Computational Fluid Dynamics Investigation Of Vortex Breakdown For A Delta Wing At High Angle Of Attack
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| Author | : Jacob A. Freeman |
| Publisher | : |
| Total Pages | : 172 |
| Release | : 2003-03-01 |
| Genre | : Delta wing airplanes |
| ISBN | : 9781423504412 |
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 | : |
| Total Pages | : 43 |
| Release | : 1994 |
| Genre | : |
| ISBN | : |
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 | : Xing Z. Huang |
| Publisher | : Springer Verlag |
| Total Pages | : 516 |
| Release | : 2008-10-01 |
| Genre | : Science |
| ISBN | : 9781402093326 |
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 | : David M. Richwine |
| Publisher | : |
| Total Pages | : 56 |
| Release | : 1992 |
| Genre | : Research aircraft |
| ISBN | : |
| Author | : Robert William MacCormack |
| Publisher | : World Scientific |
| Total Pages | : 528 |
| Release | : 2002 |
| Genre | : Technology & Engineering |
| ISBN | : 9789812810793 |
This series of volumes on the OC Frontiers of Computational Fluid DynamicsOCO was introduced to honor contributors who have made a major impact on the field. The first volume was published in 1994 and was dedicated to Prof Antony Jameson; the second was published in 1998 and was dedicated to Prof Earl Murman. The volume is dedicated to Prof Robert MacCormack. The twenty-six chapters in the current volume have been written by leading researchers from academia, government laboratories, and industry. They present up-to-date descriptions of recent developments in techniques for numerical analysis of fluid flow problems, and applications of these techniques to important problems in industry, as well as the classic paper that introduced the OC MacCormack schemeOCO to the world. Contents: The Effect of Viscosity in Hypervelocity Impact Cratering (R W MacCormack); The MacCormack Method OCo Historical Perspective (C M Hung et al.); Numerical Solutions of Cauchy-Riemann Equations for Two and Three Dimensional Flows (M M Hafez & J Houseman); Extension of Efficient Low Dissipation High Order Schemes for 3-D Curvilinear Moving Grids (M Vinokur & H C Yee); Scalable Parallel Implicit Multigrid Solution of Unsteady Incompressible Flows (R Pankajakshan et al.); Lattice Boltzmann Simulation of Incompressible Flows (N Satofuka & M Ishikura); Numerical Simulation of MHD Effects on Hypersonic Flow of a Weakly Ionized Gas in an Inlet (R K Agarwal & P Deb); Development of 3D DRAGON Grid Method for Complex Geometry (M-S Liou & Y Zheng); Advances in Algorithms for Computing Aerodynamic Flows (D W Zingg et al.); Selected CFD Capabilities at DLR (W Kordulla); CFD Applications to Space Transportation Systems (K Fujii); Information Science OCo A New Frontier of CFD (K Oshima & Y Oshima); Integration of CFD into Aerodynamics Education (E M Murman & A Rizzi); and other papers. Readership: Researchers and graduate students in numerical and computational mathematics."
| Author | : Devin O. O'Dowd |
| Publisher | : |
| Total Pages | : 66 |
| Release | : 1999-02-01 |
| Genre | : Airplanes |
| ISBN | : 9781423554370 |
The study of vortex breakdown over delta wings at high angles of attack (AOA) has been an interest to researchers, mathematicians, and aircraft designers for decades. It is a very hot topic as it relates to many aircraft being designed today and because no complete understanding exists. Most of the understanding that does exist comes in the form of the problems associated with vortex breakdown. Many question if it is possible to control the breakdown to avoid the problems and to aid the aircraft in maneuverability. The purpose of this study is to lay the foundation for future research at the University of Washington, so that the identity to the cause of the vortex breakdown may be found.
| Author | : N. G. Verhaagen |
| Publisher | : |
| Total Pages | : 38 |
| Release | : 1995 |
| Genre | : |
| ISBN | : |
| Author | : Ku Zilati Ku Shaari |
| Publisher | : Springer |
| Total Pages | : 172 |
| Release | : 2014-11-28 |
| Genre | : Technology & Engineering |
| ISBN | : 3319028367 |
This volume presents the results of Computational Fluid Dynamics (CFD) analysis that can be used for conceptual studies of product design, detail product development, process troubleshooting. It demonstrates the benefit of CFD modeling as a cost saving, timely, safe and easy to scale-up methodology.
| Author | : Abdullah M. Alkhozam |
| Publisher | : |
| Total Pages | : 217 |
| Release | : 1994 |
| Genre | : |
| ISBN | : |
A flow visualization study of the vortical flow over a cropped double-delta wing model with sharp leading edges and its three derivatives with small geometric modifications (fillets) at the strake wing junction was conducted in the Naval Postgraduate School water tunnel using the dye-injection technique. The fillets increased the wing area of the baseline model by 1%. The main focus of this study was to evaluate the effect of fillets on vortex core trajectories, interactions and breakdown on the leeward surface at high angle of attack (AOA) with zero sideslip angle. Comparison of test results for different fillet shapes indicates delay in both vortex interaction and breakdown at high AOA, particularly for the diamond fillet shapes. The vortex breakdown data implies lift augmentation for both static and dynamic case, with the static data correlating well with recently published numerical data. High angle-of-attack aerodynamics, Effect of fillets on vortex core trajectories, Interaction and breakdown, Flow visualization by dye-injection technique, Static and dynamic water tunnel studies on double-delta wings.
| Author | : Raymond E. Gordnier |
| Publisher | : |
| Total Pages | : 50 |
| Release | : 1993 |
| Genre | : Airplanes |
| ISBN | : |
This report presents computations of the flowfield around an 80 degree sweep delta wing undergoing a constant roll-rate maneuver from 0 to 45 degrees. The governing equations for the problem are the unsteady, three- dimensional Navier-Stokes equations. The equations are solved using the implicit, approximately-factored algorithm of Beam-Warming. Fixed roll angle results are also presented and compared with experimental measurements to demonstrate the ability of the numerical technique to accurately capture the flowfield around a rolled delta wing. The dynamic behaviors of the vortex position and strength, as well as their corresponding effect on surface pressure, lift and roll moment, are described. A simple, quasi-static explanation of these vortex behaviors based on effective angle-of-attack and sideslip angle is proposed ... Delta wing roll, Vortex dynamics, Vortical flow, Unsteady maneuver.
