Measurements with Particle Image Velocimetry on Fully Developed Turbulent Pipe Flow at Low Reynolds Number PDF Download
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Author: J. Westerweel Publisher: ISBN: Category : Languages : en Pages : 8
Book Description
Measurements with particle image velocimetry were carried out in fully developed turbulent pipe flow at a Reynolds number of 5,277. Data were obtained in a plane through the centerline of the pipe, across the full diameter. Statistical properties of the flow obtained by ensemble averaging of the data along the axial direction were in good agreement with direct numerical simulation. Maps of instantaneous tangential vorticity reveal spatial structures near the pipe wall that resemble coherent flow structures predicted by direct numerical simulation. (Author).
Author: J. Westerweel Publisher: ISBN: Category : Languages : en Pages : 8
Book Description
Measurements with particle image velocimetry were carried out in fully developed turbulent pipe flow at a Reynolds number of 5,277. Data were obtained in a plane through the centerline of the pipe, across the full diameter. Statistical properties of the flow obtained by ensemble averaging of the data along the axial direction were in good agreement with direct numerical simulation. Maps of instantaneous tangential vorticity reveal spatial structures near the pipe wall that resemble coherent flow structures predicted by direct numerical simulation. (Author).
Author: Zeinab Hallol Publisher: Cuvillier Verlag ISBN: 373696501X Category : Technology & Engineering Languages : en Pages : 146
Book Description
In this thesis, coherent turbulent structures in turbulent pipe flow are investigated at relatively high Reynolds numbers and study their association in both total kinetic energy and Reynolds shear stress. Experimental investigations have been performed in Cottbus Large Pipe test facility (CoLaPipe) for pipe flow over a wide range of Reynolds number 8 × 104 ≤ ReD ≤ 1 × 106, located at the Aerodynamics and Fluid Mechanics Department, Brandenburg University of Technology Cottbus- Senftenberg (BTU). The first part of the thesis focuses on determining the contribution of the coherent structures using one-dimensional spectral analysis and assessing the structures behaviour in the outer region of pipe flow using high spatial resolution Hot-wire measurement up to 30kHz. The results of the power and pre-multiplied spectrum of stream-wise velocity indicate that the wavelength value of very large scale motions (VLSMs) acquires 19R at a maximum Reynolds number range ReD=1 × 106 (Reτ =19000). On the other hand, large-scale motions have a wavelength value of 3R over different Reynolds number range. Regarding the identified wavelength values, it is observed that contribution to energy for structures greater than 3R carries 55% of total kinetic energy. In addition, temporal-spatial resolution using the High-speed PIV measurements has been performed in CoLaPipe to estimate the contribution magnitude of stream-wise/wall-normal velocity fluctuations to total kinetic energy and Reynolds shear stress in the logarithmic and outer layer.
Author: Emir Öngüner Publisher: Cuvillier Verlag ISBN: 3736987838 Category : Technology & Engineering Languages : en Pages : 162
Book Description
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.
Author: Christian Bauer Publisher: Cuvillier Verlag ISBN: 3736963696 Category : Technology & Engineering Languages : en Pages : 244
Book Description
Die turbulente Rohrströmung ist nicht nur von großer Bedeutung für Anwendungen im Ingenieurbereich, sondern auch für die Grundlagenforschung von wandnaher Turbulenz. In der vorliegenden Arbeit wird die Interaktion sogenannter turbulenter Superstrukturen (engl.: very-large-scale motions, VLSMs) mit der kleinskaligen Wandturbulenz auf Basis der Methode der direkten numerischen Simulation untersucht. Dabei werden Schubspannungs-Reynoldszahlen bis Reτ = 2880 und Rohrlängen bis L = 42R berücksichtigt. Es wird das Konvergenz- und Skalierungsverhalten verschiedener statistischer Momente der Geschwindigkeitsverteilung untersucht und in Bezug auf VLSMs diskutiert. Die folgende Analyse der axialen Energietransportgleichung des gefilterten Geschwindigkeitsfeldes legt offen, dass VLSMs Energie von der mittleren Strömung zugeführt bekommen, ähnlich den kleinskaligen Strukturen durch den turbulenten Produktionsmechanismus. Die verschiedenen Terme der Energiebilanz werden sowohl anhand von mittleren Profilen, als auch instantanen Strömungsvisualisierungen und drei-dimensionalen Korrelationen diskutiert, wobei auch auf das Phänomen der inversen turbulenten Energiekaskade eingegangen wird. Die Forschungsarbeit gewährt dabei neue Einblicke in die Interaktion der VLSMs mit dem turbulenten Wandzyklus und trägt zum besseren Verständnis der turbulenten Rohrströmung bei. Turbulent pipe flow is not only of importance to engineering applications but also of fundamental interest to the study of wall-bounded turbulence. In the present work, the interaction of the so-called very-large-scale motions (VLSMs) with the near-wall, small-scale turbulence is explored by means of direct numerical simulation for friction Reynolds numbers up to Reτ = 2880 and pipe lengths up to L = 42R. Besides, the convergence and the scaling of different order moments of the velocity distribution are studied and also discussed with regard to VLSMs. The subsequent analysis of the streamwise energy budget equation of the filtered velocity field reveals that VLSMs obtain their energy from the mean velocity field via a production mechanism similar to the one known from the near-wall cycle. Moreover, the different energy budget terms are investigated by means of statistical averages, instantaneous flow field visualisations, and three-dimensional correlations, wherein the backscattering phenomenon is also dealt with. In brief, the research sheds new light on our understanding of the interaction between VLSMs and the near-wall cycle and leads to a better grasp of turbulent pipe flow in general.
