A Computational Fluid Dynamics Study of an Integrating Savonius-Darrieus Vertical Axis Wind Turbine

Abstract

To combine the advantages of performance of both Savonius and Darrieus wind turbines, this paper aims to study computationally a novel design configuration of a Vertical Axis Wind Turbine (VAWT). The new design would help cover a broad range of performance parameters between both types of wind turbines as well as overcome drawbacks of the Savonius type at higher rotational speed. The proposed design is to integrate both of Savonius and straight blade Darrieus wind turbines in a single VAWT design configuration. In this design, the turbine rotor consists of a number of similar NACA0015 airfoil blades set in a particular arrangement. By regulating individual angles of rotor blades, the turbine would work as either Savonius or H-Darrieus VAWT. The turbine could also be set to work at different configurations between those for the Savonius and H-Darrieus ones. The computational results revealed that the performance of the proposed integrating wind turbine would be controlled and optimized to cover the operating range of both of Savonius and Darrieus wind turbines. Besides, the performance of Savonius VAWT would be modified when applying this design. When the proposed design is practically implemented, characteristics of both of Savonius and H-Darrieus based wind turbines would be found in a single design.

Aerodynamic Characterization of Darrieus Turbines during Self-Start at different Azimuthal Quadrants

“…An additional method is by creating a hybrid Darrieus-Savonius type rotor, which can take advantage of the drag driven leeward quadrant. Following the work by Mahrous [46], such a turbine has shown to mitigate the large 𝑇 dip in the leeward quadrant at certain configurations. These methods of controlling 𝛼 are good strategies to mitigating negative torque generation in the leeward quadrants.…”

Computational Fluid Dynamics Study of a Modified Savonius Rotor Blade by Universal Consideration of Blade Shape Factor Concept

“…In the present study, the flow regime was turbulent, and the problem under consideration was solved in two-dimensional. The Reynolds-Averaged Navier-Stokes (RANS) equations are written in transient conditions as follows [31,36]. where  denotes the fluid density, t is the time, is the component of fluid velocity in the direction j, P is the pressure, g is the gravitational acceleration, µ is the coefficient of viscosity and refers to spatial coordinate.…”

“…During the calculations and in conjunction with the double precision pressure-based algorithm, second order upwind spatial discretization in pressure, momentum and turbulence equations was employed along with a Least Squares Cell Based algorithm for gradients. The time step of transient calculations was set corresponding to a 1o of turbine rotor rotation at each turbine angular velocity  (i.e.,  =  /180 ) [31]. It was reported in reference [35] that this value of time step provides an independent time step solution.…”

“…It was concluded that both torque and power coefficients are modified by increasing the number of stages. Mahrous [31] carried out a computational study to improve the performance of Savonius rotor by integrating both Savonius and Darrieus rotors in a single wind turbine design. The suggested design would work either as Savonius or Darrieus turbine depending on individual angles of rotor blades.…”