Download or read book Structure of 2 D and 3 D Turbulent Boundary Layers with Sparsely Distributed Roughness Elements written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The present study deals with the effects of sparsely distributed three-dimensional elements on two-dimensional (2-D) and three-dimensional (3-D) turbulent boundary layers (TBL) such as those that occur on submarines, ship hulls, etc. This study was achieved in three parts: Part 1 dealt with the cylinders when placed individually in the turbulent boundary layers, thereby considering the effect of a single perturbation on the TBL; Part 2 considered the effects when the same individual elements were placed in a sparse and regular distribution, thus studying the response of the flow to a sequence of perturbations; and in Part 3, the distributions were subjected to 3-D turbulent boundary layers, thus examining the effects of streamwise and spanwise pressure gradients on the same perturbed flows as considered in Part 2. The 3-D turbulent boundary layers were generated by an idealized wing-body junction flow. Detailed 3-velocity-component Laser-Doppler Velocimetry (LDV) and other measurements were carried out to understand and describe the rough-wall flow structure. The measurements include mean velocities, turbulence quantities (Reynolds stresses and triple products), skin friction, surface pressure and oil flow visualizations in 2-D and 3-D rough-wall flows for Reynolds numbers, based on momentum thickness, greater than 7000. Very uniform circular cylindrical roughness elements of 0.38mm, 0.76mm and 1.52mm height (k) were used in square and diagonal patterns, yielding six different roughness geometries of rough-wall surface. For the 2-D rough-wall flows, the roughness Reynolds numbers, based on the element height (k) and the friction velocity, range from 26 to 131. Results for the 2-D rough-wall flows reveal that the velocity-defect law is similar for both smooth and rough surfaces, and the semi-logarithmic velocity-distribution curve is shifted by an amount depending on the height of the roughness element, showing that this amount is a function of roughness Reynolds number and the wall geometry.
Download or read book Some Effects of Sparsely Distributed Three dimensional Roughness Elements on Two dimensional Turbulent Boundary Layers written by Jacob George and published by . This book was released on 2000 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Three dimensional Turbulent Boundary Layers written by O. Sendstad and published by . This book was released on 1992 with total page 130 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Effects of Spacing and Geometry of Distributed Roughness Elements on a Two Dimensional Turbulent Boundary Layer written by and published by . This book was released on 2005 with total page 198 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis is a study of the effects of distributed roughness elements on a two-dimensional turbulent boundary layer. Measurements were taken on a total of ten rough wall configurations: four involving Gaussian spikes, and six with circular cylindrical posts. Rough wall flows are particularly suited to study with Laser Doppler Velocimetry (LDV) due to the fact that measurements are required near a solid surface, as well has in highly turbulent fluid. The LDV system used in this study is a fine resolution (50pm), three-component, fiber-optic system. All mean velocities, Reynolds stresses, and triple products are measured. This study is unique in the range and variety of roughness cases for which data was taken. The data show that flow over a rough wall is characterized by high levels of turbulence near the roughness element peaks at the interface between low-speed, near-wall fluid and the higher speed fluid above. Behind an element, high-momentum fluid sweeps toward the wall, and there is a small region of ejection of low-momentum fluid. Cylindrical elements typically have larger magnitudes of turbulent stresses at their peaks compared to Gaussian elements. Trends in mean velocity profile parameters such as displacement height, roughness effect, and wake parameter are examined with respect to roughness element geometry and spacing.
Download or read book Experimental Study of a Three dimensional Shear driven Turbulent Boundary Layer with Streamwise Adverse Pressure Gradient written by David Michael Driver and published by . This book was released on 1989 with total page 268 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book AIAA Aerospace Sciences Meeting and Exhibit 42nd written by and published by . This book was released on 2004 with total page 620 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Numerical Study of a Three dimensional Turbulent Boundary Layer written by Parviz Moin and published by . This book was released on 1990 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Effects of Steady Three dimensional Perturbations in Boundary Layers written by Raymond Sedney and published by . This book was released on 1974 with total page 56 pages. Available in PDF, EPUB and Kindle. Book excerpt: The primary purpose of this report is to survey the available information mainly experimental, on the subject. Most attention is given to the complex flow field resulting when a 3-D protuberance is introduced into a laminar boundary layer; less can be said about the turbulent case or 2-D protuberances because enough detailed, careful experiments have not been made. There are some features of the induced flow fields common to all speed ranges; applications range from flow in the atmospheric boundary layer to hypersonic vehicle problems. Some attempts to analyze the downstream flow are also summarized.
Download or read book 41st AIAA Aerospace Sciences Meeting Exhibit written by and published by . This book was released on 2003 with total page 840 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book 40th AIAA Aerospace Sciences Meeting Exhibit written by and published by . This book was released on 2002 with total page 708 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Near Wall Mechanics of Three dimensional Turbulent Boundary Layers written by Olav Sendstad and published by . This book was released on 1992 with total page 146 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Study of Turbulent Boundary Layer Structure written by John Leask Lumley and published by . This book was released on 1986 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Experimental Studies in Three dimensional Turbulent Boundary Layers written by J. P. Johnston and published by . This book was released on 1976 with total page 62 pages. Available in PDF, EPUB and Kindle. Book excerpt: The various methods for measurement of the six components of the turbulence stress tensor are reviewed, and some of the data on the turbulent shear stress vector are presented to demonstrate the validity of current ideas for.
Download or read book Turbulent Boundary Layers written by Helmut E. Weber and published by . This book was released on 1979 with total page 260 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Three Dimensional Structure of Transitional Boundary Layers written by and published by . This book was released on 1990 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: Experiments were performed of boundary layers undergoing instabilities and transition to turbulence. The experiments used multiple hotwire anemometer techniques to study the origin and evolution of the characteristic large-scale structures of transitional boundary layers. Fundamental transition mechanisms, the control of random background disturbances, and the receptivity of the boundary layer to external disturbances that lead to transition were studied. This work lays the foundation for more advanced work in boundary-layer transition and control with sound and 3-D roughness.
Download or read book A Three dimensional Single Roughness Element in a Turbulent Boundary Layer written by Henry W. Tieleman and published by . This book was released on 1965 with total page 21 pages. Available in PDF, EPUB and Kindle. Book excerpt: An investigation of the influence of a single roughness element (sphere) in a turbulent boundary layer of a smooth flat plate is reported. The pressure distribution around the surface of the sphere was measured. Integration of the pressure distribution was used to compute the drag and lift forces on the element. Measurements of the mean and turbulent velocity distributions in the boundary-layer behind the sphere were made. (Author).
Download or read book Dissertation Abstracts International written by and published by . This book was released on 2005 with total page 768 pages. Available in PDF, EPUB and Kindle. Book excerpt:
