Quantification of the effects of geometric approximations on the performance of a vertical axis wind turbine

Siddiqui, M. Salman; Durrani, Naveed; Akhtar, Imran

doi:10.1016/j.renene.2014.08.068

Cited by 79 publications

(38 citation statements)

References 7 publications

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“…9 SMI has captured these variations adequately and produced reasonable results (see 10 ). Where as MRF failed to characterize these interactions, which are certainly there because of underlying steadiness in the solution.…”

Section: A Mrf Vs Smimentioning

confidence: 78%

Numerical Modeling Framework for Wind Turbine Analysis & Atmospheric Boundary Layer Interaction

Siddiqui

Rasheed

Tabib

et al. 2017

35th Wind Energy Symposium

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Prevailing atmospheric conditions can have a significant impact on the performance of large mega-watt wind turbines. A purely experimental evaluation of this impact is currently not possible and hence numerical techniques have been employed in this work. With the focus on aerodynamic performance of wind turbine, an attempt is made to realize the following objectives: (a) To evaluate the predictive capabilities of fully resolved Sliding Mesh Interface (SMI) transient simulations around the wind turbine against the steady state Multiple Reference Frame (MRF) simulations (b) To investigate the performance of the wind turbine subjected to uniform inlet profiles against atmospheric boundary layer profiles. (c) To study the effect of atmospheric stability on wind turbine performance. The methods are validated first and then implemented on a national renewable energy laboratory 5 MW reference wind turbine model for the aerodynamic study. Highly uneven and irregular wake profiles are seen with variation in input conditions(TKE). Uneven distribution of flow velocity in the lateral direction enhances the momentum transfer with in the shear layers and contributes positively towards the wake recovery. It is also found that in unstable stratified conditions, the positive buoyancy flux at the surface creates thermal instabilities which enhances the turbulent kinetic energy and the turbulent mixing, and helps the wake to recover faster.

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Section: A Mrf Vs Smimentioning

confidence: 78%

Numerical Modeling Framework for Wind Turbine Analysis & Atmospheric Boundary Layer Interaction

Siddiqui

Rasheed

Tabib

et al. 2017

35th Wind Energy Symposium

Self Cite

View full text Add to dashboard Cite

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“…Siddiqui et al [12] numerically quantified the effects of the geometric modeling on the performance of a vertical axis wind turbine. They evaluated several approximations: 2D computations, 2.5D approximation (i.e., extrusion of the 2D grid with symmetry boundary condition at the blades span), 3D geometry considering blades only and 3D simulation with blades, shaft and arms.…”

Section: Introductionmentioning

confidence: 99%

Numerical Study of the Effect of Winglets on the Performance of a Straight Blade Darrieus Water Turbine

2018

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This study deals with the three-dimensional unsteady numerical simulation of the flow around a cross-flow vertical-axis water turbine (CFWT) of the Darrieus type. The influence of turbine design on its hydrodynamic characteristics and performance is investigated by means of a time-accurate Reynolds Averaged Navier Stokes (RANS) commercial solver. The flow unsteadiness is described using a transient rotor-stator model in connection with a sliding interface. A classical Darrieus straight blade turbine, based on the NACA0025 airfoil, has been modified adding winglets (symmetric and asymmetric designs) to the blades' tips with the objective of reducing the strength of the detached trailing vortices. The turbulent features of the flow have been modelled by using different turbulence models (k-ε Renormalization Group, standard Shear Stress Transport, transition Shear Stress Transport and Reynolds Stress Model). As a result, the predicted hydrodynamic performance of the turbine including winglets increases, independently of the employed turbulence model, being the improvement higher when a symmetric winglet design is considered. Moreover, visualization of skin friction lines pattern and their connection with vorticity isosurfaces, illustrating the flow detachment in the three blade configurations, has been carried out. Finally, a short discussion about the intermittency behavior along a turbine revolution is presented.

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“…It is, therefore, vital to resolve the wake to study the complex physics inside wind farms, depending on the rotor size and the blade aerodynamic characteristics. To perform such task, there are various types of methods available depending on the level of complexity to evaluate the aerodynamic behavior of wind turbines [5]. One of the most widely used analytical technique is the use of the Blade Element Momentum (BEM) theory.…”

Section: Introduction and Objectivementioning

confidence: 99%

“…Recent advancement of computers nowadays, the Computational Fluid Dynamics (CFD) is becoming a vital alternative [9]. It also offers certain advantages concerning qualitative analysis, visualizations of pressure distribution on turbine blade surfaces and evaluation of the dynamic behavior under variable inflow conditions can be explicitly formulated [5]. It is not unique in the sense of computational cost.…”

Section: Introduction and Objectivementioning

confidence: 99%

Influence of Tip Speed Ratio on Wake Flow Characteristics Utilizing Fully Resolved CFD Methodology

Siddiqui

Rasheed

Kvamsdal

et al. 2017

J. Phys.: Conf. Ser.

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Abstract. Dominant flow structures in the wake region behind the turbine employed in the Blind Test campaign [1], [2] is investigated numerically. The effect on the wake configuration at variable operating conditions are studied. The importance of the introduction of turbine tower inside the numerical framework is highlighted. High-fidelity simulations are performed with Multiple Reference Frame (MRF) numerical methodology. A thorough comparison among the cases is presented, and the wake evolution is analyzed at variable stations downstream of the turbine. Streamlines of flow field traveled towards ground adjacent to turbine tower and strongly dependent on the operating tip speed ratio. Wake is composed of tower shadow superimposed by rotor wake. Shadow of the tower varies from x/R=2 until x/R=4 and breaks down into small vortices with the interaction of rotor wake. This study also shows that the wake distribution consists of two zones; inner zone composed of disturbances generated by blade root, nacelle and the tower, and an outer zone consisting of tip vortices.

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Quantification of the effects of geometric approximations on the performance of a vertical axis wind turbine

Cited by 79 publications

References 7 publications

Numerical Modeling Framework for Wind Turbine Analysis & Atmospheric Boundary Layer Interaction

Numerical Modeling Framework for Wind Turbine Analysis & Atmospheric Boundary Layer Interaction

Numerical Study of the Effect of Winglets on the Performance of a Straight Blade Darrieus Water Turbine

Influence of Tip Speed Ratio on Wake Flow Characteristics Utilizing Fully Resolved CFD Methodology

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