Computational study of the effect of building height on the performance of roof-mounted VAWT

The power of a Vertical Axis Wind Turbine (VAWT) placed at the frontal corner of a roof-top of a building is significantly higher compared to the same turbine in a uniform wind without a surrounding building. Due to the importance of this configuration's benefits, it is crucial to study its effect for different building heights. To investigate the impact of building height on the power performance of VAWTs, three buildings with heights of 30.48 m (100 ft), 60.96 m (200 ft), and 91.44 m (300 ft) are considered. A two-blade Darrieus-type VAWT is placed on the roof-top, with the wind flow directed straight towards the corner of the building. Computational Fluid Dynamics (CFD) is utilized to simulate the entire flow over the building and the rotating turbine. Different atmospheric boundary wind velocity profiles are considered. Firstly, the same velocity profile is applied to all three buildings, with taller buildings experiencing higher velocities. Secondly, three distinct velocity profiles are used over the buildings, ensuring that the wind velocity at the middle of the turbine for each case remains at 9.3 m/s. The results demonstrate that placing the VAWT on the roof-top of a 30.48 m (100 ft) building increases the maximum Power Coefficient (CP) by 36% compared to the turbine operating in a uniform flow. Moreover, in the case of one velocity profile applied to buildings with different heights, it was observed that the maximum CP increased by 84% for a building with a height of 91.44 m compared to the turbine operating in uniform flow. On the other hand, in the second scenario with three different velocity profiles over the buildings, it was found that the maximum CP increased by 18% and 22% when the turbine was placed in the 60.96 m and 91.44 m buildings, respectively, compared to the 30.48 m building.