Numerical study of dynamic stall on several airfoil sections

AIAA Journal ◽  
1999 ◽  
Vol 37 ◽  
pp. 128-130
Author(s):  
Emmanuel Guilmineau ◽  
Patrick Queutey
Keyword(s):  
Numerical Study ◽  
Dynamic Stall

scholarly journals Numerical Study on Dynamic-Stall Characteristics of Finite Wing and Rotor

2019 ◽  
Vol 9 (3) ◽  
pp. 600 ◽  
Author(s):  
Qing Wang ◽  
Qijun Zhao
Keyword(s):  
Numerical Study ◽  
Three Dimensional ◽  
Tip Vortex ◽  
Dynamic Stall ◽  
Navier Stokes ◽  
Governing Equations ◽  
Third Order ◽  
Finite Wing ◽  
Wing Tip ◽  
Spanwise Flow

To study the three-dimensional effects on the dynamic-stall characteristics of a rotor blade, the unsteady flowfields of the finite wing and rotor were simulated under dynamic-stall conditions, respectively. Unsteady Reynolds-averaged Navier–Stokes (URANS) equations coupled with a third-order Roe–MUSCL spatial discretization scheme were chosen as the governing equations to predict the three-dimensional flowfields. It is indicated from the simulated results of a finite wing that dynamic stall would be restricted near the wing tip due to the influence of the wing-tip vortex. By comparing the simulated results of the finite wing with the spanwise flow, it is indicated that the spanwise flow would arouse vortex accumulation. Consequently, the dynamic stall is restricted near the wing root and aggravated near the wing tip. By comparing the simulated results of a rotor in forward flight, it is indicated that the dynamic stall of the rotor would be inhibited due to the effects of the spanwise flow and Coriolis force. This work fills the gap regarding the insufficient three-dimensional dynamic stall of a helicopter rotor, and could be used to guide rotor airfoil shape design in the future.

Comparative Numerical Study of Two Turbulence Models for Airfoil Static and Dynamic Stall

AIAA Journal ◽  
1993 ◽  
Vol 31 (4) ◽  
pp. 784-786 ◽  
Author(s):  
Donald P. Rizzetta ◽  
Miguel R. Visbal
Keyword(s):  
Numerical Study ◽  
Turbulence Models ◽  
Dynamic Stall

scholarly journals Numerical Study of a Horizontal Wind Turbine under Yaw Conditions

2021 ◽  
Vol 2021 ◽  
pp. 1-17
Author(s):  
Alireza Arabgolarcheh ◽  
Sahar Jannesarahmadi ◽  
Ernesto Benini ◽  
Luca Menegozzo
Keyword(s):  
Wind Turbine ◽  
Wind Farm ◽  
Numerical Study ◽  
Wind Farms ◽  
Dynamic Stall ◽  
Horizontal Wind ◽  
Reference Case ◽  
Lower Velocity ◽  
Pressure Equalization ◽  
Model Code

Over recent years, considerable attention has been devoted to the optimization of energy production in wind farms, where yaw angles can play a significant role. In order to quantify and maximize such potential power, the simulation of wakes is vital. In the present study, an actuator line model code was implemented in the OpenFOAM flow solver. A tip treatment was applied to involve the tip effect induced by the pressure equalization from the suction and pressure sides. The Leishman–Beddoes dynamic stall (LB-DS) model modified by Sheng et al. was employed to consider the dynamic stall phenomenon. The developed ALM-CFD solver was validated for the NREL Phase VI wind turbine reference case. The solver was then used in simulating the yawed wind turbine, and power variation was compared with UBEM and CFD. Overall, according to the obtained data, the coupled solver compared well with CFD. There was an improvement in terms of prediction of the phase delay that is due to the dynamic stall. However, there was still negligible overestimation in deep stall conditions. Based on the obtained results, it is suggested that the reduction of power output follows a cosine to the power of X function of the yaw angle. In terms of visualizing wake, the results demonstrated that the current ALM code was satisfying enough to simulate skewed wake and vortices trajectory. The effect of advancing and retreating blade was captured. It was found that yaw led to the concentration of the induced velocity downstream, resulting in a lower velocity deficit on a broader area, which is essential for wind farm optimization.

