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

Abstract

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: D = 50 mm) varies based on the equation of motion. First, the dependence of rotor performance on the gap distance (gap) 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 gap/D = 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 gap/D = 2.0. For the first time, this study demonstrates the phase synchronization of two rotors via numerical simulation.

Wind Tunnel Experiments on Interaction between Two Closely Spaced Vertical-Axis Wind Turbines in Side-by-Side Arrangement

“…Recently, Hara et al [5] in our research group conducted a 2-D numerical analysis on the dynamic interaction between two closely spaced VAWTs, where changes in the rotational speed of each rotor could occur as a result of both the interaction between the two rotors and the interaction between each rotor and its surrounding fluid flow. The simulation produced the key results: (1) two closely arranged VAWTs enhanced the power output in the order of CD > CO > CU, and (2) the CO with a gap equal to the rotor radius (0.5D) is most effective with a bidirectional wind.…”

Effect of turbulence on the performance of a pair of vertical-axis wind turbines

“…These studies performed field measurements to study this interaction between paired VAWTs [10]. The power enhancement has been proved numerically [11][12][13]. Moreover, wind tunnel experiments have validated the numerical predictions of an increase in power coefficient for a pair of H-Darrieus VAWTs [14].…”

“…The black frames on the figures indicate the position of the rotors. By examining these two Figures (12,13), the effect of turbulence is less pronounced in the wake shape; a high turbulence intensity leads to a small reduction in the velocity deficit. Furthermore, at y/D = 0, an acceleration region is observable.…”

Numerical Analysis and Parameter Optimization of J-Shaped Blade on Offshore Vertical Axis Wind Turbine

“…When TSR ∈ [2.5, 4], wind energy capture firstly increases and then decreases. J-blade offshore wind turbine and symmetrical airfoil offshore wind turbine have better wind energy utilization rate when TSR ∈ [2.5, 3.5] and TSR ∈ [3,4], respectively. In addition, the greater the distance between the upper surface and the leading edge along the chord length of the wind generator, the higher the wind energy utilization rate is when TSR ∈ [2.5, 3.5], but lower than that of the symmetrical airfoil wind generator.…”

“…Global warming and rising sea levels have made the search for renewable energy more urgent [1]. Europe is rich in wind energy, among several common renewable energy sources; it has been a good renewable energy source and is now one of the fastest growing renewable energy sources in the world [2,3]. Offshore wind turbines can be divided into two categories: offshore horizontal axis wind turbine (HAWT) and offshore vertical axis wind turbine (VAWT).…”