Download or read book Experimental Investigation of Low Mode Number Cylinders Subjected to Vortex induced Vibrations written by Ersegun Denis Gedikli and published by . This book was released on 2014 with total page 260 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Experimental Investigation of Vortex induced Vibration of a Circular Cylinder written by Asif Khalak and published by . This book was released on 1996 with total page 352 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book An Experimental Investigation of Vortex Shedding from Rotating Circular Cylinders written by Jerome Francis Jaminet and published by . This book was released on 1968 with total page 110 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Critical Review of the Intrinsic Nature of Vortex Induced Vibrations written by Turgut Sarpkaya and published by . This book was released on 2003 with total page 126 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is a concise and comprehensive review of the progress made during the past two decades on vortex induced vibration (VIV) of mostly circular cylindrical structures subjected to steady uniform flow. The critical elements of the evolution of the ideas, theoretical insights, experimental methods, and numerical models are traced systematically; the strengths and weaknesses of the current state of the understanding of the complex fluid/structure interaction are discussed in some detail. Finally, some suggestions are made for further research on VIV. The organization of the paper is given at the end of the next section.
Download or read book Flow induced Vibration written by Robert D. Blevins and published by . This book was released on 2001-01-01 with total page 477 pages. Available in PDF, EPUB and Kindle. Book excerpt: Focuses on applications for offshore platforms and piping; and, wind-induced vibration of buildings, bridges, and towers. This title also focuses on acoustic and mechanical vibration of heat exchangers, power lines, and process ducting.
Download or read book Numerical and Experimental Investigation of Vortex excited Oscillations of a Circular Cylinder at Low Reynolds Numbers written by Petros Anagnostopoulos and published by . This book was released on 1985 with total page 768 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Flow Induced Vibrations written by Eduard Naudascher and published by Courier Corporation. This book was released on 2012-03-27 with total page 434 pages. Available in PDF, EPUB and Kindle. Book excerpt: Despite their variety, the vibration phenomena from many different engineering fields can be classified into a relatively few basic excitation mechanisms. The classification enables engineers to identify all possible sources of excitation in a given system and to assess potential dangers. This graduate-level text presents a synthesis of research results and practical experience from disparate fields in the form of engineering guidelines. It is particularly geared toward assessing the possible sources of excitation in a flow system, in identifying the actual danger spots, and in finding appropriate remedial measures or cures. Flow-induced vibrations are presented in terms of their basic elements: body oscillators, fluid oscillators, and sources of excitation. By stressing these basic elements, the authors provide a basis for the transfer of knowledge from one system to another, as well as from one engineering field to another. In this manner, well-known theories on cylinders in cross-flow or well-executed solutions from the field of wind engineering--to name just two examples--may be useful in other systems or fields on which information is scarce. The unified approach is broad enough to permit treatment of the major excitation mechanism, yet simple enough to be of practical use.
Download or read book Hydrodynamics Around Cylindrical Structures written by Jorgen Fredsoe and published by World Scientific. This book was released on 1997-03-17 with total page 550 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book discusses the subject of wave/current flow around a cylinder, the forces induced on the cylinder by the flow, and the vibration pattern of slender structures in a marine environment.The primary aim of the book is to describe the flow pattern and the resulting load which develops when waves or current meet a cylinder. Attention is paid to the special case of a circular cylinder. The development in the forces is related to the various flow patterns and is discussed in detail. Regular as well as irregular waves are considered, and special cases like wall proximities (pipelines) are also investigated.The book is intended for MSc students with some experience in basic fluid mechanics and for PhD students.
