Dissertations / Theses on the topic 'Flow; cylinders; induced vibration'
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Thekkoodan, Dilip Joy. "Interaction of cylinders In proximity under flow-induced vibration." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/92126.
Full textCataloged from PDF version of thesis.
Includes bibliographical references (pages 57-59).
This study examines the influence of a stationary cylinder that is placed in proximity to a flexibly mounted cylinder in the side-by-side arrangement. The problem is investigated with an immersed-boundary formulation of a spectral/hp element based (Nektar-SPM) fluid solver. The numerical method and its implementation is validated with benchmark test cases of the flow past an isolated cylinder in both the stationary and flexibly mounted configurations. The study examines a parametric space spanning 6 center-to-center spacing configurations in the range 1.5D-4D and 13 equispaced reduced velocities in the range 3.0-9.0. The simulations are performed in two-dimensional space and the Reynolds number is held at 100. The response characteristics of the moving cylinder are classified into regimes based on the shape of the response curve and the variation of the r.m.s. lift coefficient. It is shown that the moving cylinder influences the lift and drag force characteristics on the stationary cylinder and the frequency composition in the wake. A detailed look at the frequencies and the relative strengths of the frequencies indicates a diminishing influence of the moving cylinder on the stationary cylinder, both with increasing separation and smaller amplitudes. By examining the wake patterns and monitoring the frequencies in the wake of each cylinder, the interference level is qualified and explained to be the basis of the different families of response.
by Dilip Joy Thekkoodan.
S.M.
Elbanhawy, Amr Yehia Hussein. "On numerical investigations of flow-induced vibration and heat transfer for flow around cylinders." Thesis, University of Manchester, 2011. https://www.research.manchester.ac.uk/portal/en/theses/on-numerical-investigations-of-flowinduced-vibration-and-heat-transfer-for-flow-around-cylinders(6722ba6d-80de-47f4-a14d-191d4e9ed7fb).html.
Full textRao, Zhibiao. "The flow of power in the vortex-induced vibration of flexible cylinders." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/100141.
Full textCataloged from PDF version of thesis.
Includes bibliographical references (pages 255-259).
In this thesis techniques are developed which permit the identification of power-in and power-out regions of long cylinders exposed to flow-induced vibration. The data used to illustrate the techniques come from a set of vortex-induced vibration model tests conducted by Shell Oil Co in 2011 at the Marintek facility in Trondheim, Norway. The identification of power-in regions allows one to address the practical problem of determining the primary source of vibration energy when the long cylinder has components of various shapes, such as when buoyancy modules are used in staggered configurations. The identification of power-out regions has a direct practical connection to the estimation of damping magnitude and location on cylinders with varying cross-sections in non-uniform flows. The vibration intensity technique is used in this thesis to locate the power-in and power-out regions of a long flexible cylinder in a steady flow. This method also allows the exploration of the occurrence of secondary power-in regions after suppressing the primary power-in zones. Results may provide useful guidance for the installation and repair of suppression devices such as helical strakes. Three methods are presented to address a practical problem: "When buoyancy modules are applied in a staggered pattern on an otherwise bare cylinder, which distribution patterns result in VIV response dominated by buoyant or bare regions?" Based on the data analysis of five staggered buoyancy pipes, the three methods yielded the same results in identifying the winner. A dimensionless parameter, the "predictor", is proposed. The predictor relies only on the diameters and lengths of bare and buoyant segment. The predictor is verified with an independent set of VIV tests. An equivalent damping parameter is proposed for the purpose of classifying all flexible cylinder VIV response cases onto a single plot of response versus the equivalent damping parameter. After taking Reynolds number into account, results show that the amplitude for pipes with and without helical strakes at different Reynolds numbers can be collapsed onto a single curve as a function of the newly defined equivalent damping parameter.
by Zhibiao Rao.
Ph. D.
Yang, Wenchao. "Two-dimensional Wakes and Fluid-structure Interaction of Circular Cylinders in Cross-flow." Diss., Virginia Tech, 2018. http://hdl.handle.net/10919/97563.
Full textPHD
Chung, Tae-Young. "Vortex-induced vibration of flexible cylinders in sheared flows." Thesis, Massachusetts Institute of Technology, 1987. http://hdl.handle.net/1721.1/14729.
Full textHumphries, J. A. "Vortex induced vibrations of slender cylinders in sheared flow." Thesis, Cranfield University, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.383657.
Full textOrtega, Mariana Silva. "Suppression of vortex-induced vibration of a circular cylinder with fixed and rotating control cylinders." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/3/3135/tde-15072016-152949/.
