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Book Experimental Investigation of Turbulent Shear Flows

Download or read book Experimental Investigation of Turbulent Shear Flows written by Wen Shiuh Hwang and published by . This book was released on 1971 with total page 260 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Experimental Investigation of Turbulent Boundary Layer with Uniform Blowing at Moderate and High Reynolds Numbers

Download or read book Experimental Investigation of Turbulent Boundary Layer with Uniform Blowing at Moderate and High Reynolds Numbers written by Gazi Hasanuzzaman and published by Cuvillier Verlag. This book was released on 2022-01-18 with total page 180 pages. Available in PDF, EPUB and Kindle. Book excerpt: Experimental investigation in turbulent boundary layer flows represents one of the canonical geometries of wall bounded shear flows. Utmost relevance of such experiments, however, is applied in the engineering applications in aerospace and marine industries. In particular, continuous effort is being imparted to explore the underlying physics of the flow in order to develop models for numerical tools and to achieve flow control. Flow control experiments have been widely investigated since 1930’s. Several flow control technique has been explored and have shown potential benefit. But the choice of control technique depends largely on the boundary condition and the type of application. Hence, friction drag of subsonic transport aircraft is intended to be reduced within the scope of this Ph. D. topic. Therefore, application of active control method such as microblowing effect in the incompressible, zero pressure gradient turbulent boundary layer was investigated. A series of experiments have been performed in two different wind tunnel facilities. Wind tunnel from Department of Aerodynamics and Fluid Mechanics (LAS) was used for the measurements for moderate Reynolds number range in co-operation with the wind tunnel from Laboratoire de M´ecanique de Feiret Lille for large Reynolds number range. Measurements are conducted with the help of state-of-the-art techniques such as Laser Doppler Anemometry, Particle Image Velocimetry and electronic pressure sensors.

Book Turbulent Shear Flows I

Download or read book Turbulent Shear Flows I written by F. Durst and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 415 pages. Available in PDF, EPUB and Kindle. Book excerpt: The present book contains papers that have been selected from contributions to the First International Symposium on Turbulent Shear Flows which was held from the 18th to 20th April 1977 at The Pennsylvania State University, University Park, Pennsylvania, USA. Attend ees from close to 20 countries presented over 100 contributions at this meeting in which many aspects of the current activities in turbulence research were covered. Five topics received particular attention at the Symposium: Free Flows Wall Flows Recirculating Flows Developments in Reynolds Stress Closures New Directions in Modeling This is also reflected in the five chapters of this book with contributions from research workers from different countries. Each chapter covers the most valuable contributions of the conference to the particular chapter topic. Of course, there were many additional good con tributions to each subject at the meeting but the limitation imposed on the length of this volume required that a selection be made. The realization of the First International Symposium on Turbulent Shear Flows was p- sible by the general support of: U. S. Army Research Office U. S. Navy Research Office Continuing Education Center of The Pennsylvania State University The conference organization was carried out by the organizing committee consisting of: F. Durst, Universitat Karlsruhe, Karlsruhe, Fed. Rep. of Germany V. W. Goldschmidt, Purdue University, West Lafayette, Ind. , USA B. E. Launder, University of California, Davis, Calif. , USA F. W. Schmidt, Pennsylvania State University, University Park, Penna.

Book An Experimental Investigation of the Flow Structure of the Turbulent Boundary Layer

Download or read book An Experimental Investigation of the Flow Structure of the Turbulent Boundary Layer written by Peter W. Runstadler and published by . This book was released on 1963 with total page 326 pages. Available in PDF, EPUB and Kindle. Book excerpt: A combination of visual and quantitative measurements is presented, providing a physical picture of the turbulent boundary layer flow structure on a flat plate. The flow structure is shown to consist of three zones, each zone has a one to one correspondence to the well known regions of the u+, y+ mean velocity profile. A wall layer region is shown to exist below y+ = 10. An apparently fully turbulent region exists corresponding to the logarithmic ''law of the wall'' and the ''buffer'' region. An intermittent zone appears to agree closely with the ''wake'' deviation region. An entirely new result of the investigation is the delineation of the structure of the wall layer region. This region is shown to contain a relatively regular structure of low and high velocity fluid streaks alternating in the span direction, together with the ejection of low momentum fluid into the outer flow. Correlations are given for the rate of ejection and the streak spacing. A qualitative description of other features of the wall layer region and the character of the remainder of the boundary layer flow structure is presented. (Author).

Book An Experimental Investigation of Mixing in Two dimensional Turbulent Shear Flows with Applications to Diffusion limited Chemical Reactions

