Control of Vortex Breakdown on a Delta Wing by Leading Edge Blowing and Suction PDF Download
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Author: H. Q. Yang
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Author: H. Q. Yang
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Author: Yair Guy
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Author: Ismet Gursul
Publisher:
ISBN:
Category : Leading edges (Aerodynamics)
Languages : en
Pages : 60
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Book Description
Several control techniques have been applied in order to control leading-edge vortices at high angle of attack. The purpose of these control techniques is to influence the strength and structure of the vortices, to generate rolling moment, and to delay vortex breakdown. Since the vorticity of the leading-edge vortices originates from the separation point along the leading-edge, control of development of the shear layer has been chosen as a control strategy in several investigations: blowing and suction in the tangential direction along a rounded leading-edge.
Author: Anthony M. Mitchell
Publisher:
ISBN: 9781423535225
Category :
Languages : en
Pages : 380
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Demands for more maneuverable and stealthy air vehicles have encouraged the development of new control concepts for separated flows. The goalof this research is the control of leading-edge vortex breakdown by open-loop, along-the-core blowing near the apex of a delta wing to improve lift and maneuverability at high angles of attack. Control is dependent on the knowledge of and the ability to detect principle characteristics of the phenomena. Therefore, an experimental study of a 700 delta wing was accomplished to better understand the physical properties of the vortical flow and the vortex breakdownphenomena. Multiple experimental methods were used to characterize the flow field and its influence on the model's surfaces as well as to identify parameters for closed-loop feedback control.
Author: K. T. Lee
Publisher:
ISBN:
Category : Airplanes
Languages : en
Pages : 178
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Author: National Aeronautics and Space Adm Nasa
Publisher:
ISBN: 9781731351593
Category :
Languages : en
Pages : 162
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The vortical flow over a delta wing contributes an important part of the lift - the so called nonlinear lift. Controlling this vortical flow with its favorable influence would enhance aircraft maneuverability at high angle of attack. Several previous studies have shown that control of the vortical flow field is possible through the use of blowing jets. The present experimental research studies vortical flow control by applying a new blowing scheme to the rounded leading edge of a delta wing; this blowing scheme is called Tangential Leading Edge Blowing (TLEB). Vortical flow response both to steady blowing and to unsteady blowing is investigated. It is found that TLEB can redevelop stable, strong vortices even in the post-stall angle of attack regime. Analysis of the steady data shows that the effect of leading edge blowing can be interpreted as an effective change in angle of attack. The examination of the fundamental time scales for vortical flow re-organization after the application of blowing for different initial states of the flow field is studied. Different time scales for flow re-organization are shown to depend upon the effective angle of attack. A faster response time can be achieved at angles of attack beyond stall by a suitable choice of the initial blowing momentum strength. Consequently, TLEB shows the potential of controlling the vortical flow over a wide range of angles of attack; i.e., in both for pre-stall and post-stall conditions. Lee, K. T. and Roberts, Leonard BLOWING; DELTA WINGS; FLOW DISTRIBUTION; LEADING EDGES; VORTICES; AIRCRAFT MANEUVERS; ANGLE OF ATTACK; MOMENTUM; NONLINEARITY; STABILITY...
Author: Edward C. Polhamus
Publisher:
ISBN:
Category : Delta wing airplanes
Languages : en
Pages : 18
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Author: Jacob A. Freeman
Publisher:
ISBN: 9781423504412
Category : Delta wing airplanes
Languages : en
Pages : 172
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Using the commercially available FLUENT 3-D flow field solver, this research effort investigated vortex breakdown over a delta wing at high angle of attack (a) in preparation for investigation of active control of vortex breakdown using steady, along- core blowing A flat delta-shaped half-wing with sharp leading edge and sweep angle of 600 was modeled at a 180 in a wind tunnel at Mach 0,04 and Reynolds number of 3,4 x 10(sub 5). A hybrid (combination of structured and unstructured) numerical mesh was generated to accommodate blowing ports on the wing surface. Results for cases without and with along-core blowing included comparison of various turbulence models for predicting both flow field physics and quantitative flow characteristics, FLUENT turbulence models included Spalart-Allmaras (S-A), Renormalization Group k-e, Reynolds Stress (RSM), and Large Eddy Simulation (LES), as well as comparison with laminar and inviscid models. Mesh independence was also investigated, and solutions were compared with experimentally determined results and theoretical prediction, These research results show that, excepting the LES model for which the computational mesh was insufficiently refined and which was not extensively investigated, none of the turbulence models above, as implemented with the given numerical grid, generated a solution which was suitably comparable to the experimental data. Much more work is required to find a suitable combination of numerical grid and turbulence model.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 8
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The overall objective of this research program was to characterize the unsteady flow structure on wings having swept edges. Wings were subjected to global control, involving motion of the entire wing, and local control, involving perturbations at specified locations on the surface of the wing. New types of experimental facilities and image acquisition and processing techniques have allowed determination of the instantaneous vorticity distributions and streamline patterns of the flow. The occurrence of vortex breakdown and stall and their phase shifts relative to the wing motion and to control at the leading-edges have been interpreted in terms of new flow mechanisms. Delta Wings, Vortex Breakdown, Laser Diagnostics.
Author: Yong Liu
Publisher:
ISBN:
Category : Delta wing airplanes
Languages : en
Pages : 28
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In this paper, the reactive flow control of delta wing leading edge vortices using along-core pulse width modulation (PWM) flow injection is presented. Leading edge vortices on the upper surface of a delta wing can augment lift. Manipulating breakdown points of leading edge vortices can effectively change the delta wing's lift and drag and generate attitude control torque. In this paper, a dynamic model of active flow control of vortex break down points is identified from wind tunnel data using a model scheduling method. Based on the identified model, a closed-loop active flow controller is developed. Simulation and real-time wind tunnel test show that the closed-loop controller can effectively manipulate the upper surface pressure of the delta wing, which indicates the closed-loop controller can effectively control vortex breakdown points.
