Wind-Tunnel Experiments on the Interactions among a Pair/Trio of Closely Spaced Vertical-Axis Wind Turbines

• Published in: Energies (Basel) Vol. 16; no. 3; p. 1088
• Main Authors: Jodai, Yoshifumi, Hara, Yutaka
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 01.01.2023
• Subjects: Aerodynamics; Air-turbines; Analysis; closely spaced arrangement; Computational fluid dynamics; Computer applications; Configurations; Experiments; Flow visualization; Fluid dynamics; Fluid flow; Hydrodynamics; pair of turbines; Reynolds number; Rotation; Rotors; Simulation; trio of turbines; Tunnels; Turbines; Velocity; Velocity distribution; Vertical axis wind turbines; vertical-axis wind turbine; Wind direction; Wind farms; Wind power; Wind speed; Wind tunnel testing; Wind tunnels; wind-direction dependence; wind-tunnel experiment
• ISSN: 1996-1073; 1996-1073
• DOI: 10.3390/en16031088

To elucidate the wind-direction dependence of the rotor performance in closely spaced vertical-axis wind turbines, wind-tunnel experiments were performed at a uniform wind velocity. In the experiments, a pair/trio of three-dimensional printed model turbines with a diameter of D = 50 mm was used. The experiments were performed systematically by applying incremental adjustments to the rotor gap g and rotational direction of each rotor and by changing the wind direction. For tandem layouts, the rotational speed of the downwind rotor is 75–80% that of an isolated rotor, even at g/D = 10. For the average rotational speed of the rotor pair, an origin-symmetrical and a line-symmetrical distribution are observed in the co-rotating and inverse-rotating configurations, respectively, thereby demonstrating the wind-direction dependence for the rotor pair. The inverse-rotating trio configuration yields a higher average rotational speed than the co-rotating trio configuration for any rotor spacing under the ideal bidirectional wind conditions. The maximum average rotational speed should be obtained for a wind direction of θ = 0° in the inverse-rotating trio configuration. The wind-direction dependence of the rotational speeds of the three turbines was explained via flow visualization using a smoke-wire method and velocity field study using two-dimensional computational fluid dynamics.