Application of Richardson extrapolation method to the CFD simulation of vertical-axis wind turbines and analysis of the flow field

Application of Richardson extrapolation method to the CFD simulation of vertical-axis wind turbines and analysis of the flow field

Blog Article

There is still discrepancy regarding the verification of CFD U-RANS simulations of vertical-axis wind turbines (VAWTs).In this work, the applicability of the Richardson extrapolation method to assess mesh acupatch convergence is studied for several points in the power curve of a VAWT.A 2D domain of the rotor is simulated with three different meshes, monitoring the turbine power coefficient as the convergence parameter.

This method proves to be a straightforward procedure to assess convergence of VAWT simulations.Guidelines regarding the required mesh and temporal discretization levels are provided.Once the simulations are validated, the flow field at three characteristic tip-speed remtavares.com ratio values (2.

5 - low, 4 - nominal and 5 - high) is analyzed, studying pressure, velocity, turbulent kinetic energy and vorticity fields.The results have revealed two main vortex shedding mechanisms, blade- and rotor-related.Vortex convection develops differently depending on the rotor zone (upwind, downwind, windward or leeward).

Finally, insight into the loss of performance at off-design conditions is provided.Vortex shedding phenomena at the low tip-speed ratio explains the loss of performance of the turbine, whereas at the high tip-speed ratio, this performance loss may be ascribed to viscous effects and the rapid interaction between successive blade passings.