Download or read book Experiments in Pipe Flows at Transitional and Very High Reynolds Numbers written by Emir Öngüner and published by Cuvillier Verlag. This book was released on 2018-05-02 with total page 162 pages. Available in PDF, EPUB and Kindle. Book excerpt: The present work aims at investigating the turbulence in pipe flow. Experiments have been performed in two unique pipe facilities: CoLaPipe (CottbusLarge-Pipe) and CICLoPE (Center for International Cooperation in Long Pipe Experiments). The first part of the thesis is focusing on the development of flow considering pressure fluctuations measured along the axial direction to find the location where the flow becomes fully developed turbulent. Results show that application of ring disturbance to the incoming flow initiates turbulence much earlier upstream. The second aim of the thesis is determining the streamwise lengths of large-scale structures in fully developed turbulent state with respect to their wavenumber dependency and spatial correlation using hot-wire anemometry and Particle Image Velocimetry. Meandering structures usually referred as VLSM (very large-scale motions), have been identified with claimed extension up to 20R, where R is the pipe radius. The location of the outer spectral peaks (OSP) which represent the largest energy content per wavenumber outside the viscous wall region is moving towards to the wall as the Reynolds number increases.
Download or read book Laminar to turbulent transition in pipe flow through puffs and slugs written by Mina Nishi and published by Sudwestdeutscher Verlag Fur Hochschulschriften AG. This book was released on 2009-08 with total page 132 pages. Available in PDF, EPUB and Kindle. Book excerpt: A classical problem in fluid mechanics, laminar to turbulent transition in pipe flow, was investigated. Transition in pipe flow was first studied in detail by Reynolds (1883) and continued subsequently by numerous researchers. Nevertheless, there are still number of unknown issues that need clarification. As is well known, two distinct types of flow structure exist during a laminar to turbulent transition in pipes, namely puffs and slugs, termed by Wygnanski (1973). Investigations described in this dissertation were concentrated in the development of puffs and slugs in a pipe at different Reynolds numbers, following some preliminary research works. Also considered is a transformation from puffs to slugs through puff splittings, occurring while they propagate in a pipe or by an increase in Reynolds number. In low Reynolds number pipe flows, a dissipation of puffs was observed and then investigated. The time between when puffs were created and dissipated was termed `full- lifetime' and measured directly by a pressure transient. According to the investigations, possible evolutions of puffs were found and discussed.
Download or read book Experiments on Transitional Oscillatory Pipe Flow written by B. R. Ramaprian and published by . This book was released on 1979 with total page 115 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fully developed oil flow in a smooth circular pipe at a mean Reynolds number of about 2100 was subjected to a nominally sinusoidal flow modulation at frequencies ranging from 0.05 - 1.75 Hz. It was observed that flow oscillation increased the critical Reynolds number and, under certain conditions, even brought about laminarization of the flow, which would be intermittently turbulent at the mean Reynolds number under quasi-steady (infinitely small oscillation frequency) conditions. The occurrence and extent of laminarization was, however, found to depend on factors such as the intermittency of turbulent puffs in the mean quasi-steady flow, frequency of oscillation, etc. Two series of experiments were performed. In one series, the oscillatory flow was almost completely laminarized. In the other series, the oscillatory flow was fully turbulent. In both the cases, instantaneous velocities in the flow were measured using Laser Doppler anemometry. The instantaneous velocity was decomposed into time-mean, periodic and random components employing ensemble averaging techniques. The experiments indicated that the laminarized oscillatory flow behaves very similar to laminar oscillatory flow at either end of the Strouhal number range studied. The oscillatory turbulent flow was found to depend on both the Strouhal number and the ratio of the oscillation frequency to some characteristic frequency of turbulence in the flow in the flow. (Author).
Download or read book Investigation of High Reynolds Number Pipe Flow written by Franziska König and published by Cuvillier Verlag. This book was released on 2015-07-21 with total page 164 pages. Available in PDF, EPUB and Kindle. Book excerpt: Untersuchungen an Rohrströmungen bei hohen Reynoldszahlen sind bis heute eine große Herausforderung aufgrund der komplexen Mechanismen, die innerhalb turbulenter Rohrströmung auftreten. Daher ist es notwendig geeignete Experimente zu etablieren, um turbulente dynamische Prozesse aufzulösen und somit das Wissen zur Verfügung zu stellen, diese vollständig zu verstehen. Aufgrund dessen beschäftigt sich die vorliegende Dissertation mit der Konzeptionierung und dem Aufbau eines neuen Rohrwindkanals mit dem Fokus auf hohen Reynoldszahlen. Außerdem umfasst diese Arbeit erste experimentelle Untersuchungen und Ergebnisse. Diese zeigen, dass die neu konzipierte und aufgebaute Anlage geeignet ist, um eben diese Untersuchungen zur Turbulenz durchzuführen. Diese Aussage kann anhand intensiver Studien zum Verhalten der Einlauflange in Rohrströmungen bei verschiedenen Randbedingungen bestätigt werden. Weiterführende Experimente zur Bestimmung der Wandschubspannung unter Einbeziehung verschiedener Methoden haben gezeigt, dass an dieser Stelle große Schwierigkeiten und damit Abweichungen der Ergebnisse auftreten. Das wiederum spiegelt sich direkt im Skalierungsverhalten der Hauptströmungs- und Schwankungsgeschwindigkeit wieder. Neben der Einführung der neuen CoLaPipe und der Diskussion der ersten Ergebnisse beinhaltet diese Dissertation eine umfassende Literaturrecherche.
