A numerical investigation on the influence of savonius blade helicity on the performance characteristics of hybrid cross-flow hydrokinetic turbine

Md. Mustafa Kamal and R.P. Saini

Renewable Energy, 2022, vol. 190, issue C, 788-804

Abstract: One of the major drawbacks of having a hybrid cross-flow hydrokinetic turbine (HKT) is the alternative nature (positive and negative) of instantaneous torque generation by blades over one cycle of revolution, which will reduce the power coefficient and raise the pulsation level of instantaneous torque. Under the present study, the physical configuration of the proposed hybrid cross-flow HKT is altered by replacing the conventional Savonius HKT blade with a helical Savonius HKT blade. The numerical simulations have been carried out for five different hybrid HKT configurations with different Savonius blade helicity values as 0°, 45°, 90°, 135°, and 180° for the considered range of in-stream velocity from 0.5 m/s to 2.0 m/s. Based on the numerical study, the maximum power coefficient of hybrid cross-flow HKT having Savonius blade helicity of 45° was obtained as 0.208 corresponding to a TSR value of 0.9 and in-stream water velocity of 0.5 m/s. It is improved by 4.5%, in comparison to the maximum power coefficient obtained from the hybrid cross-flow HKT having conventional Savonius blade under the same flow conditions. The torque pulsation level for different configurations of hybrid HKT has also been analyzed in this study. The maximum reduction in TPF was observed as 31.54% for a hybrid cross-flow HKT model with a Savonius blade helicity of 180°. Further, it is observed that the negative magnitude of instantaneous torque generated by hybrid cross-flow HKT having Savonius blade helicity of 135° and 180°, completely nullified and positive instantaneous torque is achieved for all the values of rotor angle over one cycle of revolution. The transient nature of flow across turbine blades has also been visualized through velocity and pressure contours.

Keywords: Hybrid cross-flow HKT; CFD; TPF; Self-starting capability; Savonius blade helicity (search for similar items in EconPapers)
Date: 2022
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Citations: View citations in EconPapers (7)

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Persistent link: https://EconPapers.repec.org/RePEc:eee:renene:v:190:y:2022:i:c:p:788-804

DOI: 10.1016/j.renene.2022.03.155

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