scholarly journals Turbulence-Model Comparison for Aerodynamic-Performance Prediction of a Typical Vertical-Axis Wind-Turbine Airfoil

Energies ◽  
2019 ◽  
Vol 12 (3) ◽  
pp. 488 ◽  
Author(s):  
Andrés Meana-Fernández ◽  
Jesús Fernández Oro ◽  
Katia Argüelles Díaz ◽  
Sandra Velarde-Suárez
Keyword(s):  
Flow Field ◽  
Turbulence Model ◽  
Model Comparison ◽  
Turbulence Models ◽  
Vertical Axis ◽  
Detached Eddy Simulation ◽  
Vertical Axis Wind Turbine ◽  
Aerodynamic Forces ◽  
Navier Stokes Equation ◽  
Rans Models

In this work, different turbulence models were applied to predict the performance of a DU-06-W-200 airfoil, a typical choice for vertical-axis wind turbines (VAWT). A compromise between simulation time and results was sought, focusing on the prediction of aerodynamic forces and the developed flow field. Reynolds-averaged Navier–Stokes equation (U-RANS) models and Scale-Resolving Simulations (SRS), such as Scale-Adaptive Simulation (SAS) and Detached Eddy Simulation (DES), were tested, with k − ω -based turbulence models providing the most accurate predictions of aerodynamic forces. A deeper study of three representative angles of attack (5 ° , 15 ° , and 25 ° ) showed that U-RANS models accurately predict aerodynamic forces with low computational costs. SRS modeling generates more realistic flow patterns: roll-up vortices, vortex packets, and stall cells have been identified, providing a richer unsteady flow-field description. The power spectrum density of velocity at 15 ° has confirmed a broadband spectrum in DES simulations, with a small peak at a Strouhal number of 0.486. Finally, indications regarding the selection of the turbulence model depending on the desired outcome (aerodynamic forces, airfoil flow field, or VAWT simulation) are provided, tending toward U-RANS models for the prediction of aerodynamic forces, and SRS models for flow-field study.

Investigation of aerodynamic forces and flow field of an H-type vertical axis wind turbine based on bionic airfoil

Energy ◽  
2021 ◽  
pp. 122999
Author(s):  
Yanfeng Zhang ◽  
Zhiping Guo ◽  
Xinyu Zhu ◽  
Yuan Li ◽  
Xiaowen Song ◽  
...  
Keyword(s):  
Flow Field ◽  
Wind Turbine ◽  
Vertical Axis ◽  
Vertical Axis Wind Turbine ◽  
Aerodynamic Forces ◽  
Bionic Airfoil

scholarly journals Effects of turbulence models and grid densities on computational accuracy of flows over a vertical axis wind turbine

2018 ◽  
Vol 7 (3) ◽  
pp. 213-222
Author(s):  
Jaruwan Chaiyanupong ◽  
Tawit Chitsomboon
Keyword(s):  
Shear Stress ◽  
Wind Turbine ◽  
Turbulence Model ◽  
Turbulence Models ◽  
Vertical Axis ◽  
Operating Conditions ◽  
Speed Ratio ◽  
Vertical Axis Wind Turbine ◽  
Computational Accuracy ◽  
Shear Stress Transport

Flows through a vertical axis wind turbine (VAWT) are very complex due to their inherent unsteadiness caused by large variations of the angle of attacks as the turbine is rotating and changing its azimuth angles simultaneously. In addition, a turbine must go through a wide range of operating conditions especially the change in blade speed ratio (BSR). Accurate prediction of flows over VAWT using Reynolds-Averaged Navier-Stokes (RANS) model needs a well-tested turbulence model as well as a careful grid control around the airfoil. This paper aimed to compare various turbulence models and seek the most accurate one. Furthermore, grid convergence was studied using the Roache method to determine the sufficient number of grid elements around the blade section. The three-dimensional grid was generated by extrution from the two-dimensional grid along with the appropriate y+ controlling. Comparisons were made among the three turbulence models that are widely used namely: the RNG model, the shear stress transport k-ω model (SST) and the Menter’s shear stress transport k-ω model (transition SST). Results obtained clearly showed that turbulence models significantly affected computational accuracy. The SST turbulence model showed best agreement with reported experimental data at BSR lower than 2.35, while the transition SST model showed better results when BSR is higher than 2.35. In addition, grid extruding technique with y+ control could reduce total grid requirement while maintaining acceptable prediction accuracy.Article History: Received April 15th 2018; Received in revised form June 16th 2018; Accepted September 17th 2018; Available onlineHow to Cite This Article: Chaiyanupong,J and Chitsomboon, T. (2018) Effects of Turbulence Models and Grid Densities on Computational Accuracy of Flows Over a Vertical Axis Wind Turbine. Int. Journal of Renewable Energy Development, 7(3), 213-222.http://dx.doi.org/10.14710/ijred.7.3.213-222

