Abstract
A comparative analysis of seven commonly-used eddy-viscosity turbulence models for CFD simulations of VAWTs is presented. The models include one- to four-equations, namely the Spalart-Allmaras (SA), RNG k-ε, realizable k-ε, SST k-ω, SST k-ω with an additional intermittency transition model (SSTI), k-kl-ω and transition SST (TSST) k-ω models. In addition, the inviscid modeling is included in the comparison. The evaluation is based on validation with three sets of experiments for three VAWTs with different geometrical characteristics operating in a wide range of operational conditions, from dynamic stall to optimal regime and to highly-rotational flow regime. The focus is on the turbine wake, the turbine power performance, and the blade aerodynamics. High-fidelity incompressible unsteady Reynolds-Averaged Navier-Stokes (URANS) simulations are employed. The extensive analysis reveals high sensitivity of the simulation results to the turbulence model. This is especially the case for the turbine power coefficient CP. The results show that the inviscid, SA, RNG k-ε, realizable k-ε and k-kl-ω models clearly fail in reproducing the aerodynamic performance of VAWTs. Only the SST model variants (SST k-ω, SSTI and TSST) are capable of exhibiting reasonable agreement with all the experimental data sets, where the transitional SST k-ω versions (SSTI and TSST) are recommended as the models of choice especially in the transitional flow regime.
Highlights
Two promising and rather unexploited locations for further wind energy harvesting are deep-water offshore and urban/suburban environments [1]
In order to benefit from the advantages of vertical axis wind turbines (VAWTs) for the aforementioned locations, their aerodynamic performance needs to be further improved
The best-performing turbulence model is selected as the model which provides the best agreement with all the three sets of measurements
Summary
Two promising and rather unexploited locations for further wind energy harvesting are deep-water offshore and urban/suburban environments [1]. Concerning the former, floating wind farms are currently being investigated [2e8]. Vertical axis wind turbines (VAWTs) are highly advantageous over horizontal axis wind turbines (HAWTs) mainly due to their omni-directionality, scalability, less manufacturing/installation/maintenance costs, less noise, higher space efficiency, less shadow flickering, bird/bat safety, and more visual aesthetics [26e29]. In order to benefit from the advantages of VAWTs for the aforementioned locations, their aerodynamic performance needs to be further improved
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