Download or read book Experimental and Numerical Analysis of a Pivoted Cylinder Subjected to Vortex induced Vibrations written by Daniel Alejandro Mella Vivanco and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Interfering of Two Tandem Cylinders Undergoing VIV written by Milad Armin and published by . This book was released on 2016 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Behaviour of two cylinders in tandem subjected to a stream of steady uniform flow is investigated. This research includes experimental and mathematical simulation so that a better understanding of the interaction between two bodies undergoing vortex induced vibration (VIV) can be achieved while one is submerged in the wake of the other. Amplitude and frequency of oscillation are observed for both cylinders when they are placed at different distances from each other. Positioning cylinders at various spacings can help to shed some light on the interaction mechanism of the upstream wake and trailing cylinder. An experimental investigation was carried out in sub-critical Reynolds number and low mass-damping to simulate the conditions in which offshore structures are deployed. Initially, two identical cylinders are placed in-line with the stream at various spacings. The response of leading cylinder is observed to be similar to that of an isolated cylinder experiencing VIV at all spacings. On the other hand, trailing cylinder response is observed to increase with flow velocity at small and medium spacings. Moreover,as the spacing grows large downstream response becomes more similar to that of the leading cylinder. Motion trajectory of trailing cylinder is significantly influenced by the leading body, and does not follow the typical figure of eight observed for an isolated cylinder at all velocities. Frequency power spectrum of obtained time histories reveals that two sources of excitation exist for trailing cylinder. Corresponding motion to each excitation source is determined using Fast Fourier Transform.The second set of experiment was conducted using similar cylinders with different natural frequencies to observe how it influences the interaction between two cylinders. It was observed that behaviour of trailing cylinder alters in comparison with initial set up. However, two sources of excitation are still detected in this set-up. Mathematical simulation is pursued by modelling the oscillating cylinders with a simple mass-spring-damper system. Furthermore, the force exerted to cylinders by wake is simulated by wake oscillators which can capture the self-exciting and self-limiting nature of VIV phenomenon. Two equations are coupled together by assuming that wake force is proportional to cylinder acceleration. Then, the system of equations is solved analytically,and results are compared to those obtained by a SimuLink model of the system. SimuLink model is solved by numerical RungeKutta method. It was observed that model is successful in simulating leading cylinder vibration amplitude,while it, initially, fails drastically to predict the oscillation amplitude of trailing cylinder due to buffeting vortices. Two terms were added to accommodate the effect of upstream wake on the trailing cylinder, to modify the force in the equation of motion which is respectively proportional to acceleration and velocity of the cylinder. Moreover, acceleration term is determined by fitting a linear function of the variable to the difference between upstream and downstream wake force obtaining from the experimental investigation results. Additionally, the damping term is determined by optimization of variance between simulation and experiment results. Such an observation can confirm that upstream turbulent wake has a significant influence on added mass coeffcient of the trailing cylinder which both are observed to be dependent on upstream Strouhal number.Overall, the agreement between mathematical model and experimental results is evaluated for both cylinders. Model error for trailing cylinder is calculated between 20% to 30% in cross-flow direction. This error is lower than that of the leading cylinder which is a well established method in literature for simulating VIV of an isolated cylinder.
Download or read book Experimental Investigation of a Cylinder in Axial Motion at Low Reynolds Number microform written by Ui, Tsukasa Jeff and published by Ann Arbor, Mich. : University Microfilms International. This book was released on 1984 with total page 288 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract.
Download or read book Vortex induced Vibration and Forced Oscillation Motion of a Circular Cylinder Fitted with a Single Spanwise Tripwire written by Ehsan Vaziri and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This experimental study consisted of two main parts. The first part investigated the control induced by a spanwise tripwire on a circular cylinder undergoing one-degree-of-freedom vortex-induced vibration (VIV). The cylinder vibrates in the cross-stream direction as a result of the fluid forcing in a recirculating water tunnel. Changing mass and damping ratios in the test rig allowed the investigation at different VIV response branches. The tripwire diameter was 6.25% of the cylinder diameter. Experimental research was conducted by attaching the large-scale tripwire along the span of the cylinder at various angular positions ranging from 0° to 180° (with respect to the most upstream point of the cylinder). Along with measuring the trajectory of the cylinder motion, the instantaneous velocity field in the near wake of the cylinder was obtained simultaneously at a fixed Reynolds number of 10,000 (based on the cylinder diameter) using a Particle Image Velocimetry (PIV) system. Various vortex-formation modes induced by the tripwire were observed. It was shown that the oscillation pattern, frequency, and amplitude of the cylinder can be altered significantly depending on the angular position of the tripwire and the VIV response branch. For specific tripwire positions, increases of up to 52 times and decreases of up to 98% were identified in the oscillation amplitude of the tripped cylinder compared to the amplitude of the clean cylinder.The second part of the study investigated the effects of the tripwire on the flow structure behind a circular cylinder forced to oscillate harmonically at prescribed amplitudes and frequencies in the cross-stream direction. Oscillation amplitudes are 0.05, 0.3 and 0.6 times the cylinder diameter, and oscillation frequencies are 0.61, 0.8, and 1 times the vortex shedding frequency of the stationary clean cylinder counterpart. For a fixed oscillation amplitude and frequency, the tripwire can either induce intermittent switching between various vortex shedding modes or cause a wake mode to be dominant during the entire observed oscillation motion by altering the vortex shedding mechanism. The wake of the tripped cylinder undergoing the lowest amplitude forced oscillation motion showed resemblance to the wake of the stationary tripped cylinder.
