Numerical Investigation of Inner Blade Effects on the Conventional Savonius Rotor with External Overlap

Abstract

The Savonius wind turbine is considered as one of the best vertical axis wind turbines for harvesting the kinetic energy from the wind in the urban areas, due to magnificent features such as high starting torque, low construction and maintenance costs, simple design, and self-starting ability especially at low wind speed. However, the conventional style of the Savonius rotor suffers from low efficiency. Consequently, modifying the configuration of the rotor may be an appropriate solution for providing electricity to the communities with no access to the power grid. Thus, this study aims to enhance the performance of the conventional Savonius rotor with an external overlap by adding an inner blade to the rotor configuration. Hence, a comparison study between five new arrangements against the conventional rotor in terms of power coefficient (Cp) and torque coefficient (Ct) is performed through a two-dimensional simulation by using ANSYS Fluent 19.2. The k-ε/Realizable turbulence model is employed in the simulation. Results conclude that inner blade with an angle of 120° increases the power coefficient by 41%, 39%, and 7% at tip speed ratio (TSR) = 0.7, 0.6, and 0.5, respectively.

The effect of endplate addition on the performance of the savonius wind turbine: A 3-D study

“…The coefficient of performance is the nondimensional ratio of the mechanical power of the rotor to the power carried by the wind passing through the rotor swept area. The C P is calculated as explained by Jang et al 33 C P ¼ P mech 0:5ρAV 3 (1)…”

“…2 The VAWT is classified into two types based on the force of operation; the Darrius rotor is propelled by lift force, whereas the Savonius rotor is propelled by drag and lift. 3 The first Savonius wind turbine, developed by Sirgud Savonius, had a simple configuration of two semi-circular blades as shown in Figure 1. The Savonius wind turbine (SWT) is known for its low coefficient of power (C P ), which researchers have attempted to improve through computational and experimental studies.…”

“…Roy 20 did an additional study and discovered an optimal OR of 0.154. Recently, Al-ghriybah et al 21 affirmed that the optimal OR is 0.15. To further boost the structural integrity and the turbine performance, consideration of the appropriate aspect ratio is required.…”

“…2 The VAWT is classified into two types based on the force of operation; the Darrius rotor is propelled by lift force, whereas the Savonius rotor is propelled by drag and lift. 3…”

Performance Analysis of a Modified Savonius Rotor Using a Variable Blade Thickness

“…Wind turbines family could be classified into two main sections based on the orientation of the shaft, i.e. the horizontal axis wind turbine (HAWT) where the rotational axis is in the same direction of the flow, and the vertical axis wind turbine (VAWT) in which the wind direction is perpendicular to the axis of rotation 8,9) . HAWT is the most efficient kind of wind turbine due to its great aerodynamics 10,11) .…”