatively small (0.007), but according to several sensitivity checks and model estimations they can be increased by proportionally increasing the system’s size and by introducing other means of actuation.