Modeling and validation of a cross flow turbine using free vortex models and an improved 2D lift model

A number of numerical methods have been developed to predict the performance and aerodynamic loads of the Darrieus turbine. Prior work by Reference [1] using blade element methods (BEM) and free vortex methods (FVM) [2] has produced reasonable models that predict the hydrodynamic performance of the Darrieus turbine. The validated models reasonably estimate the performance at low solidities (Nc/R≪1), but lose accuracy at higher solidity ratios. Dynamic stall and flow curvature has been recognized by [2] [3] and [4] to be significant modeling parameters which have limited the accuracy of prior models. The current numerical model extends the predictions of the FVM model to a higher solidity ratio range. An improved model is presented for the condition of high angles of attack and for dynamic stall,. Experimental data on a series of two (Nc/R≈.9) and four (Nc/R≈1.8) blade configurations are presented as validation of the modified analytical vortex model.