The influence of flow field and aerodynamic forces on a straight-bladed vertical axis wind turbine

Energy ◽  
2016 ◽  
Vol 111 ◽  
pp. 260-271 ◽  
Author(s):  
Qing'an Li ◽  
Takao Maeda ◽  
Yasunari Kamada ◽  
Junsuke Murata ◽  
Kazuma Furukawa ◽  
...  
Keyword(s):  
Flow Field ◽  
Wind Turbine ◽  
Vertical Axis ◽  
Vertical Axis Wind Turbine ◽  
Aerodynamic Forces

scholarly journals Assessment of stress-blended eddy simulation model for accurate performance prediction of vertical axis wind turbine

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Taurista Perdana Syawitri ◽  
Yufeng Yao ◽  
Jun Yao ◽  
Budi Chandra
Keyword(s):  
Wind Turbine ◽  
Turbulence Model ◽  
Stokes Equations ◽  
Turbulence Models ◽  
Vertical Axis ◽  
Power Coefficient ◽  
Speed Ratio ◽  
Vertical Axis Wind Turbine ◽  
Content Type ◽  
Eddy Simulation

Purpose The aim of this paper is to assess the ability of a stress-blended eddy simulation (SBES) turbulence model to predict the performance of a three-straight-bladed vertical axis wind turbine (VAWT). The grid sensitivity study is conducted to evaluate the simulation accuracy. Design/methodology/approach The unsteady Reynolds-averaged Navier–Stokes equations are solved using the computational fluid dynamics (CFD) technique. Two types of grid topology around the blades, namely, O-grid (OG) and C-grid (CG) types, are considered for grid sensitivity studies. Findings With regard to the power coefficient (Cp), simulation results have shown significant improvements of predictions using compared to other turbulence models such as the k-e model. The Cp distributions predicted by applying the CG mesh are in good agreement with the experimental data than that by the OG mesh. Research limitations/implications The current study provides some new insights of the use of SBES turbulence model in VAWT CFD simulations. Practical implications The SBES turbulence model can significantly improve the numerical accuracy on predicting the VAWT performance at a lower tip speed ratio (TSR), which other turbulence models cannot achieve. Furthermore, it has less computational demand for the finer grid resolution used in the RANS-Large Eddy Simulation (LES) “transition” zone compared to other hybrid RANS-LES models. Originality/value To authors’ knowledge, this is the first attempt to apply SBES turbulence model to predict VAWT performance resulting for accurate CFD results. The better prediction can increase the credibility of computational evaluation of a new or an improved configuration of VAWT.

scholarly journals Effect of Pitch Parameters on Aerodynamic Forces of a Straight-Bladed Vertical Axis Wind Turbine with Inclined Pitch Axes

2021 ◽  
Vol 11 (3) ◽  
pp. 1033
Author(s):  
Jia Guo ◽  
Timing Qu ◽  
Liping Lei
Keyword(s):  
Wind Turbine ◽  
Vertical Axis ◽  
Speed Ratio ◽  
Incline Angle ◽  
Asymmetric Distribution ◽  
Vertical Axis Wind Turbine ◽  
Power Performance ◽  
Aerodynamic Forces ◽  
Ansys Fluent ◽  
Pitch Regulation