Author: Ronald J. Adrian Publisher: Cambridge University Press ISBN: 0521440084 Category : Science Languages : en Pages : 585
Book Description
Particle image velocimetry, or PIV, refers to a class of methods used in experimental fluid mechanics to determine instantaneous fields of the vector velocity by measuring the displacements of numerous fine particles that accurately follow the motion of the fluid. Although the concept of measuring particle displacements is simple in essence, the factors that need to be addressed to design and implement PIV systems that achieve reliable, accurate, and fast measurements and to interpret the results are surprisingly numerous. The aim of this book is to analyze and explain them comprehensively.
Author: Preyank Sheth Publisher: ISBN: Category : Languages : en Pages : 273
Book Description
This study is aimed at better understanding the nature of bend effects in a high Reynolds number duct flow. Bend effects have been previously studied using laser Doppler velocimetry and hot wire anemometry, but these are point measurement techniques, which limits the amount and type of data that can be obtained. The current work employs particle image velocimetry to present detailed field measurements of the flow velocity throughout the bend, including upstream and downstream sections. Additionally, velocity measurements have been carried out at three different Reynolds numbers to establish the dependence or independence of the bend effects on the flowrate. Associated turbulence quantities have also been calculated and presented in an intuitive, graphical manner. The test section is a square cross-sectioned duct, containing a 90 degree bend preceded by an 5Dh[subscript] upstream section and a 10Dh[subscript] downstream straight section, where Dh[subscript] is the hydraulic diameter. Turbulent flow entering the upstream section is fully-developed to allow the isolation of the bend effects. At Re ~ 2.76X105, detailed velocity measurements are acquired at 12 streamwise locations in three streamwise-radial planes at different heights (top, middle and bottom). Complementary data are obtained in a more limited set of locations at Re~1.76X105 and Re~3.20X105 to allow comparison of the bend effects at different flowrates. Turbulence intensities and the Reynolds shear stress components are calculated and presented for all three Reynolds numbers. One of the major aims of this work is to provide a benchmark for computational codes developed to study bend effects in a turbulent pipe flow. To allow easy comparison of these codes to the results of the current study, all the measured and calculated quantities are plotted in a curvilinear coordinate system in addition to the native cartesian (global) coordinate system.
Author: F.T. Nieuwstadt Publisher: Springer Science & Business Media ISBN: 940111689X Category : Technology & Engineering Languages : en Pages : 532
Book Description
The European Turbulence Conferences have been organized under the auspices of the European Mechanics Committee (Euromech) to provide a forum for discussion and exchange of recent and new results in the field of turbulence. The first conference was organized in Lyon in 1986 with 152 participants. The second and third conferences were held in Berlin (1988) and Stockholm (1990) with 165 and 172 participants respectively. The fourth was organized in Delft from 30 June to 3 July 1992 by the J.M. Burgers Centre. There were 214 participants from 22 countries. This steadily growing number of participants demonstrates both the success and need for this type of conference. The main topics of the Fourth European Turbulence Conference were: Dynamical Systems and Transition; Statistical Physics and Turbulence; Experiments and Novel Experimental Techniques; Particles and Bubbles in Turbulence; Simulation Methods; Coherent Structures; Turbulence Modelling and Compressibility Effects. In addition a special session was held on the subject of CeBular Automata. Each of the sessions was introduced with a survey lecture. The lecturers were: W. Eckhaus, AJ. Libchaber, L. Katgerman, F. Durst, M. Lesieur, B. Legras, D.G. Dritschel and P. Bradshaw. The contributions of the participants were subdivided into oral and poster presentations. In addition to the normal program, some Speciai Interest Groups of Ercoftac (European Research Community on Flow, Turbulence and Combustion) presented their research activities in the form of a poster.
Author: Markus Raffel Publisher: Springer Science & Business Media ISBN: 3540723072 Category : Technology & Engineering Languages : en Pages : 460
Book Description
This immensely practical guide to PIV provides a condensed, yet exhaustive guide to most of the information needed for experiments employing the technique. This second edition has updated chapters on the principles and extra information on microscopic, high-speed and three component measurements as well as a description of advanced evaluation techniques. What’s more, the huge increase in the range of possible applications has been taken into account as the chapter describing these applications of the PIV technique has been expanded.
Author: J. Westerweel
Author: J. Westerweel
Author: Zeinab Hallol
Author: Emir Öngüner
Author: Ian Grant
Author: Christian Bauer
Author: Ronald J. Adrian
Author: Preyank Sheth
Author: 
Author: F.T. Nieuwstadt
Author: Markus Raffel