Numerical Analysis of the Dynamic Interaction between Two Closely Spaced Vertical-Axis Wind Turbines

• Main Authors: Yutaka Hara, Yoshifumi Jodai, Tomoyuki Okinaga, Masaru Furukawa
• Format: Article
• Language: English
• Published: MDPI AG 2021-04-01
• Series: Energies
• Subjects: wind energy; vertical-axis wind turbine; computational fluid dynamics; dynamic interaction; closely spaced arrangements; phase synchronization
• Online Access: https://www.mdpi.com/1996-1073/14/8/2286

To investigate the optimum layouts of small vertical-axis wind turbines, a two-dimensional analysis of dynamic fluid body interaction is performed via computational fluid dynamics for a rotor pair in various configurations. The rotational speed of each turbine rotor (diameter: <i>D</i> = 50 mm) varies based on the equation of motion. First, the dependence of rotor performance on the gap distance (<i>gap</i>) between two rotors is investigated. For parallel layouts, counter-down (CD) layouts with blades moving downwind in the gap region yield a higher mean power than counter-up (CU) layouts with blades moving upwind in the gap region. CD layouts with <i>gap</i>/<i>D</i> = 0.5–1.0 yield a maximum average power that is 23% higher than that of an isolated single rotor. Assuming isotropic bidirectional wind speed, co-rotating (CO) layouts with the same rotational direction are superior to the combination of CD and CU layouts regardless of the gap distance. For tandem layouts, the inverse-rotation (IR) configuration shows an earlier wake recovery than the CO configuration. For 16-wind-direction layouts, both the IR and CO configurations indicate similar power distribution at <i>gap</i>/<i>D</i> = 2.0. For the first time, this study demonstrates the phase synchronization of two rotors via numerical simulation.