CFD study of Savonius wind turbine: 3D model validation and parametric analysis

Ferrari, G.; Federici, Davide; Schito, Paolo; Inzoli, Fabio; Mereu, Riccardo

doi:10.1016/j.renene.2016.12.077

Cited by 142 publications

(48 citation statements)

References 17 publications

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“…There have been numerous attempts to capitalize on the aforementioned characteristics, and further improve the efficiencies of Savonius VAWTs using experimental and numerical techniques. Ferrari et al [12] carried numerical investigations and assessed the influence of rotor height on the performance of a Savonius VAWT. It was shown that the efficiency of the turbine improved with increased rotor height up to an asymptotic limit [12].…”

Section: Of 21mentioning

confidence: 99%

“…Ferrari et al [12] carried numerical investigations and assessed the influence of rotor height on the performance of a Savonius VAWT. It was shown that the efficiency of the turbine improved with increased rotor height up to an asymptotic limit [12]. Light was also shed on the importance of 3D computational fluid dynamics (CFDs), which yielded results in close agreement with experimental data.…”

Section: Of 21mentioning

confidence: 99%

“…Light was also shed on the importance of 3D computational fluid dynamics (CFDs), which yielded results in close agreement with experimental data. Despite its reduced computational cost, 2D CFDs resulted in overestimated power coefficient values, and a shift in the C p curve relative to experimental data [12]. Kamoji et al [13] tested a helical Savonius turbine with a 90 • twist angle using wind tunnel measurements.…”

Section: Of 21mentioning

confidence: 99%

See 2 more Smart Citations

A Dynamic Rotor Vertical-Axis Wind Turbine with a Blade Transitioning Capability

2019

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This work presents an optimized design of a dynamic rotor vertical-axis wind turbine (DR VAWT) which maximizes the operational tip-speed ratio (TSR) range and the average power coefficient (Cp) value while maintaining a low cut-in wind velocity. The DR VAWT is capable of mimicking a Savonius rotor during the start-up phase and transitioning into a Darrieus one with increasing rotor radius at higher TSRs. The design exploits the fact that with increasing rotor radius, the TSR value increases, where the peak power coefficient is attained. A 2.5D improved delayed detached eddy simulation (IDDES) approach was adopted in order to optimize the dynamic rotor design, where results showed that the generated blades’ trajectories can be readily replicated by simple mechanisms in reality. A thorough sensitivity analysis was conducted on the generated optimized blades’ trajectories, where results showed that they were insensitive to values of the Reynolds number. The performance of the DR VAWT turbine with its blades following different trajectories was contrasted with the optimized turbine, where the influence of the blade pitch angle was highlighted. Moreover, a cross comparison between the performance of the proposed design and that of the hybrid Savonius–Darrieus one found in the literature was carefully made. Finally, the effect of airfoil thickness on the performance of the optimized DR VAWT was thoroughly analyzed.

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Section: Of 21mentioning

confidence: 99%

Section: Of 21mentioning

confidence: 99%

Section: Of 21mentioning

confidence: 99%

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A Dynamic Rotor Vertical-Axis Wind Turbine with a Blade Transitioning Capability

2019

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“…The two-equations based k-ω SST (Shear Stress Transport) is used for the solution of the Reynolds stresses included in the RANS equations. The k-ω SST model has been widely employed in other relevant works, since the effects of blades are accurately captured [20][21][22]. Various schemes are used to discretize each term of the incompressible Navier Stokes equations, which are listed in Table 1.…”

Section: Numerical Modelmentioning

confidence: 99%

“…It is depicted in Figure 7 that both C P and C M numerical curves are in agreement with the experimental values, especially in the region where the turbine operates at the maximum power coefficients (between λ = 0.6 and λ = 1.2). The obtained results have also been compared against the numerical (digitized) values from the work performed by Ferrari et al [20], who investigated both two-dimensional and three-dimensional cases. Discrepancies are observed for higher TSR values (λ > 1.2) with both numerical C P and C M values being underestimated.…”

Section: Power and Torque Coefficient Curvesmentioning

confidence: 99%

Numerical Study of a Novel Concept for Manufacturing Savonius Turbines with Twisted Blades

2020

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This work presents a numerical study of the aerodynamic performance and the resulting flow field of two novel Savonius wind turbines with twisted blades. The novelty relies on the blade manufacturing process which is characterized by a ‘twisted cut’ through the central axis of a hollow cylinder (tube), followed by a partial twisted cut in the range of 90°. This approach does not require any expensive fabrication process such as blade molding and/or 3D prints, and, therefore, it can potentially mitigate the production costs. The main goal is to investigate the operational parameters and the overall performance of the presented devices, which are currently being operated in atmospheric conditions. For this purpose, three-dimensional simulations have been performed using the open-source CFD library OpenFOAM in order to solve the governing equations and for characterizing the main phenomena involved in the flow pattern. The Reynolds-averaged Navier–Stokes (RANS) approach together with the k − ω SST model were employed to reproduce the flow turbulence effects. This model is validated using wind tunnel measurements of the power ( C P ) and torque ( C M ) coefficients from a straight blade Savonius turbine. Unsteady simulations of the two turbine prototypes were investigated at different tip speed ratio TSR ( λ ) by varying the rotational speed of the rotor while keeping constant the free stream (rated) velocity V ∞ . The results were compared against the Savonius turbine employed for validating the model. Aerodynamic loads and general wake structure were studied at the optimal operational conditions as well. For the same turbine configurations, the new blade geometry improved the performance by 20–25% (at its optimal TSR), compared to the conventional straight blade Savonius rotor, as well as the reducing torque fluctuation.

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Numerical modeling of flow past a volumeless and thin rigid body using direct forcing immersed boundary method

Tewolde

Wei

Chern

2022

Numerical Methods in Fluids

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The new capability has been added as the numerical method for modeling volumeless and thin rigid bodies to the direct forcing immersed boundary (DFIB) method. The DFIB approach is based on adding a virtual force to the Navier–Stokes equations of incompressible flow to account for the interaction between the fluid and structures. The volume of a solid function (VOS) identifies the stationary or moving solid structures in a given fluid domain. A new VOS‐based algorithm was developed to identify thin, rigid structure boundary points in fluid flow and ensure that the fluid cannot cross through the boundary of a thin rigid structure while moving or stationary. The DFIB method was first validated in a three‐dimensional (3D) turbulent flow over a circular cylinder. The large‐eddy simulation simulated the turbulent flow scales. The proposed algorithm was tested using a 3D turbulent flow past a stationary and rotating Savonius wind turbine that functions as a thin, rigid body. The validation results showed that the selected DFIB approach, combined with the novel algorithm, could simulate a thin, volumeless, rigid structure that is stationary and rotating in incompressible turbulent flows. The current method is also applicable for two‐way fluid‐structure interaction problems.

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CFD study of Savonius wind turbine: 3D model validation and parametric analysis

Cited by 142 publications

References 17 publications

A Dynamic Rotor Vertical-Axis Wind Turbine with a Blade Transitioning Capability

A Dynamic Rotor Vertical-Axis Wind Turbine with a Blade Transitioning Capability

Numerical Study of a Novel Concept for Manufacturing Savonius Turbines with Twisted Blades

Numerical modeling of flow past a volumeless and thin rigid body using direct forcing immersed boundary method

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