Experimental investigation and CFD modeling on rooftop vertical axis wind turbine for sustainable residential buildings: development of core design optimization and advanced performance analysis

Vertical Axis Wind Turbines (VAWTs) offer a viable sustainable alternative, with improved efficiency and highly aerodynamic characteristics. Evaluating the performance of wind turbines is critical for their successful integration into urban distributed clean power systems. This study presents comprehensive design optimization, experimental prototyping, and thermo-fluid performance analyses of a VAWT facilitated for green residential buildings. The research commenced with a two-year wind resources assessment at two candidate rooftops building in Dhahran, Saudi Arabia. Initially, a preliminary design is conducted using blade element momentum method to optimize the thermo-fluid performance and structural efficiency of the VAWT blades. The airfoil selection is then validated through both static and dynamic wind tunnel testing of the NACA 0022 profile at various Reynolds numbers. Furthermore, detailed numerical modeling is then performed using CFD simulations to optimize the rotor geometry in natural convection environment. Lastly, experimental studies on the optimal VAWT design are carried out on both open-jet laboratory testing and rooftop outdoor field. The lab test data showed good alignment with the numerical results, particularly near the peak performance region, thereby also validating the fidelity of CFD model. The results indicated that the optimal design comprised three NACA 0022 blades, with 200 mm chord, 800 mm rotor diameter, and 1000 mm height, respectively. The optimal turbine design achieved a maximum power coefficient of 0.212 in CFD simulations and 0.200 in field tests, respectively. Moreover, a cut-in speed of 2.25 m/s was observed in the lab tests, while the rooftop outdoor field indicated higher starting speeds. Field tests under average wind speeds of 3.75, 5.88, and 8.48 m/s yielded average wind power outputs of 7.82 W, 29.43 W, and 143.02 W, respectively. The findings underscore the necessity of accounting for turbulent wind conditions in real-world sustainable applications and offer a robust and replicable framework for designing VAWTs suitable for rooftop installation in green buildings.