Bulding a robust CFD model using the Taguchi method for the simulation of dynamic passive self-starting of vertical axis wind turbines

Accurately modelling the self-starting of vertical-axis wind turbines (VAWTs) requires careful selection and tests of various computational model parameters which is a tedious task. This study applies the Taguchi Design of Experiments (TDE) to evaluate the influence of key numerical parameters such as freestream turbulence intensity, blade boundary layer mesh, time step size, average computational cell size, inner iterations within each time step, etc. The Taguchi study indicated that the time step size and mesh refinement within the rotating domain, particularly in the blade's boundary layer regions, were the most critical factors in the prediction of the self-starting process. Based on the Taguchi analysis, followed by a more detailed sensitivity analysis of these most critical factors on the accuracy of the CFD simulations, a robust CFD approach was successfully developed in order to correctly simulate the dynamic passive self-starting process of a VAWT. The simulation results of the robust model were found to compare well with the experimental measurements. The influence of the computational model settings on the predicted aerodynamics that are critical to the self-starting of the turbine were discussed. Finally, some practical guidelines were provided for building a robust CFD model for self-starting simulations of the VAWT applications.