Experimental Study of Free Stream Turbulent Effects on Dynamic Stall of Pitching Airfoil by Using Particle Image Velocimetry

Leu, Tzong-Shyng; Yu, J.M.; Hu, Cheng Chao; Miau, Jiun‐Jih; Shi, Liang; Li, J. Y.; Cheng, Jen Chieh; Chen, S. J.

doi:10.4028/www.scientific.net/amm.225.103

Cited by 21 publications

(8 citation statements)

References 7 publications

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“…Over prediction of EFD Cp at high λ may also occur as a result of blockage effects that were not accounted for in the EFD results, which can artificially increase Cp by more than 25% as shown in previous EFD studies [20]. Prediction errors may also occur due to differences in the turbulence intensity levels between the CFD models and EFD testing, as high turbulence intensity levels can delay stall [21]. This can lead to increases in Cp especially at high λ [22].…”

Section: Computational Fluid Dynamics Simulationsmentioning

confidence: 96%

The influence of turbulence model and two and three-dimensional domain selection on the simulated performance characteristics of vertical axis tidal turbines

et al. 2017

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ABSTRACT:The influence of Computational Fluid Dynamics (CFD) modeling techniques on the accuracy of vertical axis turbine power output predictions was investigated. Using Two-Dimensional (2D) and Three-Dimensional (3D) models, as well as the Baseline-Reynolds Stress Models (BSL-RSM) model and the k-ω Shear Stress Transport (k-ω SST) model in its fully turbulent and laminar-to-turbulent formulation, differences in power output modeling accuracy were evaluated against experimental results from literature. The highest correlation with experimental power output was found using a 3D domain model that fully resolved the boundary layer combined with the k-ω SST laminar-to-turbulent model. The turbulent 3D fully resolved boundary layer k-ω SST model also accurately predicted power output for most rotational rates, at a significantly reduced computational cost when compared to its laminar-to-turbulent formulation. The 3D fully resolved BSL-RSM model and 3D wall function boundary layer k-ω SST model were found to poorly simulate power output. Poor output predictions were also obtained using 2D domain k-ω SST models, as they were unable to account for blade tip and strut effects. The authors suggest that 3D domain fully turbulent k-ω SST models with fully resolved boundary layer modeling are used for predicting turbine power output given their accuracy and computational efficiency.  2D CFD models cannot capture blade tip and strut effects resulting in poor power output simulation accuracy  3D CFD models can now accurately capture turbine power output without excessive computation requirements  The k-ω SST turbulence models provide the closest agreement with experimental results  Transition flow modeling is computationally demanding and only increases simulation accuracy at high rotational rates when compared to fully turbulent models  BSL-RSM and k-ω SST Wall Function models poorly simulate power output

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Section: Computational Fluid Dynamics Simulationsmentioning

confidence: 96%

The influence of turbulence model and two and three-dimensional domain selection on the simulated performance characteristics of vertical axis tidal turbines

et al. 2017

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“…Improvements of simulation accuracy at high λ may be possible using newly developed transitional turbulent models that can account for this laminar-turbulent transition behaviour [19]. Over prediction of Cp at high λ may also occur as a result of blockage errors that were not accounted for in EFD results which could artificially increase EFD Cp [26], and may also occur due to differences in the turbulence intensity levels between the CFD models and EFD testing, as high turbulence intensity levels can delay stall [27], leading to increases in Cp especially at high λ [28], with no turbulence intensity measurements recorded during EFD testing to compare to CFD turbulence levels. Significantly both CFD models were able to accurately capture the effect of geometrical changes on maximum Cp, which was simulated to within 14.3% and 6.3% of EFD results for turbines A and B…”

Section: Validation Of Numerical Simulations With Experimental Fluid mentioning

confidence: 99%

Three-dimensional numerical simulations of straight-bladed vertical axis tidal turbines investigating power output, torque ripple and mounting forces

et al. 2015

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Three straight-bladed vertical axis turbine designs were simulated using ThreeDimensional (3D) transient Computational Fluid Dynamics (CFD) models, using a commercial Unsteady Reynolds Averaged Navier-Stokes (URANS). The turbine designs differed in support strut section, blade-strut joint design and strut location to evaluate their effect on power output, torque fluctuation levels and mounting forces. Simulations of power output were performed and validated against Experimental Fluid Dynamics (EFD), with results capturing the impacts of geometrical changes on turbine power output. Strut section and blade-strut joint design were determined to significantly influence total power output between the three turbine designs, with strut location having a smaller but still significant effect. Maximum torque fluctuations were found to occur around the rotation speed corresponding to maximum power output and fluctuation levels increased with overall turbine efficiency. Turbine mounting forces were also simulated and successfully validated against EFD results. Mounting forces aligned with the inflow increased with rotational rates, but plateaued due to reductions in shaft drag caused by rotation and blockage effects. Mounting forces perpendicular to the inflow were found to be 75% less than forces aligned with the inflow. High loading force fluctuations were found, with maximum values 40% greater than average forces.

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“…For S-VAWTs, after the wind bypasses blades, the incoming flow becomes more complicated. According to previous studies [9,10,11,12], the performance of the downstream turbine is deteriorated by the wake, and therefore the distance between two S-VAWTs should be large enough to reduce the wake effect. The distance for VAWT is usually 15 times larger than the rotor diameter [1].…”

Section: Introductionmentioning

confidence: 99%

A novel wake energy reuse method to optimize the layout for Savonius-type vertical axis wind turbines

Zhang

Song

Mao

et al. 2017

Energy

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The long wake of a wind turbine has a significant impact on the performance of downstream turbines. Under the inspiration of migrating geese flying in a V or I formation to save energy, a novel wake energy reuse method is proposed to optimize the layout for Savonius-type vertical axis wind turbines (S-VAWT). VAWT wakes include a series of high speed and energy zones. On both sides of the upstream turbine, 16 7  transient two-dimensional numerical simulations are performed with Fluent to investigate wake structure, interaction effect and power coefficients (C p) of downstream turbines. Based on Kriging Method, a response surface model (Surrogate model) is created to describe the relationship between the optimization objective C p and layout positions. Finally, particle swarm optimization algorithm is applied to find the optimal relative layout position (5.25m,-2.18m) of the downstream turbine. The optimal position is located in the periodic high speed zone of the wake on the advancing blade side. And the optimal position is suitable for multi-turbines in a large wind farm. The optimization results show that C p of downstream turbines at optimal layout position is significantly increased from 0.2477 to 0.3044 (22.89% higher).

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Experimental Study of Free Stream Turbulent Effects on Dynamic Stall of Pitching Airfoil by Using Particle Image Velocimetry

Cited by 21 publications

References 7 publications

The influence of turbulence model and two and three-dimensional domain selection on the simulated performance characteristics of vertical axis tidal turbines

The influence of turbulence model and two and three-dimensional domain selection on the simulated performance characteristics of vertical axis tidal turbines

Three-dimensional numerical simulations of straight-bladed vertical axis tidal turbines investigating power output, torque ripple and mounting forces

A novel wake energy reuse method to optimize the layout for Savonius-type vertical axis wind turbines

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