Investigation of Transition and Vortex Systems of a Dynamically Pitching Airfoil Under the Free-stream Turbulence Conditions PDF Download
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Author: Anurag Gandhi
Publisher:
ISBN:
Category : Aerofoils
Languages : en
Pages : 0
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Book Description
The effect of reduced frequency on dynamic stall behavior of a pitching NACA0012 airfoil in a turbulent wake using Direct Numerical Simulations is presented in the current study. Upstream turbulence with dynamically oscillating blades and airfoils is associated with ambient flow unsteadiness and is encountered in many operating conditions. Wake turbulence, a more realistic scenario for airfoils in operation, is generated using a small solid cylinder placed upstream, the vortices shed from which interact with the pitching airfoil affecting dynamic stall behavior. A recently developed moving overlapping grid approach is used using a high-order Spectral Element Method (SEM) for spatial discretization combined with a dynamic time-stepping procedure allowing for up to third order temporal discretization. Two cases of reduced frequency (k = 0:16 and 0:25) for airfoil oscillation are investigated and the change in dynamic stall behavior with change in reduced frequency is studied and documented using flow-fields and aerodynamic coefficients (Drag, Lift and Pitching Moment) with a focus on understanding vortex system dynamics (including formation of secondary vortices) for different reduced frequencies and it's affect on airfoil aerodynamic characteristics and fatigue life. Transition of the flow over the surface of an airfoil for both undisturbed and disturbed flow cases will also be discussed using Pressure coefficient and Skin Friction coefficient data for a given cycle combined with a wavelet analysis using Morse wavelets in MATLAB.
Author: Anurag Gandhi
Publisher:
ISBN:
Category : Aerofoils
Languages : en
Pages : 0
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Book Description
The effect of reduced frequency on dynamic stall behavior of a pitching NACA0012 airfoil in a turbulent wake using Direct Numerical Simulations is presented in the current study. Upstream turbulence with dynamically oscillating blades and airfoils is associated with ambient flow unsteadiness and is encountered in many operating conditions. Wake turbulence, a more realistic scenario for airfoils in operation, is generated using a small solid cylinder placed upstream, the vortices shed from which interact with the pitching airfoil affecting dynamic stall behavior. A recently developed moving overlapping grid approach is used using a high-order Spectral Element Method (SEM) for spatial discretization combined with a dynamic time-stepping procedure allowing for up to third order temporal discretization. Two cases of reduced frequency (k = 0:16 and 0:25) for airfoil oscillation are investigated and the change in dynamic stall behavior with change in reduced frequency is studied and documented using flow-fields and aerodynamic coefficients (Drag, Lift and Pitching Moment) with a focus on understanding vortex system dynamics (including formation of secondary vortices) for different reduced frequencies and it's affect on airfoil aerodynamic characteristics and fatigue life. Transition of the flow over the surface of an airfoil for both undisturbed and disturbed flow cases will also be discussed using Pressure coefficient and Skin Friction coefficient data for a given cycle combined with a wavelet analysis using Morse wavelets in MATLAB.
Author:
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 704
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Author:
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ISBN:
Category :
Languages : en
Pages : 0
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Book Description
The two-year project to study the dynamics of the leading-edge vortex (LEV) over a pitching airfoil under conditions of dynamic stall, was started in January 1990. Several accomplishments have been made during these two years. The most significant of these are (1) the construction of a special water channel suitable for the study of dynamic stall over a pitching airfoil, (2) the measurement of surface pressure distributions over the airfoil under several key operating conditions, and (3) development of the techniques of Particle Image Velocimetry (PIV) and its use in the measurement of instantaneous velocity and vorticity field in the two-dimensional flow around the airfoil. Some of these data which are the first of their kind have been used to understand the physics of unsteady vorticity dynamics over a pitching airfoil. These data are being made available to other investigators for use as database in validating their numerical models. Unsteady Aerodynamics, Dynamic Stall, Supermaneuverability, Vortex Dynamics.
Author:
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 980
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Author: Md. Ahsanul Karim
Publisher:
ISBN:
Category :
Languages : en
Pages : 322
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Author:
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ISBN:
Category : Aeronautics
Languages : en
Pages : 538
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Author: American Institute of Aeronautics and Astronautics
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 1252
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Author:
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ISBN:
Category : Mechanics, Applied
Languages : en
Pages : 630
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Author:
Publisher:
ISBN:
Category : Science
Languages : en
Pages : 1250
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Book Description
Author: Christopher E. Mertes
Publisher:
ISBN: 9781267424235
Category : Aerofoils
Languages : en
Pages : 87
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Book Description
An experimental study was conducted to characterize the effects of pitching motion on vortex shedding behavior in the wake of a flatback airfoil. Experiments were conducted on a static, rigidly mounted airfoil as well as an oscillating airfoil in a wind tunnel facility at the University of Wyoming. Particle image velocimetry was used in conjunction with proper orthogonal decomposition to show that the vortex shedding does behave differently depending on the dynamic configuration of the airfoil. The results show that fundamental vortex shedding from the blunt trailing edge is present in both the static and dynamic case whenever the flow is attached. In a case where the flow separates under dynamic stall conditions, the flow physics are dominated by the dynamic pitching motion, and trailing edge vortex shedding is only present during the attached portion of the pitching cycle. In another case, it was shown that the organization of the vortex shedding changes depending on the point in the oscillation cycle. This dynamic behavior has an impact on the aerodynamic characteristics of the blade.An experimental study was conducted to characterize the effects of pitching motion on vortex shedding behavior in the wake of a flatback airfoil. Experiments were conducted on a static, rigidly mounted airfoil as well as an oscillating airfoil in a wind tunnel facility at the University of Wyoming. Particle image velocimetry was used in conjunction with proper orthogonal decomposition to show that the vortex shedding does behave differently depending on the dynamic configuration of the airfoil. The results show that fundamental vortex shedding from the blunt trailing edge is present in both the static and dynamic case whenever the flow is attached. In a case where the flow separates under dynamic stall conditions, the flow physics are dominated by the dynamic pitching motion, and trailing edge vortex shedding is only present during the attached portion of the pitching cycle. In another case, it was shown that the organization of the vortex shedding changes depending on the point in the oscillation cycle. This dynamic behavior has an impact on the aerodynamic characteristics of the blade.
