Modeling and validation of a cross flow turbine using free vortex model and a modified dynamic stall model

This work details the implementation of a modified Beddoes Leishman model into a Free Vortex Method (FVM) to predict the performance of Darrieus turbines. The model uses Sheng's consideration of the reduced pitch rate influence on the dynamic loads over the foil and revised Kirchhoff flow equations to calculate lift and drag at extended ranges of angles of attack. A simple consideration of the Reynolds number cyclic variation on the blades characteristic of the Darrieus turbines is also implemented. Comparison with published and experimental data at a range of chord to radius ratio shows good agreement.