Pitch regulation plays a significant role in improving power performance and achieving output control in wind turbines. The present study focuses on a novel, pitch-regulated vertical axis wind turbine (VAWT) with inclined pitch axes. The effect of two pitch parameters (the fold angle and the incline angle) on the instantaneous aerodynamic forces and overall performance of a straight-bladed VAWT under a tip-speed ratio of 4 is investigated using an actuator line model, achieved in ANSYS Fluent software and validated by previous experimental results. The results demonstrate that the fold angle has an apparent influence on the angles of attack and forces of the blades, as well as the power output of the wind turbine. It is helpful to further study the dynamic pitch regulation and adaptable passive pitch regulation of VAWTs. Incline angles away from 90° lead to the asymmetric distribution of aerodynamic forces along the blade span, which results in an expected reduction of loads on the main shaft and the tower of VAWTs.

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

Energies ◽  
2019 ◽  
Vol 12 (8) ◽  
pp. 1446 ◽  
Author(s):  
Elie Antar ◽  
Amne El Cheikh ◽  
Michel Elkhoury
Keyword(s):  
Wind Turbine ◽  
Average Power ◽  
Vertical Axis ◽  
Power Coefficient ◽  
Speed Ratio ◽  
Optimized Design ◽  
Detached Eddy Simulation ◽  
Vertical Axis Wind Turbine ◽  
Eddy Simulation ◽  
Delayed Detached Eddy Simulation

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.

Numerical Simulation of the Aerodynamic Performance of a H-Type Wind Turbine during Self-Starting

2014 ◽  
Vol 529 ◽  
pp. 296-302 ◽  
Author(s):  
Wei Zuo ◽  
Shun Kang
Keyword(s):  
Flow Field ◽  
Wind Turbine ◽  
Pitch Angle ◽  
Turbulence Modeling ◽  
Vertical Axis ◽  
Aerodynamic Performance ◽  
Time Dependent ◽  
Two Dimensional ◽  
Vertical Axis Wind Turbine ◽  
Sst Turbulence Model

The aerodynamic performance and the bypass flow field of a vertical axis wind turbine under self-starting are investigated using CFD simulations in this paper. The influence of pitch angle variations on the performance of the wind turbine during self-starting is presented. A two-dimensional model of the wind turbine with three blades is employed. A commercial software FlowVision is employed in this paper, which uses dynamic Cartesian grid. The SST turbulence model is used for turbulence modeling, which assumes the flow full turbulent. Based on the comparison between the computed time-dependent variations of the rotation speed with the experimental data, the time-dependent variations of the torque are presented. The characteristics of self-starting of the wind turbine are analyzed with the pitch angle of 0o、-2oand 2o. The influence of pitch angle variations on two-dimensional unsteady viscous flow field through velocity contours is discussed in detail.

scholarly journals Comparative Study on CFD Turbulence Models for the Flow Field in Air Cooled Radiator

Processes ◽  
2020 ◽  
Vol 8 (12) ◽  
pp. 1687
Author(s):  
Chao Yu ◽  
Xiangyao Xue ◽  
Kui Shi ◽  
Mingzhen Shao ◽  
Yang Liu
Keyword(s):  
Flow Field ◽  
Transient Flow ◽  
Three Dimensional ◽  
Turbulence Models ◽  
Compartment Model ◽  
Navier Stokes ◽  
Engine Compartment ◽  
Detached Eddy Simulation ◽  
Eddy Simulation ◽  
Relevant Calculation

This paper compares the performances of three Computational Fluid Dynamics (CFD) turbulence models, Reynolds Average Navier-Stokes (RANS), Detached Eddy Simulation (DES), and Large Eddy Simulation (LES), for simulating the flow field of a wheel loader engine compartment. The distributions of pressure fields, velocity fields, and vortex structures in a hybrid-grided engine compartment model are analyzed. The result reveals that the LES and DES can capture the detachment and breakage of the trailing edge more abundantly and meticulously than RANS. Additionally, by comparing the relevant calculation time, the feasibility of the DES model is proved to simulate the three-dimensional unsteady flow of engine compartment efficiently and accurately. This paper aims to provide a guiding idea for simulating the transient flow field in the engine compartment, which could serve as a theoretical basis for optimizing and improving the layout of the components of the engine compartment.

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