Journal of Fundamentals of Renewable Energy and Applications
Open Access
ISSN: 2090-4541
+44 1300 500008
ISSN: 2090-4541
+44 1300 500008
David Greenblatt
Technion ��? Israel Institute of Technology, Israel
Keynote: J Fundam Renewable Energy Appl
Recent demand has driven renewed interest in vertical axis wind turbines (VAWTs) due to their insensitivity to wind direction, proximity of the generator to the ground and low noise levels. A drawback of VAWTs is the dynamic stall their blades experience as they pitch beyond their static stall angle, resulting in power losses and large unsteady loads imposed on the drive train. During the last four years, our research group has made significant progress in controlling VAWT dynamic stall by means of pulsed dielectric barrier discharge (DBD) plasma actuators. We produce plasma pulses at frequencies that correspond to flow instability frequencies, thereby generating blade-spanwise vortices that transfer high momentum fluid to the blade surface. This ameliorates or eliminates dynamic stall. We constructed and tested small double-bladed VAWT with dielectric barrier discharge plasma actuators installed on the upwind blade��?s leading-edges. Introducing the pulses produced a 35% increase in gross turbine power. We complemented this study by performing particle image velocimetry measurements on the blades while subjected to pulsed plasma actuations and observed that the dynamic stall vortex was significantly ameliorated. Recently we have focused on feed-forward and closed-loop flow control and we achieved a remarkable net turbine power increase of more than 10%. Following this, we developed a scheme for switching between inboard and outboard control on the blades, thus facilitating both upwind and downwind dynamic stall control. Our present efforts are aimed at maximizing net turbine power output by means of closed-loop control and field-testing a 2 kilowatt proof-of-concept demonstrator.
David Greenblatt is an Associate Professor at the Technion’s Faculty of Mechanical Engineering. He obtained his PhD from Tel Aviv University in 1999 and since then has held Post-doctoral and teaching positions at NASA, TU Berlin and IIT (Chicago). His research interests focus on energy-related flow control applications, unsteady aerodynamics, active separation control and dynamic stall control. He has than authored or co-authored more than sixty journal papers and book chapters, more than a hundred conference papers and reports, and has been awarded numerous patents. He is the Founder and Director of the Flow Control Laboratory.
Email: davidg@technion.ac.il