Abstract
In this study, a numerical model was developed to study the effects of aerodynamic interactions between a pair of counter-rotating vertical axis wind turbines (VAWTs) in close proximity. In this model, the rotor rotation is not prescribed as a constant as in most other studies, but is determined by the moment of inertia and the total torque of the rotor, including the aerodynamic torque, generator torque, and a torque representing friction. This model enables study of the behavior of the rotor under an arbitrary ambient wind profile. The model was applied to an isolated rotor with five straight J-blades and pairs of identical rotors placed in close proximity. Compared with an isolated rotor, the aerodynamic interactions between the pair of rotors enhance the aerodynamic torques on the rotors and significantly increase the turbine power output on a per unit basis. The enhancement in turbine power output due to aerodynamic enhancement decreases with the distance between the pair of rotors.
Highlights
For the past few decades, development of wind turbine technology has contributed to great growth of wind energy applications
Where I is the moment of inertia of the rotor, Twind is the aerodynamic torque acting on all the blades, Tgenerator is electric load from the generator, which is set as Tgenerator = aω 2 where a is a constant, and Tfriction is a small value constant representing the mechanical friction on the rotor
A numerical model was developed to study the effects of aerodynamic interaction
Summary
For the past few decades, development of wind turbine technology has contributed to great growth of wind energy applications. Modern wind farms comprised of HAWT require significant land resources to separate each wind turbine from the adjacent turbine wakes. They are omni-directional; they do not require complex yaw-control to point into the wind They could utilize long blades; providing a large swept area on a small footprint. The Darrieus type VAWT, on the other hand, is a wind turbine driven by lift force [2]. Unlike the Savonius type, due to the small lift forces on the blades blades at at low low rotational rotational speeds, speeds, sometimes the torque is insufficient to overcome the friction at startup, especially for low-solidity. J-shaped blade uses both lift and drag forces to drive the leading edge portion of the pressure-side surface.
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