Download or read book Experiments in High Reynolds Number Turbulent Pipe Flow written by M. V. Zagarola and published by . This book was released on 1996 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Study of Turbulent Flow in Rough Pipes written by James Mueller Robertson and published by . This book was released on 1965 with total page 144 pages. Available in PDF, EPUB and Kindle. Book excerpt: The considerable literature on turbulent flow past rough surfaces is correlated in terms of modes of presenting the smooth-to-rough transition and the influences of roughness density and shape. Flow measurements in a 3 in. smooth and sand roughened pipe and in an 8 in. steel pipe with 'natural' roughness are reported. The temporal-mean velocity and friction measurements show transitional (between smooth and fully rough behavior) variations. The pipe factor variation is also elucidated; the sand-roughened pipe studies indicate a shift in Nikuradse's presentation. The turbulence - as intensity divided by shear velocity and macroscale in ratio to pipe radius - in rough pipe flow appears the same in rough as in smooth pipe flow. The relative turbulence intensity is constant, or at most decreases slowly with increase in flow Reynolds number. (Author).
Download or read book Flow Control Techniques and Applications written by Jinjun Wang and published by Cambridge University Press. This book was released on 2019 with total page 293 pages. Available in PDF, EPUB and Kindle. Book excerpt: Master the theory, applications and control mechanisms of flow control techniques.
Download or read book Investigation of High Reynolds Number Pipe Flow written by Franziska König and published by . This book was released on 2016-03 with total page 142 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book An Experimental Study of Oscillatory Pipe Flow at Transitional Reynolds Number written by Shuen-Wei Tu and published by . This book was released on 1978 with total page 296 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Transition from Turbulent to Laminar Pipe Flow written by Merwin Sibulkin and published by . This book was released on 1961 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt: An experimental investigation of low speed pipe flow was conducted for an initially turbulent flow of air. At subcritical Reynolds numbers, as the fluid travelled downstream its velocity profile approached the parabolic distribution corresponding to laminar flow; the rate of transition towards laminar flow being more rapid at lower Reynolds numbers. Concurrent hot-wire-anemometer measurements showed a corresponding dependence on Reynolds number of the rate of decay of the longitudinal velocity fluctuations. These velocity fluctuations were also found to decay more rapidly near the wall and center of the pipe than at intermediate radii. The energy spectrum of the fluctuations was measured along the pipe centerline, and, in terms of the macroscale, these spectra were similar. (Author).
Download or read book Current Hydraulic Laboratory Research in the United States written by and published by . This book was released on 1970 with total page 360 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book NBS Special Publication written by and published by . This book was released on 1968 with total page 540 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Hydraulic Research in the United States and Canada written by United States. National Bureau of Standards and published by . This book was released on 1978 with total page 384 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Report written by United States. National Bureau of Standards and published by . This book was released on 1968 with total page 696 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Hydraulic Research in the United States 1970 written by United States. National Bureau of Standards and published by . This book was released on 1971 with total page 360 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Hydraulic Research in the United States 1968 written by United States. National Bureau of Standards and published by . This book was released on 1969 with total page 342 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fluid Flow Phenomena written by Paolo Orlandi and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 369 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book deals with the simulation of the incompressible Navier-Stokes equations for laminar and turbulent flows. The book is limited to explaining and employing the finite difference method. It furnishes a large number of source codes which permit to play with the Navier-Stokes equations and to understand the complex physics related to fluid mechanics. Numerical simulations are useful tools to understand the complexity of the flows, which often is difficult to derive from laboratory experiments. This book, then, can be very useful to scholars doing laboratory experiments, since they often do not have extra time to study the large variety of numerical methods; furthermore they cannot spend more time in transferring one of the methods into a computer language. By means of numerical simulations, for example, insights into the vorticity field can be obtained which are difficult to obtain by measurements. This book can be used by graduate as well as undergraduate students while reading books on theoretical fluid mechanics; it teaches how to simulate the dynamics of flow fields on personal computers. This will provide a better way of understanding the theory. Two chapters on Large Eddy Simulations have been included, since this is a methodology that in the near future will allow more universal turbulence models for practical applications. The direct simulation of the Navier-Stokes equations (DNS) is simple by finite-differences, that are satisfactory to reproduce the dynamics of turbulent flows. A large part of the book is devoted to the study of homogeneous and wall turbulent flows. In the second chapter the elementary concept of finite difference is given to solve parabolic and elliptical partial differential equations. In successive chapters the 1D, 2D, and 3D Navier-Stokes equations are solved in Cartesian and cylindrical coordinates. Finally, Large Eddy Simulations are performed to check the importance of the subgrid scale models. Results for turbulent and laminar flows are discussed, with particular emphasis on vortex dynamics. This volume will be of interest to graduate students and researchers wanting to compare experiments and numerical simulations, and to workers in the mechanical and aeronautic industries.
