Measurements and Calculations of Aerodynamic Torques for a Vertical Axis Wind Turbine

This report describes measurements of aerodynamic torque on a vertical-axis wind turbine. Accelerometers mounted at the equator of the rotor and a torque meter mounted at the base of the rotor were used to compute the net aerodynamic torque acting on the rotor. Assumptions concerning blade-response symmetry were required to achieve blade torque as a function of rotor position on each half of a revolution for a two-bladed rotor. Results are presented for tip-speed ratios from 2.5 to 8.0 for two turbine rotational speeds. Evidence of dynamic stall is observed at low tip-speed ratios.