Computation of dynamic stall of a NACA-0012 airfoil

AIAA Journal ◽  
1987 ◽  
Vol 25 (3) ◽  
pp. 408-413 ◽  
Author(s):  
Yoshifumi Shida ◽  
Kunio Kuwahara ◽  
Kiyoaki Ono ◽  
Hideo Takami
Keyword(s):  
Dynamic Stall ◽  
Naca 0012

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

2018 ◽  
Vol 140 (6) ◽  
Author(s):  
Pablo Ouro ◽  
Thorsten Stoesser ◽  
Luis Ramírez
Keyword(s):  
Vertical Axis ◽  
Dynamic Stall ◽  
Hysteresis Cycle ◽  
Aerodynamic Coefficients ◽  
Pitching Motion ◽  
Large Eddy ◽  
Naca 0012 ◽  
Drag Ratio ◽  
Lift To Drag Ratio ◽  
Good Agreement

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.

scholarly journals Investigation of Flow Field in Deep Dynamic Stall over an Oscillating NACA 0012 Airfoil

2019 ◽  
Vol 12 (3) ◽  
pp. 857-863
Author(s):  
D. Surekha R. S. ◽  
A. Khandelwal ◽  
R. Rajasekar ◽  
◽  
◽  
...  
Keyword(s):  
Flow Field ◽  
Dynamic Stall ◽  
Naca 0012

Manuscript title: Effect of spanwise groove on the dynamic stall characteristics of an airfoil

2021 ◽  
pp. 095441002110652
Author(s):  
Rajesh Yadav ◽  
Aslesha Bodavula
Keyword(s):  
Turbine Blades ◽  
Dynamic Stall ◽  
Wind Turbine Blades ◽  
Helicopter Rotors ◽  
Sst Turbulence Model ◽  
Circular Frequency ◽  
The Mean ◽  
The Right ◽  
Naca 0012 ◽  
Viscous Stresses

Numerical simulations are conducted to investigate the effect of triangular groove on the dynamic stall characteristics of a NACA 0012 airfoil at a Reynolds number of 135,000. The right-angled triangular grooves are placed at either 10%, 25%, or 50% chord locations on the suction and have depths of 0.025c and 0.05c, measured normal to the surface of the airfoil. The solutions that are second order accurate in time and space are obtained using pressure-based finite volume solver and the 4-equation transition SST turbulence model viz. γ- Re θt is used to predict transition and viscous stresses accurately. The airfoil is in harmonic pitch motion about its quarter-chord with a maximum circular frequency of 18.67 rad/s. The results suggest that the presence of a groove, except for the deeper grove at 0.5c, quickens the dynamic stall, but with smaller rise in C l,max and a less severe fall in lift at the stall. The mean C l value during the downstroke is improved by up to 8% for the deeper groove at 0.25c, reducing the hysteresis in lift significantly. The grooves at 0.1c, 0.25c, and 0.5c also reduce the drag by 4%, 7%, and 9% during a complete cycle, with subsequent improvements of 54%, 69%, and 63% in the l/d ratio. The current finding can be thus used to enhance the performance of flapping wing MAVs, helicopter rotors, and wind turbine blades as these applications encounter the dynamic stall phenomena frequently.

Dynamic Stall Model with Circulation Pulse and Static Hysteresis for NACA 0012 and VR-12 Airfoils

2016 ◽  
Vol 61 (3) ◽  
pp. 1-10 ◽  
Author(s):  
Ramin Modarres ◽  
David A. Peters ◽  
Jacob Gaskill
Keyword(s):  
Dynamic Stall ◽  
Naca 0012

Water Tunnel Visualizations of Dynamic Stall

1979 ◽  
Vol 101 (3) ◽  
pp. 376-380 ◽  
Author(s):  
K. W. McAlister ◽  
L. W. Carr
Keyword(s):  
Steady Flow ◽  
Dynamic Stall ◽  
Water Tunnel ◽  
Bubble Flow ◽  
Hydrogen Bubble ◽  
Two Dimensional ◽  
Airfoil Surface ◽  
Flow Visualizations ◽  
Stall Angle ◽  
Naca 0012

A two-dimensional experiment was conducted in a water tunnel using hydrogen bubble flow visualizations for the purpose of exposing, independently, the behavior of the viscous and inviscid domains during unsteady airfoil stall. By imposing a large amplitude pitch oscillation about the static-stall angle of a modified NACA 0012 airfoil, an unsteady environment was created that not only altered considerably the progression of flow reversal along the airfoil surface from what was observed in steady flow, but also caused a unique succession of vortical developments to appear that is unparalleled in steady flow.

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