Abstract
The Savonius-type hydraulic turbine, mainly known for its good self-starting properties and simple structure, not only has energy capturing characteristics but also has a certain effect on flow velocity reduction. Aside from ensuring energy capture efficiency, studying the effects of parameters on the flow velocity reduction capacity is of great significance for the protection of mariculture, as it can reduce the damage to cages and fishes. In this study, a computational fluid dynamics method was carried out to investigate the hydrodynamic characteristics and variations in the wake of a turbine. The accuracy of the simulation results was verified by experimental comparison. Firstly, the velocity contours and vectors were studied in detail to reveal the mechanism of the flow velocity reduction effect. Secondly, the velocity attenuation coefficient and relative attenuation length were formulated by the variation rule of the velocity field to evaluate the turbine reduction strength and range. Finally, the power coefficient was considered to predict the performance of a turbine under different tip speed ratios, overlap ratios, blade curvatures, and blade numbers. The results showed that the turbine had an obvious flow velocity reduction effect in the rear “sword”-shaped area, where the velocity field distribution had a certain regularity. In addition, by comprehensively comparing the simulation data, it was found that the respective effect trend of tip speed ratio, blade number, overlap ratio, and curvature on the turbine’s energy capture and flow velocity reduction characteristics was basically the same. Considering the effect of reducing flow velocity, a two-bladed turbine with a blade curvature of 0.8 and an overlap ratio of 0.15 is the optimal configuration.
Highlights
At this stage of rapid social and economic development, the energy crisis and environmental damage caused by traditional fossil resources are becoming increasingly prominent
Based on on the the results reported earlier in this paper, it was found that had an effect on the flow velocity results reported earlier in this paper, it was found that tip speed ratio (TSR) had an effect on the flow velocity reduction thethe properties of energy capturecapture and flow velocity reduction characteristics
We conducted a parametric analysis of an Savonius hydrokinetic turbine (SHT) based on the number of blades, the blade shape, and the overlap ratio, considering the effect of flow velocity reduction
Summary
At this stage of rapid social and economic development, the energy crisis and environmental damage caused by traditional fossil resources are becoming increasingly prominent. As a renewable energy source, has the characteristics of large reserves, high energy density, and small environmental impact [1]. According to their structural characteristics, tidal energy capture devices can be divided into three categories: Vertical axis, horizontal axis, and oscillating hydrofoil. As a resistance-type vertical axis turbine, the Savonius hydrokinetic turbine (SHT) has a simple structure that is easy manufacture, good starting characteristics, and high dynamic moments [4]. It has no limit on flow direction and presents low noise and wear on moving parts
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