Computed Unsteady Structure Of Spiral Vortex Breakdown On Delta Wings
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Author | : Miguel R. Visbal |
Publisher | : |
Total Pages | : |
Release | : 1996 |
Genre | : |
ISBN | : |
Download Computed Unsteady Structure of Spiral Vortex Breakdown on Delta Wings Book in PDF, Epub and Kindle
Author | : |
Publisher | : |
Total Pages | : 8 |
Release | : 1994 |
Genre | : |
ISBN | : |
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 | : C. Shih |
Publisher | : |
Total Pages | : |
Release | : 1996 |
Genre | : |
ISBN | : |
Download Unsteady Structure of Leading-edge Vortex Flow Over a Delta Wing 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 | : Hank I-Hung Lin |
Publisher | : |
Total Pages | : 370 |
Release | : 1998 |
Genre | : |
ISBN | : |
Download Vortex Breakdown Over Delta Wings in an Unsteady Free Stream Book in PDF, Epub and Kindle
Author | : Raymond E. Gordnier |
Publisher | : |
Total Pages | : 44 |
Release | : 1991 |
Genre | : Airplanes |
ISBN | : |
Download Computation of a Kelvin-Helmholtz Instability for Delta Wing Vortex Flows Book in PDF, Epub and Kindle
The structure of the shear layer which emanates from the leading edge of a 76 degrees sweep delta wing and forms the primary vortex is investigated numerically. The flow conditions are M at infinity = 0.2, Re = 50,000 and angle of attack of 20.5 degrees. Computational results are obtained using a Beam- Warning type algorithm. The existence of a Kelvin-Helmholtz type instability of the shear layer which emanates from the leading edge of the delta wing is demonstrated. A description is provided of the three-dimensional, unsteady behavior of the small-scale vortices associated with this instability. The numerical results are compared qualitatively with experimental flow visualizations exhibiting similar behavior.
Author | : Miguel R. Visbal |
Publisher | : |
Total Pages | : |
Release | : 1995 |
Genre | : |
ISBN | : |
Download Numerical Simulation of Spiral Vortex Breakdown Above a Delta Wing Book in PDF, Epub and Kindle
Author | : |
Publisher | : |
Total Pages | : 43 |
Release | : 1994 |
Genre | : |
ISBN | : |
Download Numerical Simulation of Transient Vortex Breakdown Above a Pitching Delta Wing Book in PDF, Epub and Kindle
Computational results are presented for transient vortex breakdown above a delta wing subject to a pitch-and-hold maneuver to high angle of attack. The flows are simulated by solving the full three-dimensional Navier-Stokes equations on a moving grid using the implicit Beam-Warming algorithm. An assessment of the effects of numerical resolution, and favorable comparison with experimental data suggest the computational approach captures the basic dynamics of this transient breakdown. The pressure gradient along the vortex axis is found to play a dominant role in the initiation of breakdown. A description of the three-dimensional instantaneous structure of the flow field is provided for the first time using critical-point theory. The reversed-flow region in the vortex core is associated with pairs of opposite spiral/saddle critical points. At its onset, the vortex breakdown is fairly axisymmetric; however, as it proceeds upstream and a stronger transition takes place along the axis, asymmetric effects become important and result in the formation of a bubble-type breakdown. This bubble structure is open and contains within itself a pair of stagnation points which are diametrically opposed and which rotate in the same sense as the base flow. Vortex breakdown, Delta wings, Unsteady aerodynamics, Computational fluid dynamics.
Author | : Matthew S. Menke |
Publisher | : |
Total Pages | : 182 |
Release | : 1996 |
Genre | : |
ISBN | : |
Download An Experimental Study of the Unsteady Nature of Vortex Breakdown Over Delta Wings Book in PDF, Epub and Kindle
Author | : Werner Haase |
Publisher | : Springer Science & Business Media |
Total Pages | : 469 |
Release | : 2009-05-12 |
Genre | : Technology & Engineering |
ISBN | : 3540927735 |
Download DESider – A European Effort on Hybrid RANS-LES Modelling Book in PDF, Epub and Kindle
Preface “In aircraft design, efficiency is determined by the ability to accurately and rel- bly predict the occurrence of, and to model the development of, turbulent flows. Hence, the main objective in industrial computational fluid dynamics (CFD) is to increase the capabilities for an improved predictive accuracy for both complex flows and complex geometries”. This text part taken from Haase et al (2006), - scribing the results of the DESider predecessor project “FLOMANIA” is still - and will be in future valid. With an ever-increasing demand for faster, more reliable and cleaner aircraft, flight envelopes are necessarily shifted into areas of the flow regimes exhibiting highly unsteady and, for military aircraft, unstable flow behaviour. This undou- edly poses major new challenges in CFD; generally stated as an increased pred- tive accuracy whist retaining “affordable” computation times. Together with highly resolved meshes employing millions of nodes, numerical methods must have the inherent capability to predict unsteady flows. Although at present, (U)RANS methods are likely to remain as the workhorses in industry, the DESider project focussed on the development and combination of these approaches with LES methods in order to “bridge” the gap between the much more expensive (due to high Reynolds numbers in flight), but more accurate (full) LES.