Full textA indústria offshore está envolvida no desenvolvimento de novas plataformas flutuantes como Spar, semi-submersível, TLP, FPSO e monocoluna para a exploração de águas profundas e ultra-profundas. Alguns destes sistemas flutuantes têm seções transversais circulares (ou de outras seções rombudas) sendo susceptíveis à vibrações induzidas por vórtices (VIV). A esteira de vórtices desprendida de um corpo rombudo pode ser alterada ou suprimida ao longo de uma faixa de número de Reynolds. Várias técnicas de controle do escoamento foram sugeridas e testadas em geometrias simples, resultando na redução de forças de sustentação e arrasto. Um desses métodos é o controle de camada limite por superfícies móveis (CCLSM), no qual cilindrinhos rotativos de controle são colocados próximos ao corpo rombudo. Neste trabalho, este método foi abordado através de uma investigação experimental como um supressor de VIV para o escoamento omnidirecional. Neste escopo três diferentes configurações foram montadas para comparar o efeito de supressão sobre um cilindro liso rodeado por dois, quatro e oito cilindros de controle, distribuídos simetricamente em torno dele. Foram realizados ensaios com o modelo estático, ensaios de VIV em um grau de liberdade com cilindros de controle fixos e rotativos. Foram medidos deslocamento e forças de sustentação e arrasto. Os resultados mostraram que a posição dos cilindros de controle é um parâmetro importante para a supressão de VIV. A configuração com dois cilindros de controle aumentou as forças de sustentação e arrasto. Diferentemente, as configurações de quatro e oito cilindros de controle mostraram-se mais eficazes para suprimir VIV. Além disso, todos os casos da configuração de oito cilindros de controle fixos apresentaram redução nas amplitudes de vibração e nas forças de sustentação e arrasto, quando comparados com um cilindro liso. No entanto, quando os cilindros de controle foram acionados para rotacionar, mostrou-se um aumento na força de arrasto em relação aos cilindros de controle fixos.
杜平 and Ping To. "Interference effects on the flow-induced vibration of a flexible circular cylinder due to a larger-sized cylinder in the vicinity." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1998. http://hub.hku.hk/bib/B31237769.
Full textTo, Ping. "Interference effects on the flow-induced vibration of a flexible circular cylinder due to a larger-sized cylinder in the vicinity /." Hong Kong : University of Hong Kong, 1998. http://sunzi.lib.hku.hk/hkuto/record.jsp?B19712121.
Full textResvanis, Themistocles L. "Vortex-induced vibration of flexible cylinders in time-varying flows." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/93782.
Full textThis electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 221-226).
This thesis investigates two aspects of Vortex-Induced Vibrations (VIV) on long flexible cylinders. The work is split into a minor and major part. The minor part addresses the effect of Reynolds number on flexible cylinder VIV. The major contribution addresses the prediction of VIV under unsteady current excitation or time-varying flows. The study on the effect of Reynolds number makes extensive use of a recent set of experiments performed by MARINTEK on behalf of SHELL Exploration and Production Co. Three 38[gamma] long cylinders of different diameters were towed through the ocean basin over a wide range of Reynolds numbers in both uniform and sheared flows. The experimental data showed that the response amplitudes and dimensionless response frequency are strongly influenced by the Reynolds number. Both of these Reynolds effects should be of interest to riser designers that traditionally rely on experimental data obtained at much lower Reynolds numbers. In this thesis, I propose a dimensionless parameter, [gamma], that governs whether lock-in under unsteady flow conditions is possible and show that it is useful for determining a priori whether the response under unsteady conditions will be similar to the response under steady flows. The unsteady flow parameter, [gamma], describes the change in flow speed per cycle of cylinder vibration and is defined as: ... The experimental data necessary to support this work is taken from a set of experiments performed at the State Key Laboratory of Ocean Engineering at Shanghai Jiao Tong University (SJTU), where a 4[gamma] long flexible cylinder was towed through an ocean basin under carefully selected amounts of acceleration/deceleration. Analysis of the experimental data showed that the response can typically be divided into three regimes based on the [gamma] value: For very quickly accelerating flows ([gamma] > 0.1) the cylinder cannot react quickly enough and at most a couple of cycles of small amplitude vibration will be observed. For moderately accelerating flows (0.02 < [gamma] < 0.1), the cylinder will typically start vibrating and can build up a significant response. However, most of the time, the flow will have exited the required synchronization region before the cylinder manages to reach the large amplitudes observed in steady flows. For very slowly accelerating flows ([gamma] < 0.02), the flow is changing considerably slower than the cylinder's reaction time and thus, the cylinder has more than enough time to build up its response. Under these conditions, the observed response is qualitatively similar to the response of flexible cylinders in steady flows. The [gamma] dependence that was identified in the SJTU data is not limited to that specific situation but instead, is a general property of low mass ratio cylinders vibrating in unsteady flows. This is shown by demonstrating how the unsteady flow parameter, [gamma], can be used to analyze unsteady response data from the aforementioned SHELL tests where the riser models were considerably longer than the SJTU model. This thesis shows how a single ramp test -- where the towing speed is continuously varied in a control manner -- may be used to obtain the same information as 10 constant speed tests covering the range of speeds. This can and will significantly reduce the number of runs necessary to completely characterize the VIV response of flexible cylinders and will translate into large cost savings in the future. The thesis closes by describing the differences observed in the VIV response at high mode numbers depending on whether the time-varying flow was accelerating or decelerating. In both situations a 'hysteresis' effect is noted, where the cylinder is found to 'lag behind' preferring to vibrate in the previously excited mode as a result of cylinder lock-in. In accelerating flows, this means that the cylinder will typically be responding one mode lower than it would have in a steady flow. In decelerating flows, the same 'lag' or 'hysteresis' will cause the cylinder to respond one (or more) mode number(s) higher than it would have in a steady flow.