Numerical study on a single bladed vertical axis wind turbine under dynamic stall

2017 ◽  
Vol 31 (1) ◽  
pp. 261-267 ◽  
Author(s):  
Galih Bangga ◽  
Go Hutomo ◽  
Raditya Wiranegara ◽  
Herman Sasongko
Keyword(s):  
Wind Turbine ◽  
Numerical Study ◽  
Vertical Axis ◽  
Dynamic Stall ◽  
Vertical Axis Wind Turbine

Dynamic Stall Alleviation Using a Deformable Leading Edge Concept-A Numerical Study

2003 ◽  
Vol 40 (1) ◽  
pp. 77-85 ◽  
Author(s):  
Mehmet Sahin ◽  
Lakshmi N. Sankar ◽  
M. S. Chandrasekhara ◽  
Chee Tung
Keyword(s):  
Numerical Study ◽  
Leading Edge ◽  
Dynamic Stall

A Numerical Study on the Performance Improvement for a Vertical-Axis Wind Turbine at Low Tip-Speed-Ratios

2017 ◽  
Author(s):  
Zhenyu Wang ◽  
Mei Zhuang
Keyword(s):  
Wind Speed ◽  
Wind Energy ◽  
Wind Turbines ◽  
Flow Separation ◽  
Power Output ◽  
Numerical Study ◽  
Leading Edge ◽  
Vertical Axis ◽  
Dynamic Stall ◽  
Energy Extraction

Vertical-axis wind turbines (VAWTs) are a promising solution for the use of renewable energy in residential areas. Compared to traditional horizontal-axis wind turbines (HAWTs), VAWTs are usually smaller, quieter, and insensitive to the wind direction and can be installed in a wide range of urban, suburban and rural places such as top of buildings, backyard, etc. In addition, VAWTs require a lower wind speed to self-start which increases the capability of wind energy extraction in the areas with low wind speed. However, VAWTs are less efficient and the power output of VAWTs is substantially affected by the phenomenon of dynamic stall induced by the variations of angle of attack of rotating blades, especially at low tip speed ratios (λTSR<4). When the dynamic stall vortices, formed near the leading-edge, are transported downstream, it creates large and sudden fluctuations in torques. At low values of the tip speed ratio and relatively low Reynolds number (Re<105), dynamic stall occurs periodically throughout the rotation of the blades. This results a sharp drop in lift coefficient and therefore rotor torque and power output are substantially reduced. The purpose of the present study is to investigate the prospects for improving the flow performances of small VAWTs using serrated leading-edge configurations on straight blades in a conventional H-type VAWT design to control dynamic flow separation. A numerical study is carried out to obtain the detailed flow fields for analysis and visualization. The results show that the turbine blade with the serration profiles of h = 0.025c (amplitude) and λs = 0.33c (wavelength) not only increased the power generation at low TSRs, but also enhanced the capability of wind energy extraction at the optimum TSR in comparison to the baseline model. The dynamic stall was suppressed significantly in the range of the azimuth angle from 80° to 160°. The flow separation induced by large angles of attack was essentially alleviated in the modified turbine model due to the serrated configuration implemented on the blade leading-edge.

scholarly journals Numerical Study of the Dynamic Stall Effect on a Pair of Cross-Flow Hydrokinetic Turbines and Associated Torque Enhancement due to Flow Blockage

2021 ◽  
Vol 9 (8) ◽  
pp. 829
Author(s):  
Minh N. Doan ◽  
Shinnosuke Obi
Keyword(s):  
Power Output ◽  
Numerical Study ◽  
Cross Flow ◽  
Leading Edge ◽  
Suction Side ◽  
Dynamic Stall ◽  
Navier Stokes ◽  
Hydrokinetic Turbines ◽  
Hydrokinetic Turbine ◽  
Direction Of Movement

An open-source 2D Reynolds-averaged Navier–Stokes (RANS) simulation model was presented and applied for a laboratory-scaled cross-flow hydrokinetic turbine and a twin turbine system in counter-rotating configurations. The computational fluid dynamics (CFD) model was compared with previously published experimental results and then used to study the turbine power output and relevant flow fields at four blockage ratios. The dynamic stall effect and related leading edge vortex (LEV) structures were observed, discussed, and correlated with the power output. The results provided insights into the blockage effect from a different perspective: The physics behind the production and maintenance of lift on the turbine blade at different blockage ratios. The model was then applied to counter-rotating configurations of the turbines and similar analyses of the torque production and maintenance were conducted. Depending on the direction of movement of the other turbine, the blade of interest could either produce higher torque or create more energy loss. For both of the scenarios where a blade interacted with the channel wall or another blade, the key behind torque enhancement was forcing the flow through its suction side and manipulating the LEV.

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