Modelling the effect of freestream turbulence on dynamic stall of wind turbine blades

Kim, Yusik; Xie, Zheng-Tong

doi:10.1016/j.compfluid.2016.02.004

Cited by 82 publications

(82 citation statements)

References 29 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Eddy-resolving approaches, such as large eddy simulation (LES), are able to compute the instantaneous flow field, which is required to accurately represent the time dependence of turbulence structures [14], such as the LEV present in the flow around pitching airfoils. Kim and Xie [15] obtained a good match with the experimental data from Lee and Gerontakos [7] using LES for various pitching frequencies. Their results evidenced that a remarkable improvement in the prediction of the LEV or laminar-to-turbulent shear layer transition is obtained when using LES instead of RANS.…”

Section: Introductionsupporting

confidence: 57%

“…Table 1 provides details for these two cases concerning: airfoil shape, Reynolds number (Re c ), pitching motion parameters, maximum (a max ) and minimum (a min ) pitch angle, and reference of the experiments used for the validations. The experimental work undertaken by Lee and Gerontakos [7] is selected for the baseline simulation, as it was reproduced using RANS [13,45,46], DES [13], and more recently with LES [15].…”

Section: Numerical Framework and Computational Setupmentioning

confidence: 99%

“…The simulations are run over four pitching cycles with the first cycle discarded from phase averaging of aerodynamic coefficients (similar to Ref. [15]), although during the experiments [7], averaging was performed for more than 100 cycles.…”

Section: Numerical Framework and Computational Setupmentioning

confidence: 99%

See 2 more Smart Citations

Effect of Blade Cambering on Dynamic Stall in View of Designing Vertical Axis Turbines

Ouro

Stoesser

Ramírez

2018

Journal of Fluids Engineering

View full text Add to dashboard Cite

This paper presents large eddy simulations (LESs) of symmetric and asymmetric (cambered) airfoils forced to undergo deep dynamic stall due to a prescribed pitching motion. Experimental data in terms of lift, drag, and moment coefficients are available for the symmetric NACA 0012 airfoil and these are used to validate the LESs. Good agreement between computed and experimentally observed coefficients is found confirming the accuracy of the method. The influence of foil asymmetry on the aerodynamic coefficients is analyzed by subjecting a NACA 4412 airfoil to the same flow and pitching motion conditions. Flow visualizations and analysis of aerodynamic forces allow an understanding and quantification of dynamic stall on both straight and cambered foils. The results confirm that cambered airfoils provide an increased lift-to-drag ratio and a decreased force hysteresis cycle in comparison to their symmetric counterparts. This may translate into increased performance and lower fatigue loads when using cambered airfoils in the design of vertical axis turbines (VATs) operating at low tip-speed ratios.

show abstract

Section: Introductionsupporting

confidence: 57%

Section: Numerical Framework and Computational Setupmentioning

confidence: 99%

See 1 more Smart Citation

Effect of Blade Cambering on Dynamic Stall in View of Designing Vertical Axis Turbines

Ouro

Stoesser

Ramírez

2018

Journal of Fluids Engineering

View full text Add to dashboard Cite

show abstract

“…It was shown that the reduced frequency was the most influential parameter on dynamic stall. Gharali et al [17] investigated the effects of the oscillations of the free-stream velocity on pitch oscillation by the SST k − ω model; Kim et al [18] studied the effects of free-stream turbulence on the aerodynamic characteristics of pitching airfoils by large eddy simulations. Gandhi et al [19] investigated the influence of reduced frequency on the dynamic stall characteristics of a NACA 0012 airfoil pitching in a turbulent wake with direct numerical simulations.…”