by Themistocles L. Resvanis.
Ph. D.
Hobbs, William Bradford. "Piezoelectric energy harvesting: vortex induced vibrations in plants, soap films, and arrays of cylinders." Thesis, Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/33811.
Full textCarmo, Bruno Souza. "On wake interference in the flow around two circular cylinders : direct stability analysis and flow-induced vibrations." Thesis, Imperial College London, 2009. http://hdl.handle.net/10044/1/4697.
Full textZahn, Michael L. "Flow-induced vibration of a single flexible cylinder in a normal triangular array." Thesis, McGill University, 1989. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=55656.
Full textDahl, Jason (Jason Michael). "Vortex-induced vibration of a circular cylinder with combined in-line and cross-flow motion." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/44747.
Full textIncludes bibliographical references (p. 249-256).
Deep water, string-like, marine risers subject to strong ocean currents, suffer from vortex-induced vibrations (VIV), where vortex shedding interacts with the structural properties of the riser, resulting in large amplitude vibrations in both in-line and cross-flow directions. This thesis presents an experimental approach to model and quantify the motions and hydrodynamic forces associated with the excitation of a deep water marine riser by considering the combined cross-flow and in-line excitation of a rigid cylinder. For deep water risers, the excitation of the structure through vortex shedding can lead to a condition of dual resonance, where the vortex shedding frequency locks in to the effective natural frequency (adjusted for added mass effects) in both in-line and cross-flow directions. Large motion amplitudes are observed in this condition along with large magnitude third harmonic forces in lift. Flow visualization of the wake behind the cylinder in combined in-line and cross-flow motion, shows that third harmonic forces are caused by the relative motion of the cylinder with respect to a '2P' (two pairs of vortices) or '2T' (two triplets of vortices) shedding pattern, since vortices shed in these modes remain in close proximity to the cylinder over one cycle of motion. Forced motions of a cylinder with combined in-line and cross-flow motions are performed, generating a database of force coefficients to be used in riser VIV prediction. The assumption of dual resonance is used to predict the motions of an elastically mounted rigid cylinder using measurements from forced cylinder motions. Two passive vortex suppression methods are studied for eliminating combined cross-flow and in-line cylinder motions and suppressing large third harmonic forces.
by Jason Dahl.
Ph.D.
Luk, K. F. "Experiment on flow-induced vibration of an airfoil due to vortex shedding generated from upstream circular cylinder /." View Abstract or Full-Text, 2002. http://library.ust.hk/cgi/db/thesis.pl?MECH%202002%20LUK.
Full textIncludes bibliographical references (leaves 54-57). Also available in electronic version. Access restricted to campus users.
Cicolin, Murilo Marangon. "Supressão da vibração induzida por vórtices de cilindros com malha permeável." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/3/3135/tde-07032016-102934/.
