This paper establishes a simplified model of the bladeless wind turbine and derives the formula for its power generation efficiency. Numerical simulations were conducted using computational fluid dynamics software Fluent and user-defined functions (UDF), studying the vortex-induced vibration characteristics and power generation efficiency of single and dual degree-of-freedom bladeless wind turbines under different reduced wind speeds. The study shows that the difference in the degrees of freedom of the wind turbine significantly affects its vibration response, aerodynamic characteristics, and power generation efficiency. The vibration amplitude initially increases and then decreases as the reduced wind speed increases, remaining stable in certain wind speed ranges. The vibration trajectory of the dual degree-of-freedom wind turbine at reduced wind speeds primarily forms a figure-eight pattern, exhibiting multi-frequency vibrations when the wind speed approaches the natural frequency, with the trajectory becoming chaotic. The power generation efficiency follows a trend of increasing first and then decreasing with the reduced wind speed, with the efficiency of the dual degree-of-freedom wind turbine being higher than that of the single degree-of-freedom wind turbine. At a reduced wind speed of Ur = 2.4, the maximum power generation efficiency of the single degree-of-freedom wind turbine is 25.19%; at Ur = 3.4, the maximum power generation efficiency of the dual degree-of-freedom wind turbine is 57.14%. Power generation efficiency is influenced by the combined effects of incoming wind speed, vibration velocity, and lift-drag coefficients. With changes in degrees of freedom and reduced wind speeds, the wake vortex shedding patterns of the wind turbine also vary. The vortex shedding patterns of the three-dimensional bladeless wind turbine at different heights in the span direction are similar to those of the two-dimensional wind turbine, but due to smaller vortices in the surrounding flow field, the energy loss is higher, leading to a slightly lower power generation efficiency compared to the two-dimensional bladeless wind turbine.
Key words
Bladeless wind turbine /
Vortex-induced vibration ;Degree of freedom /
Power generation /
Reduced wind speed
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