Abstract
With the increasing demand for wind energy, the vertical axis wind turbine (VAWT) is attracting more and more attention. In order to design the VAWT array for better performance, the VAWT wake model needs to reflect the wake characteristics well. Based on the asymmetric wake characteristic, a new VAWT wake model is proposed in this paper, which is a combination of two semi Gaussian functions with different deviations, and can be called the “double semi Gaussian functions wake model”. The model is simple and has only four parameters (mean, amplitude, left deviation and right deviation). Compared with the traditional Gaussian and Top-hat model, this model can better reflect the asymmetric characteristic of the VAWT wake. In particular, it can describe the behavior of wake merging in the case of counter-rotating twin turbines. Based on this wake model, the velocity field of VAWT array can be reproduced accurately. The goal function is mainly based on the performance of a basic array unit, and it can ensure the rapidity of the optimization process. The optimal arrangements under two different criteria are analyzed. Moreover, the truncation ratio is introduced to ensure that the downstream turbine works at the rated condition, and the optimal arrangements under different truncation ratios are analyzed. In this paper, the proposed wake model provides a good choice for the preliminary design of the VAWT array, and some relevant suggestions on the array arrangement have been put forward.
Highlights
There is huge potential in offshore wind energy, and the number of wind turbines has grown rapidly in recent years [1]
This model is useful in both horizontal axis wind turbine (HAWT) wake and vertical axis wind turbine (VAWT) wake, and the velocity profiles at different cross sections can be fitted into the Gaussian function
Top-hat it canthe better reflect the asymmetric characteristics of theGaussian
Summary
There is huge potential in offshore wind energy, and the number of wind turbines has grown rapidly in recent years [1]. This model is useful in both HAWT wake and VAWT wake, and the velocity profiles at different cross sections can be fitted into the Gaussian function This model can be used to prove the self-similarity of wake field, but it cannot reflect the asymmetry of velocity distribution in some cases. The “double semi Gaussian functions wake model” is proposed, which can better reflect the asymmetry of velocity distribution and deflection characteristic of the VAWT wake. Eng. 2021, 9, 820 the optimal arrangements under different truncation ratios are analyzed
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