Full textThe phenomenon of vortex-induced vibration (VIV) is particularly harmful to submarine structures such as risers used for oil extraction. The most usual way to attenuate the effects of VIV is the installation of suppressors, like strakes or fairings. Among them, All Brow Universal Components developed a VIV suppressor called Ventilated Trousers (VT), which consist of a permeable mesh made of a flexible net and tens of bobbins. Three different models of suppressors based on permeable meshes have been assembled with the objective to understand the hydrodynamic mechanism behind the suppression: one model identical to the VT and two meshes with different bobbin geometries and distribution. Tests were carried out with xed models and models free to oscillate in one degree of freedom varying the structural damping. Displacements, drag and lift forces were measured. Results showed that the VT suppressor reduced vibration amplitudes, lift and drag forces when compared to an oscillating circular cylinder. However, it increased drag force when compared to a fixed circular cylinder. The mesh geometry proved to be important to VIV suppression. Models that had an external disc on the bobbins avoided the appearance of a gap between the model and the cylinder. Three hypotheses were formulated to explain how the VT suppressor works. The first one says that the increase on hydrodynamic damping is responsible for suppression. In fact, tests showed that the VT increased hydrodynamic damping and, consequently, reduced the VIV response. However, this effect alone does not explain the suppression as a whole. The other two hypotheses related to two-dimensional and three-dimensional wake changes were evaluated, but it cannot be stated that any of them, on its own, is responsible for the whole of the suppression mechanism.
Franzini, Guilherme Rosa. "Investigação experimental do escoamento ao redor de cilindros inclinados, sujeitos a condições de contorno assimétricas nas extremidades." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/3/3135/tde-26072013-165702/.
Full textThe flow around yawed cylinders, or oblique flow, is a common subject in several engineering applications. Despite the flow around a non-yawed cylinder consists on a classical and extensively investigated problem, there is a considerable lower number of investigation concerning the oblique flow. The most employed approach aiming at investigating the oblique flow is the so called Independence Principle, which states that the flow characteristics depend only on the component of the free-stream that is normal to the cylinder axis. Three groups of experiments were carried out aiming at a better understanding of the flow around yawed cylinders. Five yaw angles defined between the cylinder axis and the direction orthogonal to the free-steam were tested, namely: theta = 0°, 10°, 20°, 30° e 45°. From the first group of experiments, the results obtained with stationary cylinders yawed in the upstream orientation shown that the mean drag coeficient matches the classical results from the non-yawed cylinder, if the component of the free-stream that is orthogonal to the cylinder axis is employed in the normalization of the hydrodynamic force. Concerning vortex-induced vibrations experiments with one and two degrees-of-freedom, a decrease was observed in the maximum oscillation amplitude. For all the experiments, it was observed that the results obtained from the upstream orientation tests can be different from those obtained for the downstream orientation ones. The larger the yaw angle, the larger are the differences, which are associated to the asymmetric end conditions.
Junior, Leonidio Buk. "Estudo numérico do escoamento ao redor de um cilindro fixo." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/3/3150/tde-12072007-160644/.
Full textIn this work, the incompressible flow around a stationary cylinder is investigated by using the Finite Element Method. Two-dimensional simulations in time domain have been carried out, with Reynolds number varying from 100 to 600, using non-structured meshes with triangular elements. The aim of this work is to analyze the efficiency of Penalty Methods, which is the way that the velocity-pressure coupling problem is treated here, in Navier-Stokes equations solution. The solution convergence from different values of penalty parameter is evaluated and it is suggested a method to estimate it. In addition, it is studied the sensibilty of response when using the mass matrix in consistent or lumped format. At last, a comparison between average drag coefficient, fluctuating lift and Strouhal number obtained here and those found in other publications is shown.
Assi, Gustavo Roque da Silva. "Estudo experimental do efeito de interferência no escoamento ao redor de cilindros alinhados." Universidade de São Paulo, 2005. http://www.teses.usp.br/teses/disponiveis/3/3150/tde-11012006-154457/.
