Abstract:
Hydrokinetic turbines are emerging as a prominent solution for green and
sustainable power generation. The Savonius hydrokinetic turbine, with its
simple design, low-cost, ease of installation, low noise, and good start-up
characteristics, is a promising technology for small-scale energy production.
However, its performance suffers from certain limitations such as low
efficiency and low starting torque. In this work, functionality of a
conventional Savonius Hydrokinetic turbine (SHKT) was assessed using
Computational Fluid Dynamics (CFD). The incorporation of streamlined bluff
bodies upstream of the returning blade induced a flow diversion towards the
advancing blade, consequently amplifying the power output. Cylinder,
diamond, D-shaped (Half cylinder) and flat deflector plate were used as
deflectors to analyse their impact on the turbine's performance. The results
revealed that the diamond-shaped bluff body, in contrast to the conventional
design, exhibited the maximum gain in turbine’s power coefficient (Cp) of up
to 31% more at Rx= 0.75D and Ry=0.51D, at tip speed ratio (λ) equal to 1.2.
The inclusion of cylinder-shaped and D-shaped bluff bodies yielded
significant improvements in turbine’s operational performance at a consistent
tip speed ratio (λ), with the former exhibiting a noteworthy increase of 11.83%
and the latter demonstrating a substantial enhancement of 19.89% in turbine’s
coefficient of power (Cp). At λ=1, the diamond-shaped bluff body achieved
turbine’s peak power coefficient (Cp) of 0.298, signifying its optimal
performance. Furthermore, through the inclusion of a 45o angled flat plate
deflector positioned ahead of the driving blade and in combination with the
diamond-shaped bluff body, the overall power coefficient (Cp) of the turbine
experienced an additional enhancement of 29.58% at a tip speed ratio (λ)=1.2.
Additionally, the diamond-shaped bluff body, in combination with a flat plate
deflector, demonstrated maximum average power coefficient (Cp) of 0.491 at a
tip speed ratio (λ)=0.8. This outcome demonstrates a notable improvement in
the performance of the Savonius Hydrokinetic turbine when utilizing upstream
bluff bodies and deflector plates. Thus, the use of these augmentation can
significantly increase the efficiency of the Savonius Hydrokinetic turbine
systems
