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| Author | : Duncan Ohno |
| Publisher | : |
| Total Pages | : 0 |
| Release | : 2023 |
| Genre | : |
| ISBN | : 9783843953634 |
| Author | : |
| Publisher | : |
| Total Pages | : 34 |
| Release | : 1984 |
| Genre | : |
| ISBN | : |
| Author | : Vallampati Ramachandra Prasad |
| Publisher | : BoD – Books on Demand |
| Total Pages | : 264 |
| Release | : 2023-02-22 |
| Genre | : Technology & Engineering |
| ISBN | : 1803562188 |
This book provides a comprehensive overview of boundary layer flows, including laminar and turbulent flows. Chapters discuss such topics as the nature of transition, the effect of two-dimensional and isolated roughness on laminar flow, and progress in the design of low-drag airfoils. They also present theoretical and experimental results in boundary layer flows and discuss directions for future research.
| Author | : J. DeRuyck |
| Publisher | : |
| Total Pages | : 102 |
| Release | : 1989 |
| Genre | : |
| ISBN | : |
Objectives of this investigation were: 1) to identify the conditions under which a sinusoidally oscillating NACA 0012 airfoil operates with a leading edge separation bubble and the conditions under which it operates with leading edge stall; 2) to conduct complete boundary layer and near wake survey in the presence of the leading edge separation bubble; and 3) to investigate the flow near the trailing edge and in the near wake while the airfoil was undergoing leading edge stall. The airfoil oscillates about an axis at 25% chord from the leading edge, with a nominal reduced frequency of 0.3 and Reynolds number of 300,000. Experiments were made at 4 to 14, 5 to 15, 6 to 16 and 8 to 18 deg angle of attack. It was found that the most probable cause of leading edge stall was due to the leading edge separation bubble burst which occurred soon after static stall limit was exceeded. Leading edge stall is not due to the rapid upstream movement of the trailing edge separation. The velocity vectors and the Reynolds stress tensors were measured using a slanted rotating single sensor hot-wire. The complete suction side boundary layer profile and the near wake was surveyed at 5-15 deg oscillation where no interaction is observed between leading edge and trailing edge flows. Keywords: Unsteady aerodynamics; Dynamic stall; High angle of attack; Flow separation; Rotorcraft; Wake; Unsteady flow transition; Belgium. (EDC).
| Author | : S. M. Belotserkovsky |
| Publisher | : CRC Press |
| Total Pages | : 322 |
| Release | : 1992-11-30 |
| Genre | : Technology & Engineering |
| ISBN | : 9780849393068 |
Two-Dimensional Separated Flows provides a systematic presentation of the theory of separated flow around bodies. The main classes of aerodynamic problems of plane-parallel flow around bodies are described, and the steady aerodynamic, unsteady aerodynamic, and statistical characteristics of a trailing wake are determined. Numerical methods based on the synthesis of models for non-viscous incompressible flow and boundary layer, algorithms, examples, and systematic comparisons are presented. The book also includes numerical results for the problem of separated flow around fixed, oscillating, and rotating cylinders, in addition to results for separated flow around an aerofoil over a wide range of angles. Two-Dimensional Separated Flows will benefit researchers and students studying aerodynamics, aircraft dynamics, aeroelasticity, and the aerodynamics of building structures.
| Author | : C. A. Meyer |
| Publisher | : |
| Total Pages | : 106 |
| Release | : 1961 |
| Genre | : Laminar flow |
| ISBN | : |
A number of aspects of transition from laminar to turbulent flow were investigated on a flat plate with free stream water velocities between .75 feet per second and 1.2 feet per second. The study was primarily visual, using dye techniques, although some measurements were made using a hot film anemometer. Also investigated were the later stages of natural transition. Dye patterns associated with the chain of events leading from laminar to turbulent flow in natural transition were analyzed. (Author).
| Author | : Laurence K. Loftin |
| Publisher | : |
| Total Pages | : 48 |
| Release | : 1946 |
| Genre | : Aerodynamic load |
| ISBN | : |
Summary: Tests were conducted with two typical low-drag airfoils of 90-inch chord to determine the effects of surface projections, grooves, and sanding scratches on boundary-layer transition. The Reynolds number at which a spanwise row of cylindrical projections would cause premature transition was determined for a range of Reynolds number from approximately 3 x 106 to 10 x 106. Data were obtained for projections of various sizes and chordwise locations on both low-drag airfoils. The results were analyzed on the assumption that the critical airfoil Reynolds number for a given projection was a function only of the local-flow conditions around the projection. This assumption neglected possible effects of tunnel turbulence, pressure gradient, boundary-layer Reynolds number, and the original extent of the laminar flow. The data correlated on the basis of this assumption within a range of critical airfoil Reynolds number of ±0.5 x 106 and within a range of projection height of ±0.002 inch. The tests of surface grooves and sanding scratches indicated that, for the range of Reynolds number investigated, the laminar boundary layer was much less sensitive to surface grooves and sanding scratches than to projections above the surface.
| Author | : Gregory S. West |
| Publisher | : |
| Total Pages | : 346 |
| Release | : 1985 |
| Genre | : Aerofoils |
| ISBN | : |
Reshotko has suggested that transition may be viewed as the response of a very complex three-dimensional nonlinear oscillator (the laminar boundary layer) to a random and often statistically nonuniform forcing function (the disturbances). The first objective of this study concerns the phenomenon of flow transition in boundary layers on turbine airfoils--from the onset of turbulence to the transition completion. Transition studies, though fundamental to fluid mechanics, are unique in gas turbine cascades because of the compounding factors that act not in individual isolation, but as a collective group and that constitute by-pass mechanisms not amenable to linear analyses from a mathematical point of view. The second objective is to evolve an engineering method to account for surface roughness effects on heat transfer and turbulent boundary layer analyses, which have heretofore been studied in fragments. Transition prediction in gas turbine boundary layer flows is critical in assessing the cooling requirements for gas turbine vanes and blades. This report summarizes the classical, fundamental findings in transition prediction for simplified geometrics and discusses empirical rules currently in use for gas turbine environments. Keywords: Airfoil boundary layer transition.
| Author | : H. Schlichting |
| Publisher | : |
| Total Pages | : 148 |
| Release | : 1949 |
| Genre | : Aerodynamics |
| ISBN | : |
The subject of turbulent flow is treated in detail. The available data on flow through pipes and over flat plates are presented. Turbulent wakes and jets are treated by means of the Prandtl mixing length theory. A section is devoted to the Gruschwitz method for calculating turbulent boundary layers in accelerated and retarded flows. The methods of Betz and Jones for determining profile drag from wake surveys are given. A chapter on the theory of the stability of the laminar boundary layer, developed from the point of view of small oscillations, is also included.
| Author | : G. V. Lachmann |
| Publisher | : Elsevier |
| Total Pages | : 768 |
| Release | : 2014-05-12 |
| Genre | : Technology & Engineering |
| ISBN | : 1483226662 |
Boundary Layer and Flow Control: Its Principles and Application, Volume 2 focuses on the layer of fluid in the immediate area of a bounding surface where the effects of viscosity are substantial. This book is organized into two main topics—boundary layer control for low drag, and shock-induced separation and its prevention by design and boundary layer control. It specifically discusses the nature of transition, effect of two-dimensional and isolated roughness on laminar flow, and progress in the design of low drag aerofoils. The onset of separation effects for aerofoils and wings, shock-induced separation for laminar boundary layers, and shock-induced separation for laminar boundary layers are also deliberated. This volume is recommended to physicists and specialists interested in boundary layer and flow control.
