A Low-Order Model for Offshore Floating Vertical Axis Wind Turbine Aerodynamics

Vertical-axis wind turbines (VAWTs) are an attractive economical solution for a deep offshore floating application with their inherent desirable design characteristics. A low-order model is described in this paper that can be utilized for the aerodynamic modeling of these turbines. The cascade model is employed and has been coupled with a dynamic stall model to account for unsteady aerodynamic effects. To provide enhanced numerical efficiency and stability, an iterative time-advancement scheme with an adaptive under-relaxation has been integrated into the developed model. The model's predictive accuracy has been assessed against applicable experimental data in simulating a VAWT's aerodynamics at high Reynolds numbers. A quantitative comparative study shows that the model produced an average normalized root mean square error of 0.106 and 0.288 for the VAWT's normal and tangential force coefficients, respectively. It has been established also that the model's computational requirement is reasonably low and suitable for the industrial design of offshore floating VAWTs.