Identifying and Mitigating Hub-Induced Power Losses in Ducted Wind Turbine

This numerical study investigates the impact of hub aerodynamics on the power output of a ducted wind turbine (DWT). An axisymmetric hub geometry was added to an actuator disc Reynolds-averaged Navier-Stokes simulation performed using ANSYS Fluent. These results were compared to actuator disk simulations with no hub to quantify the difference in power output. Separated flow was observed to initiate at the intersection of the hub surface and the rotor which reduced the power output. The total power coefficient, CP,total, reduced by 5.5% due to the separation around the hub. To mitigate this a gap was created between the rotor and the inner radius of the actuator disk. A parameter study investigated the influence of hub gap thickness on power output. The gap created a small jet of flow along the hub surface which significantly reduced the flow separation region. The hub gap recovered 5.1% of the power loss, reducing the total loss to 0.4% compared to the case with an actuator disc and no hub. A sensitivity analysis indicated that hub length and diameter had a negligible effect on power generation, highlighting the hub gap as the key factor in minimizing losses.