An LES-Based Investigation of Wake Flow Characteristics of a Shrouded Wind Turbine

In this study, the author investigated the wake characteristics of a shrouded wind turbine and performed a high-resolution large-eddy simulation (LES) investigation using a supercomputer. The turbulent kinetic energy (TKE) of the shrouded wind turbine was significantly greater than that of a conventional wind turbine (non-shrouded wind turbine) in the range of x/D = 0 to 5 (where x is the distance downstream of the hub center and D is the rotor diameter), due to large-scale vortices generated and released from the brim of the shrouded wind turbine and the separated flow from the nacelle. For example, the TKE was 4.4 times larger at x/D = 2. Significant differences were also observed in the wake width. The wake width of the shrouded wind turbine was approximately 2.4 times wider than that of the conventional wind turbine. In contrast, the shrouded and conventional wind turbines exhibited nearly similar behaviors in the far-wake region downstream of x/D = 5. Furthermore, a calculation was performed for the shrouded wind turbine while omitting the brim connected to the diffuser. While flow separation from the diffuser is clearly observed, the numerical results for the shrouded wind turbine without the brim connected to the diffuser showed a flow pattern very similar to that of a conventional wind turbine.