Static and Dynamic Characteristics of Membrane Wings at Low Reynolds Number PDF Download
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Author: Zheng Zhang
Publisher:
ISBN:
Category : Electronic dissertations
Languages : en
Pages : 207
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Book Description
To lessen the deterioration of fixed-wing aerodynamic performance associated with Reynolds numbers (Re) below 100,000, flexible membrane wing designs have been studied and proposed as an alternative for micro air vehicle (MAV) use. The beneficial effects of a flexible membrane can include higher lift, steeper lift-curve slope, delayed stall, gentle stall characteristics, and greater efficiency. These benefits have been attributed to both the time-averaged and dynamic deformation of the membrane. The background literature search shows that few investigations regarding membrane wings have focused on low aspect ratio (AR) wings (AR
Author: Zheng Zhang
Publisher:
ISBN:
Category : Electronic dissertations
Languages : en
Pages : 207
Get Book Here
Book Description
To lessen the deterioration of fixed-wing aerodynamic performance associated with Reynolds numbers (Re) below 100,000, flexible membrane wing designs have been studied and proposed as an alternative for micro air vehicle (MAV) use. The beneficial effects of a flexible membrane can include higher lift, steeper lift-curve slope, delayed stall, gentle stall characteristics, and greater efficiency. These benefits have been attributed to both the time-averaged and dynamic deformation of the membrane. The background literature search shows that few investigations regarding membrane wings have focused on low aspect ratio (AR) wings (AR
Author: Amory W. Timpe
Publisher:
ISBN:
Category :
Languages : en
Pages : 112
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Book Description
Membrane oscillations are shown to manipulate the flow causing enhanced turbulent characteristics and favorable mean flow fields. Spectral and correlation analysis show quantitative evidence of membrane vibrations driving flow behavior both over the wing and in its wake.
Author: Andrew Harley Wrist
Publisher:
ISBN:
Category : Electronic dissertations
Languages : en
Pages : 98
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Book Description
The limited size of micro air vehicles (MAVs) requires small power sources, leading to a need for high aerodynamic efficiency. Flexible membrane wings at the MAV scale can experience improved lift/drag ratios, delays in stall, and decreased time-averaged flow separation when compared to rigid wings. This research thesis examines the effect of frame camber on the aerodynamic characteristics of membrane wings. The frames for the wings were designed in SolidWorks and constructed using an Objet30 Pro 3D printer. The membranes are composed of silicone rubber. Tests were conducted in The University of Alabama low-speed wind tunnel in 135 Hardaway Hall in low Reynolds number flow (Re ~ 50,000). Aerodynamic force and moment measurements were acquired at angles-of-attack varying from -4 to 24°. The results were used to determine whether cambered frames provide membrane wings with aerodynamic advantages when compared to those with flat frames. Additionally, a digital image correlation (DIC) camera system was used to acquire time-averaged shapes for the membrane wings during wind tunnel tests. The wings were mounted vertically at angles-of-attack of 6° and 18° to represent the regions of maximum efficiency and approaching stall, respectively. An in-house MATLAB program was developed to average the deflection plots from the images and produce time-averaged shapes. Lifting-line theory was applied to the time-averaged shapes to calculate theoretical lift and induced drag coefficients. The experimental set-up, results, and conclusions are discussed.
Author: Trenton James Carpenter
Publisher:
ISBN:
Category : Aerodynamic load
Languages : en
Pages : 118
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Book Description
Through passive adaptation to incidental flow, flexible aerodynamic surfaces exploit effects of increased lift, delayed stall and disturbance rejection. Wings of birds, bats, and insects exhibit these passive effects, and at the same time through the use of structural state feedback sensed from the loads on the wing, active control is applied to achieve stable and highly dynamic maneuvers. The goal of this research is to predict aerodynamic loads on flexible wings, by sensing their structural responses to static and dynamic airflow conditions. Three approaches are presented to estimate aerodynamic loads on highly flexible membrane wings, under static and dynamic conditions, at low Reynolds number. The first applies a linear membrane formulation to correlate the wing's structural strain to lift, through wing-tip vorticity. In the second, the Poisson equation for a 2D linear-elastic membrane with out-of-plane deformation was used to calculate normal pressure distribution from virtual strain sensors using proper orthogonal decomposition basis functions and a recursive least squares minimization. Finally, potential flow theory and a first order state space representation is applied to the transient flow effects around a pitching membrane airfoil to model the time varying loads due to dynamic pitching.
Author: Beng Poh Lee
Publisher:
ISBN:
Category : Reynolds number
Languages : en
Pages : 166
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Author:
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 1056
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Author:
Publisher:
ISBN:
Category : Mechanics, Applied
Languages : en
Pages : 252
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Author: Robert E. Shanks
Publisher:
ISBN:
Category : Aerodynamic measurements
Languages : en
Pages : 822
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Author:
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 456
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Author: Luke Tregidgo
Publisher:
ISBN:
Category :
Languages : en
Pages :
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