Download or read book Applied mechanics reviews written by and published by . This book was released on 1948 with total page 400 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Flow Control Techniques and Applications written by Jinjun Wang and published by Cambridge University Press. This book was released on 2018-12-13 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 Flow induced Vibration of Circular and Square Cylinder with Low Mass and Damping written by Jisheng Zhao and published by . This book was released on 2012 with total page 362 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis investigates cross-flow flow-induced vibration of elastically mounted rigid circular and square cylinders with low mass and damping ratio over a range of low and vibration parameters. In particular, two typical body oscillator phenomena of flow-induced vibration, vortex-induced vibration and galloping, are studied experimentally. Thus, the study consists of two main parts. The first part, using simultaneous displacement, force and vorticity measurements, investigates the dynamic response of a circular cylinder undergoing transverse free vortex-induced vibrations and controlled trajectory-following vibrations. The second part characterises the amplitude and frequency responses of a square cylinder with angle of attack variation. Despite extensive work has been undertaken to understand the fundamental characteristics of free and forced vibrations of a circular cylinder, there are still a number of unresolved questions in the literature concerning the similarities and differences between the free and forced vibration cases. In order to directly compare these two vibration cases, a low-friction air-bearing rig and a real-time feedback control system were therefore designed and implemented in experiments. The major results obtained show that the transverse lift force and the decomposed vortex force experienced by a cylinder forced to follow the trajectory of free VIV are identical to the free vibration case, when both the total phase and the vortex phase relative to the body motion are constantly stable. However, significant differences between the two vibration cases are found at a reduced velocity located in the middle upper branch of VIV where largest-scale body vibration occur with complex switching phenomena in the total phase and the vortex phase. The results from the second part, flow-induced vibration of a square cylinder with angle of attack variation, show that the cylinder, as expected, experiences galloping at the zero angle of attack orientation (0 degree) and vortex-induced vibration at the diamond orientation (45 degree). As the angle of attack is varied from 45 degree to 0 degree, the body can undergo combinations of both vortex-induced vibration and galloping in a mixed response region. In this region, the oscillation amplitude response exhibits a new branch that exceeds the responses resulting from the two body-oscillator phenomena independently. For velocities above this resonant region, the body oscillation frequency splits into two diverging branches. Further, analysis of the amplitude reveals that the transition between galloping and vortex-induced vibrations occurs over a narrow range of angle of incidence. Despite the rich set of states found in the parameter space the vortex shedding modes remain very similar to those found previously in vortex-induced vibration.
Download or read book Two dimensional Numerical Study with LES Modeling of Vortex Induced Vibration of a Circular Cylinder Subjected to a Uniform Flow at a Moderate Reynolds Number written by Helmi Nazmi Al-Jamal and published by . This book was released on 2002 with total page 154 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Investigating Phenomena in Vortex induced Vibration of a Cylinder Using Controlled Vibration written by Timothy Lester Morse and published by . This book was released on 2009 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this study, we use controlled vibration, where we oscillate a rigid cylinder with a prescribed motion, in a fluid flow, in order to provide insight into aspects of vortex-induced vibration. We make extensive measurements of the fluid forces on a cylinder that oscillates sinusoidally, transverse to a free stream, at both Re = 4,000 and Re = 12,000, and generate high resolution contour plots of various fluid forcing quantities in the plane of normalized amplitude and wavelength. With such resolution, we are able to discover discontinuities in the force and phase contours, which enable us to clearly identify boundaries separating different fluid forcing regimes. These boundaries appear remarkably similar to boundaries separating different vortex formation modes in the Williamson & Roshko (1988) map of regimes. Wake vorticity measurements (using DPIV) exhibit the 2S, 2P, and P+S modes, as well as a regime where the vortex formation is not synchronized with the cylinder oscillation. A further new discovery is the existence of a region where two vortex formation regimes overlap. Associated with this overlap region, we identify a distinct mode of vortex formation where two pairs of vortices are shed per cycle of oscillation (similar to the 2P mode) but the secondary vortex is much weaker, which we have termed '2POVERLAP ', or simply the '2PO ' mode. This '2PO ' mode is of particular importance, as it is responsible for generating the peak resonant response of the body. By examining the energy transfer from fluid to body motion we predict the response of an elastically mounted cylinder that agrees remarkably well with measured free vibration responses. We introduce the concept of an "energy portrait", which allows us to identify stable and unstable amplitude response solutions and thus to predict clearly the hysteretic and intermittent switching mode transitions, both of which correspond with such phenomena measured from free vibration. In addition to predicting steady state (sinusoidal) behavior, we develop a quasi-steady model which allows us to predict the dynamics of a freely oscillating cylinder having transient or unsteady behavior. Using this model, we find a regime of normalized flow velocity where steady state vortex-induced vibrations cannot occur, and the cylinder can only oscillate with unsteady motion. Further studies include the effect of Reynolds number on the critical mass for an oscillating body, below which a structure will vibrate up to infinite normalized velocity. Finally, we measure the effect of spanwise end conditions on a free vibration response.
