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On the necessity of considering the hub when examining the induction of a horizontal axis tidal turbine
The induction models developed for wind turbines are not suitable for tidal turbines. The main reason is related to the differences in the ratio of the hub diameter to the rotor diameter, much more important in the case of tidal turbines. Thus, the hub contribution cannot be ignored. Furthermore, the specificities of the flow that impacts the turbine (strong shear) have to be taken into account contrary to a supposedly uniform upstream flow. To address these challenges, a new analytical induction model is proposed that combines both models related to the rotating blade and the hub effect. The effectiveness of the new model is evaluated against a specific experimental database for which a scale horizontal axis tidal turbine is placed in several representative turbulent shear flows. Particle Image Velocimetry measurements are synchronized with turbine thrust measurements to analyze the modifications of the mean velocity fields as a function of the thrust coefficient. The comparison shows that, regardless of the turbine rotational speed and/or the nature of the incoming shear velocity profile, the new model is in good agreement with the experimental results. Therefore, this result is very important for numerical modeling of the flow around the tidal turbines.
Keyword(s)
Induction analytical model, Tidal turbine, Shear flow
Full Text
File | Pages | Size | Access | |
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Author's final draft | 20 | 2 Mo | ||
Publisher's official version | 9 | 2 Mo |