This paper predicts and analyzes the aerodynamic performance of a Vertical Axis Wind Turbine (VAWT)
with variable amplitude dynamic blade pitching. This study contributes to the physics based understanding
of the dependence of power extracted by the turbine on various design parameters. An aerodynamic
model based on double multiple streamtube theory coupled to an airfoil table lookup based
blade element theory analysis and attached unsteady aerodynamics is used for performance prediction. A
method for calculating virtual camber effect for dynamically pitching blades is proposed and validated.
Inclusion of dynamic virtual camber effect and unsteady aerodynamics are critical for accurate performance
prediction. The parametric study relates performance of VAWT to rotor solidity, blade airfoil and
pitch amplitude. It is concluded that the amplitude of sinusoidal blade pitching must be varied with wind
speed and tip speed ratio to maximize the power extracted from the turbine for wide range of wind
speeds and tip speed ratios. High (about 35) pitch amplitudes work best for tip speed ratios below 0.5
and the pitch amplitude should be reduced to approximately 10 for tip speed ratios greater than 2.0.