Section: Introductionmentioning

confidence: 99%

Aerodynamic Performance of Wind Turbine Airfoil DU 91-W2-250 under Dynamic Stall

Zhang

Yang

et al. 2018

Applied Sciences

View full text Add to dashboard Cite

Airfoils are subjected to the 'dynamic stall' phenomenon in significant pitch oscillations during the actual operation process of wind turbines. Dynamic stall will result in aerodynamic fatigue loads and further cause a discrepancy in the aerodynamic performance between design and operation. In this paper, a typical wind turbine airfoil, DU 91-W2-250, is examined numerically using the transition shear stress transport (SST) model under a Reynolds number of 3 × 10 5. The influence of a reduced frequency on the unsteady dynamic performance of the airfoil model is examined by analyzing aerodynamic coefficients, pressure contours and separation point positions. It is concluded that an increasingly-reduced frequency leads to lower aerodynamic efficiency during the upstroke process of pitching motions. The results show the movement of the separation point and the variation of flow structures in a hysteresis loop. Additionally, the spectrum of pressure signals on the suction surface is analyzed, exploring the level of dependence of pressure fluctuation on the shedding vortex and oscillation process. It provides a theoretical basis for the understanding of the dynamic stall of the wind turbine airfoil.

show abstract

“…Due to its accuracy, efficiency and in particular the capability for high Reynolds number follows, the synthetic inflow turbulence generator (Xie and Castro, 2008) has been implemented and tested on engineering type of codes, such as Star-CD (Xie and Castro, 2009) and OpenFOAM (Kim and Xie, 2016) and the micro-scale meteorology code PALM (PALM, 2017). This study will focus on an implementation of this synthetic inflow turbulence generator (Xie and Castro, 2008) in the idealised WRF-LES (v3.6.1) model under neutral atmospheric conditions.…”

mentioning

confidence: 99%

Implementation of a synthetic inflow turbulence generator in idealised WRF v3.6.1 large eddy simulations under neutral atmospheric conditions

Zhong¹,

Cai²,

Xie³

2019

Preprint

Self Cite

View full text Add to dashboard Cite

Abstract. A synthetic inflow turbulence generator was implemented in the idealised Weather Research and Forecasting large eddy simulation (WRF-LES v3.6.1) model under neutral atmospheric conditions. This method is based on an exponential correlation function, and generates a series of two-dimensional slices of data which are correlated both in space and in time. These data satisfy a spectrum with a near −5/3 inertial subrange, suggesting its excellent capability for high Reynolds number atmospheric flows. It is more computationally efficient than other synthetic turbulence generation approaches, such as three-dimensional digital filter methods. A WRF-LES model with periodic boundary conditions was configured to provide a priori turbulent information for the synthetic turbulence generation method and used as an evaluation for the inflow case. The comparison shows that the inflow case generated similar turbulence structures as these in the periodic case after a short adjustment distance. The inflow case yielded a mean velocity profile in a good agreement with the desired one, and 2nd order moment statistics profiles close to the desired ones after a short distance. For the range of the integral length scale which we tested, its influence on the profiles of the mean velocities is not significant, whereas its influence on the second moment statistics profiles is evident, in particular for very small integral length scales. This implementation can be extended to the WRF-LES simulation of a horizontally inhomogeneous case with non-repeated surface landuse pattern and a multi-scale seamless nesting case from a meso-scale domain with a km-resolution down to LES domains with metre resolutions.

show abstract

Modelling the effect of freestream turbulence on dynamic stall of wind turbine blades

Abstract: density of the streamwise velocity sampled from one point in the wake shows that the inertial sub-range tends to extend towards the pitching mode for the turbulent inflow, while there is a distinctive spectral gap for the laminar inflow.

Cited by 82 publications

References 29 publications

Effect of Blade Cambering on Dynamic Stall in View of Designing Vertical Axis Turbines

Effect of Blade Cambering on Dynamic Stall in View of Designing Vertical Axis Turbines

Aerodynamic Performance of Wind Turbine Airfoil DU 91-W2-250 under Dynamic Stall

Implementation of a synthetic inflow turbulence generator in idealised WRF v3.6.1 large eddy simulations under neutral atmospheric conditions

Contact Info

Product

Resources

About