Author: Jennifer L. PricePublisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
Unsteady Aerodynamic Measurements Using Multi-element Hot-film Arrays on an Oscillating Airfoil with Gurney Flaps
Author: Jennifer L. PriceUnsteady Measurements and Computations on an Oscillating Airfoil with Gurney Flaps
Author: Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
The effect of a Gurney flap on an unsteady airfoil flow is experimentally and computationally examined. In the experiment, the details of the unsteady boundary layer events on the forward portion of the airfoil are measured. In the computation, the features of the global unsteady flow are documented and correlated with the experimental observations. The experiments were conducted in the North Carolina State University subsonic wind tunnel on an oscillating airfoil at pitch rates of 65.45 degrees/sec and 130.9 degrees/sec. The airfoil has a NACA0012 cross-section and is equipped with a 1.5% or 2.5% chord Gurney flap. The airfoil is tested at Reynolds numbers of 96,000, 169,000 and 192,000 for attached and light dynamic stall conditions. An array of surface-mounted hot-film sensors on the forward 25% chord of the airfoil is used to measure the unsteady laminar boundary layer separation, transition-to-turbulence, and turbulent reattachment. In parallel with the experiments incompressible Navier-Stokes computations are conducted for the light dynamic stall conditions on the airfoil with a 2.5%c Gurney flap at a Reynolds number of 169,000. The experimental measurements show that the effect of the Gurney flap is to move the separation, transition and reattachment forward on the airfoil. This effect is more marked during the airfoil's pitch-down than during pitch-up. The computational results verify these observations, and also show that the shedding of the dynamic stall vortex is delayed. Thus the adverse effects of dynamic stall are mitigated by the Gurney flap.
Unsteady Measurements and Computations on an Oscillating Airfoil with Gurney Flaps
Author: Jennifer Lou PricePublisher:
ISBN:
Category :
Languages : en
Pages : 62
Book Description
Keywords: hot-film sensors, INS2D, CVA, constant voltage anemometer.
Aerospace America
Author: An Experimental and Computational Investigation of Oscillating Airfoil Unsteady Aerodynamics at Large Mean Incidence
Author: Publisher: DIANE Publishing
ISBN: 1428995161
Category :
Languages : en
Pages : 42
Book Description
Studies in Unsteady Aerodynamics of Multi-element Airfoils
Author: James Chen-yuan WuPublisher:
ISBN:
Category : Aerodynamics
Languages : en
Pages : 32
Book Description
Transient Aerodynamic Behavior of an Airfoil Due to Different Arbitrary Modes of Nonstationary Motions in a Supersonic Flow
Author: Chieh-Chien ChangPublisher:
ISBN:
Category : Aerodynamics, Supersonic
Languages : en
Pages : 74
Book Description
An investigation is made of the transient behavior of an airfoil n supersonic flow due to pitching, flapping, and vertical gusts by means of a Fourier integral method.
Initial Unsteady Aerodynamic Measurements of a Circulation Controlled Airfoil and an Oscillating Flow Wind Tunnel
Author: Emmett John LancasterPublisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 73
Book Description
Steady state results of lift developed by varying the momentum blowing coefficient C sub mu upon a refurbished Circulation Control Rotor (CCR) airfoil section were favorable. This thesis was an experimental investigation to quantitatively evaluate whether the steady state results could be applied by a quasi-steady assumption when a harmonic perturbation of C sub mu was superimposed upon the steady value. Results suggested an attenuation in the dynamic transfer function of dC sub P/d C sub mu as the oscillating blowing frequency was increased. Initial measurements indicated that the RMS C sub P perturbation was an order of magnitude greater than the normalized RMS velocity perturbation. To further clarify this situation, investigations were conducted to establish a dynamic frequency response calibration of the wind tunnel. Results confirmed the order of magnitude difference between the RMS C sub P and normalized RMS velocity perturbations, indicating, that the tunnel flow environment was governed by Euler's equation in its complete form rather than with the simplifications which lead to the quasi-steady small perturbation theory.
Initial Unsteady Aerodynamic Measurements of a Circulation Controlled Airfoil and an Oscillating Flow Wind Tunnel
Author: Publisher:
ISBN:
Category :
Languages : en
Pages : 0
Book Description
Steady state results of lift developed by varying the momentum blowing coefficient C sub mu upon a refurbished Circulation Control Rotor (CCR) airfoil section were favorable. This thesis was an experimental investigation to quantitatively evaluate whether the steady state results could be applied by a quasi-steady assumption when a harmonic perturbation of C sub mu was superimposed upon the steady value. Results suggested an attenuation in the dynamic transfer function of dC sub P/d C sub mu as the oscillating blowing frequency was increased. Initial measurements indicated that the RMS C sub P perturbation was an order of magnitude greater than the normalized RMS velocity perturbation. To further clarify this situation, investigations were conducted to establish a dynamic frequency response calibration of the wind tunnel. Results confirmed the order of magnitude difference between the RMS C sub P and normalized RMS velocity perturbations, indicating, that the tunnel flow environment was governed by Euler's equation in its complete form rather than with the simplifications which lead to the quasi-steady small perturbation theory.
Unsteady Aerodynamics of a Flapping Airfoil
Author: Sunetra SarkarPublisher: LAP Lambert Academic Publishing
ISBN: 9783838347592
Category :
Languages : en
Pages : 204
Book Description
This book analyzes the unsteady, viscous flow-field of an oscillating airfoil. This has ramifications on understanding the flapping flight of natural biological systems like fishes and invertebrates. It also helps towards a better aerodynamic design and understanding of flapping types MAVs. The flow-field simulation is performed with a grid-free Lagrangian particle based solver using vorticity particles. An examination of the unsteady aerodynamic load and the qualitative wake structures are done for airfoils undergoing pitch and plunge oscillations. The propulsive behavior is investigated at medium to high frequency ranges for different relevant parameters. These are amplitude of oscillation, mean angle of attack, and rotational axis location. Asymmetric sinusoidal motions are also examined. Dynamic stall is another important aspect of unsteady aerodynamics that airfoils and wings experience during their time dependent movement at large angles of attack. Insects use this phenomenon to increase the aerodynamic loads during their large angle flapping maneuvers. This aspect is also studied in this book.