Investigations on the Effect of Radius Rotor in Combined Darrieus-Savonius Wind Turbine

Kaprawi Sahim,Dyos Santoso,Dewi Puspitasari

doi:10.1155/2018/3568542

Kaprawi Sahim, Dyos Santoso + Show 1 more

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https://doi.org/10.1155/2018/3568542

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Abstract

Renewable sources of energy, abundant in availability, are needed to be exploited with adaptable technology. For wind energy, the wind turbine is very well adapted to generate electricity. Among the different typologies, small scale Vertical Axis Wind Turbines (VAWT) present the greatest potential for off-grid power generation at low wind speeds. The combined Darrieus-Savonius wind turbine is intended to enhance the performance of the Darrieus rotor in low speed. In combined turbine, the Savonius buckets are always attached at the rotor shaft and the Darrieus blades are installed far from the shaft which have arm attaching to the shaft. A simple combined turbine offers two rotors on the same shaft. The combined turbine that consists of two Darrieus and Savonius blades was tested in wind tunnel test section with constant wind velocity and its performance was assessed in terms of power and torque coefficients. The study gives the effect of the radius ratio between Savonius and Darrieus rotor on the performance of the turbine. The results show that there is a significant influence on the turbine performance if the radius ratio was changed.

Highlights

Darrieus and Savonius wind turbines are the most common Vertical Axis Wind Turbines (VAWT)
It is the reason that the objective of the present study is to explore experimentally the performance of a combined Darrieus and Savonius wind turbine
The solo Savonius rotor has a higher coefficient for low speed compared to solo Darrieus rotor and the torque coefficient decreases rapidly with λ in the narrow range of λ < 0.6

Summary

Introduction

Darrieus and Savonius wind turbines are the most common VAWTs. The Savonius wind turbine is an aerodynamically drag based, self-starting turbine with low cut in speed, but its inefficiency curtails it to fewer applications, whereas Darrieus wind turbines are aerodynamically lifting based turbines having higher cut in speed with higher coefficients of performance. The Savonius wind turbine is an aerodynamically drag based, self-starting turbine with low cut in speed, but its inefficiency curtails it to fewer applications, whereas Darrieus wind turbines are aerodynamically lifting based turbines having higher cut in speed with higher coefficients of performance It can rotate faster than the wind velocity. All turbines with vertical shaft have low power coefficient and the smallest power coefficient is Savonius turbine having maximum power coefficient 0.15 on λ ≈ 0.8

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