Far field flow simulation of contra-rotating H-Darrieus vertical axis wind turbine

This report presents a three-dimensional Reynolds-Averaged Navier Stokes (RANS) computational fluid dynamics (CFD) investigation of Vertical Axis Wind Turbine (VAWT) with a contra-rotating arrangement. In this study, the length of the simulated domain is set to be relatively long, allowing us to investigate the wake flow generated up to 60 turbine radius (r) downstream of the model. The simulation indicates that the far field flow of the contra-rotating VAWT reaches equilibrium at approximately 40r downstream. Our preliminary analysis shows that at downstream distances between 20r to 30r, the wake recovers between 75% 95% of the free stream velocity, making it an ideal downstream location to place additional VAWTs. Out results also show that the contra-rotating VAWT does not generate a significant flow disturbance beyond 5r in the spanwise direction, suggesting that a row of spanwise arranged contra-rotating VAWTs can be separated by a short distance.