Download or read book An Experimental Investigation of Mixing in Two dimensional Turbulent Shear Flows with Applications to Diffusion limited Chemical Reactions written by John Harrison Konrad and published by . This book was released on 1977 with total page 220 pages. Available in PDF, EPUB and Kindle. Book excerpt: The extent of molecular mixing in several two-dimensional free turbulent shear flows was measured using a concentration probe with a frequency response of 100 kHz and a spatial resolution of 0.1 mm. The flows investigated were (i) a shear layer in which the gases on either side of the layer are of unequal density, (ii) a shear layer in which the gases on either side of the layer are of equal density, and (iii) a wake in which the gases on either side of the wake are of unequal densities. The extent of mixing was measured as a function of Reynolds number for the first case. It was found that at a critical Reynolds number the extent of molecular mixing sharply increased (25%). Power spectral density curves of the concentration time histories also indicated a marked increase in the high frequency fluctuations above this Reynolds number. A shadowgraph investigation of this phenomenon revealed that three-dimensional Taylor-type vortices whose axes of rotation are basically in the flow direction exist in the flow in addition to the two-dimensional large structures previously observed. These Taylor vortices were found to be unstable above the critical Reynolds number and were producing the increase in molecular mixing. The growth and development of the two-dimensional large structures were found to be basically unaffected by this instability. It is proposed that the fully developed turbulence of shear flows is maintained by a combination of the development of the large structures and of the coupling between the large structures and these unstable Taylor vortices.

Book An Experimental Investigation of Rotational Shear Flows with Application to Turbulent Drag reducing Surfaces and Liquids

Download or read book An Experimental Investigation of Rotational Shear Flows with Application to Turbulent Drag reducing Surfaces and Liquids written by Timothy James Hall and published by . This book was released on 1999 with total page 304 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Experimental Investigation of the Behavior of Sub Grid Scale Motions in Turbulent Shear Flow

Download or read book Experimental Investigation of the Behavior of Sub Grid Scale Motions in Turbulent Shear Flow written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-03 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt: Experiments have been carried out on a vertical jet of helium issuing into a co-flow of air at a fixed exit velocity ratio of 2.0. At all the experimental conditions studied, the flow exhibits a strong self excited periodicity. The natural frequency behavior of the jet, the underlying fine-scale flow structure, and the transition to turbulence have been studied over a wide range of flow conditions. The experiments were conducted in a variable pressure facility which made it possible to vary the Reynolds number and Richardson number independently. A stroboscopic schlieren system was used for flow visualization and single-component Laser Doppler Anemometry was used to measure the axial component of velocity. The flow exhibits several interesting features. The presence of co-flow eliminates the random meandering typical of buoyant plumes in a quiescent environment and the periodicity of the helium jet under high Richardson number conditions is striking. Under these conditions transition to turbulence consists of a rapid but highly structured and repeatable breakdown and intermingling of jet and freestream fluid. At Ri = 1.6 the three-dimensional structure of the flow is seen to repeat from cycle to cycle. The point of transition moves closer to the jet exit as either the Reynolds number or the Richardson number increases. The wavelength of the longitudinal instability increases with Richardson number. At low Richardson numbers, the natural frequency scales on an inertial time scale. At high Richardson number the natural frequency scales on a buoyancy time scale. The transition from one flow regime to another occurs over a narrow range of Richardson numbers from 0.7 to 1. A buoyancy Strouhal number is used to correlate the high Richardson number frequency behavior. Cantwell, Brian Ames Research Center NAG2-382...

Book An Experimental Investigation of the Flow Structure of the Turbulent Boundary Layer

Download or read book An Experimental Investigation of the Flow Structure of the Turbulent Boundary Layer written by P. W. Runstadler and published by . This book was released on 1963 with total page 346 pages. Available in PDF, EPUB and Kindle. Book excerpt: A combination of visual and quantitative measurements is presented, providing a physical picture of the turbulent boundary layer flow structure on a flat plate. The flow structure is shown to consist of three zones, each zone has a one to one correspondence to the well known regions of the u+, y+ mean velocity profile. A wall layer region is shown to exist below y+ = 10. An apparently fully turbulent region exists corresponding to the logarithmic ''law of the wall'' and the ''buffer'' region. An intermittent zone appears to agree closely with the ''wake'' deviation region. An entirely new result of the investigation is the delineation of the structure of the wall layer region. This region is shown to contain a relatively regular structure of low and high velocity fluid streaks alternating in the span direction, together with the ejection of low momentum fluid into the outer flow. Correlations are given for the rate of ejection and the streak spacing. A qualitative description of other features of the wall layer region and the character of the remainder of the boundary layer flow structure is presented. (Author).

Book Experimental Investigation of Thermal Diffusion Effects in Laminar and Turbulent Shear Flow

Download or read book Experimental Investigation of Thermal Diffusion Effects in Laminar and Turbulent Shear Flow written by Hans Thomann and published by . This book was released on 1964 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt: An experimental investigation was conducted to determine the order of magnitude of thermal diffusion across a laminar and a turbulent shear layer. A short length of a cooled free jet was passed through stationary gas and subsequently recaptured into a continuous circulating system. Various mixtures of helium and nitrogen were investigated. With temperatures of 78K in the jet and 310K in the surrounding chamber, steady-state helium concentrations in the laminar jet were as much as 7 per cent smaller than in the surroundings. The experimental results are in good agreement with a simplified analysis. With a turbulent sheat layer between the jet and surroundings, the helium concentration inside the jet increases to within 0.1 per cent higher than the chamber level. The thermal diffusion ratio (i.e. thermal to mass concentration diffusion coefficients) in the turbulent shear layer was thus at least two orders of magnitude smaller than in the laminar case and of opposite sign. It is suggested that similar separation effects are to be expected for other steady flows with closed streamlines, such as base flows and flows past cavities. (Author).