An Experimental Study Of The Unsteady Nature Of Vortex Breakdown Over Delta Wings
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Author | : Matthew S. Menke |
Publisher | : |
Total Pages | : 182 |
Release | : 1996 |
Genre | : |
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Download An Experimental Study of the Unsteady Nature of Vortex Breakdown Over Delta Wings Book in PDF, Epub and Kindle
Author | : Houbin Yang |
Publisher | : |
Total Pages | : 208 |
Release | : 1996 |
Genre | : |
ISBN | : |
Download Unsteady Nature of Vortex Breakdown Over Delta Wings and Its Control Book in PDF, Epub and Kindle
Author | : |
Publisher | : |
Total Pages | : 8 |
Release | : 1994 |
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Download Unsteady Structure of Leading-Edge Vortices on a Delta Wing Book in PDF, Epub and Kindle
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 | : José L. Stevens |
Publisher | : |
Total Pages | : 142 |
Release | : 1996 |
Genre | : Aerodynamics |
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Download Experimental Study of Vortex Breakdown in a Cylindrical, Swirling Flow Book in PDF, Epub and Kindle
Author | : Anthony M. Mitchell |
Publisher | : |
Total Pages | : 380 |
Release | : 2000-08-01 |
Genre | : |
ISBN | : 9781423535225 |
Download Characterization and Control of Vortex Breakdown Over a Delta Wing at High Angles of Attack Book in PDF, Epub and Kindle
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 | : Hank I-Hung Lin |
Publisher | : |
Total Pages | : 370 |
Release | : 1998 |
Genre | : |
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Download Vortex Breakdown Over Delta Wings in an Unsteady Free Stream Book in PDF, Epub and Kindle
Author | : Xing Z. Huang |
Publisher | : Springer Verlag |
Total Pages | : 516 |
Release | : 2008-10-01 |
Genre | : Science |
ISBN | : 9781402093326 |
Download Vortex Flow Behavior Over Slender Delta Wing Configurations Book in PDF, Epub and Kindle
The book discusses the behavior of vortices over sharp and highly swept wing configurations used for current and future military aircraft. Special attention is paid to the effects of critical flow phenomenon such as vortex breakdown occuring at high angles of attack or high angular rates. The wind tunnel experiments conducted on delta-wing configurations in wind tunnels in Canada, Europe, Russia and the United States are given in eight chapters. The experiments provide an extended data base that gives insight into the effects of the angle of attack, angular rate, Reynolds number and Mach number on the behavior of vortices over several slender delta wings in stationary and instationary flights. A critical assessment is given in a separated chapter of the available experimental data bases and out of these data, one and the same data set is selected for the validation and verification of analytical and numerical solutions.Comprehansive computational results are given in another ten chapters. Steady-state and time-accurate solutions for the steady and unsteady flow over the selected delta-wing configuration are discussed. These solutions are generated using structured and unstructured grid methods.The analytical solutions for the flow over a delta wing are discussed and compared with experimental data in three more chapters.In the final chapter a validation and verification of the analytical and CFD solutions is given.
Author | : |
Publisher | : |
Total Pages | : 87 |
Release | : 1995 |
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Download Vortex Breakdown Over Unsteady Wings and Its Control Book in PDF, Epub and Kindle
Control of vortex breakdown continues to be of vital importance because the breakdown may have a considerable effect on aircraft performance, such as the effect on the time-averaged lift force (Lee and Ho, 1990). Breakdown is also important because of the unsteady nature of flow downstream of vortex breakdown. The unsteadiness may affect the stability of the aircraft and also cause buffeting. The objectives of this work are to understand the physics of unsteady flow phenomena in vortex breakdown region, and to develop techniques for active (feedback) and passive (open loop) control of vortex breakdown over steady and unsteady delta wings.
Author | : Mohammad Reza Soltani |
Publisher | : |
Total Pages | : 506 |
Release | : 1992 |
Genre | : |
ISBN | : |
Download An Experimental Study of the Relationship Between Forces and Moments and Vortex Breakdown on a Pitching Delta Wing Book in PDF, Epub and Kindle
Wind-tunnel experiments were performed to study the complex flow mechanisms on a 70-deg. sharp leading-edge delta wing model at both static and dynamic conditions at a Reynolds number of 1.43 $times$ 10$sp6$. Large amplitude oscillatory motions were produced by sinusoidally pitching the model over a range of reduced frequencies. Ramp motions were obtained using an initial sinusoidal increase in angle of attack and hold. Aerodynamic forces and moments were obtained from a six-component internal strain-gauge balance. In addition, smoke flow visualization was conducted to study the development, and breakdown of the leading-edge vortices under static, dynamic, and ramp conditions. The visualization experiment was performed at a Reynolds number of 0.16 $times$ 10$sp6$. Static forces compared well with previously published data. The non-linear vortex lift and the movement of the burst point over the wing surface were related to changes in the measured lift-curve slope. Asymmetrical bursting produced by testing the model at nonzero sideslip angle, had a significant influence on the magnitude of the measured forces and moments. Dynamic data varied substantially with reduced frequency. Large forces and moments overshoots, a delay in dynamic stall, and a hysteresis loop between the values of aerodynamic loads in upstroke and downstroke motion were observed. The dynamic vortex breakdown point was seen to reach the trailing-edge at a smaller angle of attack than it did when in the static case. However, at large angles of attack, its position lagged that of the static model. The magnitude of the rolling moment coefficient was strongly influenced by the reduced frequency. For the ramp motion case, aerodynamic forces and moments closely followed those of the oscillatory case during the pitch-up motion. However, upon cessation of the motion, the persistence of the dynamic effects was a strong function of the pitch rate. Terminating the motion at 24 deg. angle of attack produced lower lift and normal force values when the data were compared to their static values. This was caused by the early bursting phenomenon observed during the dynamic motion, thus reducing dynamic lift and normal force coefficients.
Author | : |
Publisher | : |
Total Pages | : 15 |
Release | : 2003 |
Genre | : |
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Download Experimental Investigation of Vortex Breakdown Over a Delta Wing with Consideration of Control by Fluid Injection Book in PDF, Epub and Kindle