Full textThis MSc Thesis presents an experimental study on flow-induced vibrations and interference effects around rigid circular cylinders free to oscillate transversally to the flow. Firstly, it justifies the real needs of an experimental approach within the context of offshore engineering, which motivates this project. After that, presents a review over bluff-bodies flows followed by some consideration concerning flow-induced vibrations. Special attention is found over the oscillations caused by VIV Vortex-Induced Vibrations and galloping phenomena, which are attributed to excite either a single isolated cylinder or a pair of tandem interfering cylinders. The experimental methodology is shown, describing the applications of elastic bases with one degree of freedom. Experimental techniques and signal analysis procedures are discussed considering the executions of these experiments in two water channel facilities. Presented, discussed and compared results involve: dynamic responses in amplitude and dominant oscillation frequency; instantaneous phase angle between fluid forces and cylinder displacement and phase angle betweens the two cylinders oscillations; and wake dynamics measurements and visualizations employing PIV technique. Cylinders are arranged as follow: single isolated cylinder; tandem pair with upstream one free to oscillate; tandem pair with downstream one free to oscillate; tandem pair with both cylinders free to oscillate. All carefully analyzed arrangements present low-mass parameter and very low damping . Gaps between cylinder centers vary through . Reduced velocity range is comprised in. The isolated cylinder case presented a typical VIV response, with three identified branches (initial, upper and lower). The instantaneous phase angle intermittency phenomenon was observed in transition regions. The 2S and 2P vortex modes were verified by PIV technique. These data showed to be in accordance to other literature measurements and are employed as reference results for comparisons throughout this text. The dynamic response of a cylinder oscillating upstream a fixed one showed a typical VIV behavior. From this can be concluded that the downstream cylinder does not imply any interference phenomenon for analyzed gaps and velocities. On the other hand, major interference effects occur when a downstream cylinder is oscillating in the wake of another fixed one. This configuration, which is the focus of this study, does not show a typical VIV response, since amplitude curves present a crescent branch after the typical synchronization regime. It does not either present a typical galloping excitation response, since the fluid forces are not in phase with the cylinder velocity. Thus, a new suggested name, WIV Wake-Interference Vibrations, describes the phenomenon responsible for these excitations, which combines: lock-in of shedding frequency from VIV; and asymptotically crescent response from galloping-like excitations. When both cylinders are free to oscillate, the upstream one presents the typical VIV response, while the downstream one passes through three branches with discontinuities, excited by WIV. Finally, it can be concluded that is not convenient to call galloping excitation these crescent branches for interference arrangements. It can be understood that the dynamic response is being excited by the interference effects from upstream wake and downstream cylinder vortices. The nomenclature Wake-Interference Vibrations is suggested to be more adequate to the nature of this phenomenon. In addition, PIV visualizations showed to be very important to certify that the formation length decreases while increasing Reynolds number, requiring interference experiments with constant Reynolds numbers. To conclude, some suggestions for future work in this research field are presented.
Gsell, Simon. "Vortex-induced vibrations of a rigid circular cylinder." Phd thesis, Toulouse, INPT, 2016. http://oatao.univ-toulouse.fr/17430/1/gsell.pdf.
Full textHayder, Mir Mohammad Abu 1976. "Cross-flow past oscillating circular cylinders." Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=115685.
Full textExperimental results showed that, for a reasonably large angle of incidence, the flow in the wake of a stationary cylinder pair could be characterized by two distinct periodicities, each of which was dominant on one side of the wake. Furthermore, for lower Reynolds numbers (Re < 1.0x10 4), there was an integral relationship between the two Strouhal numbers, but this integral relationship was no longer maintained for Re > 1.0x10 4. On the other hand, the flow around stationary cylinders for a small angle of incidence was characterized by a single Strouhal number, which remained approximately constant over the entire Reynolds number range.
For all the cylinder configurations investigated the wake flow patterns remained essentially the same as those of the corresponding static cases, when either of the two cylinders was forced to oscillate with a nondimensional forcing frequency less than approximately 0.10. However, beyond this value, the wake underwent considerable modification vis-a-vis when the cylinders were stationary, and the flow pattern within the wake was strongly dependent on the value of the forcing frequency. In particular, there were distinct regions of synchronization between the dominant wake periodicities and the cylinder oscillation; these synchronization regions involved sub- and superharmonics as well as fundamental synchronizations. With either upstream or downstream cylinder oscillation, the wake on the mean-flow side of the downstream cylinder synchronized with the shear layers separated from its outer surface, whereas synchronizations on the mean-flow side of the upstream cylinder were caused by the periodicities formed from the interaction of the other three shear layers.
The flow phenomena associated with the synchronizations were described in detail via flow visualization. The organization of the wake was strongly dependent on whether it was the upstream or downstream cylinder which was oscillating. The synchronized wake on the mean-flow side of the downstream cylinder at both lower and higher oscillation frequencies for upstream cylinder oscillation was observed to form either by the shedding of independent vortices or by the coalescence of two or more vortices. However, for downstream cylinder oscillation, although the synchronizations on this side of the wake at lower oscillation frequencies were caused by the shedding of independent vortices or by the coalescence of vortices, those at higher oscillation frequencies were the consequence of the coalescence of vortices only. For large incidence angles, the number of shear layers separated from the downstream cylinder which interacted with those separated from the upstream cylinder was critical in causing the synchronizations on the mean-flow side of the upstream cylinder.
In most cases, the flow for all the cylinder configurations traversed between the same patterns as those obtained when the cylinders were placed stationary at their minimum and maximum transverse spacings; but there were also some situations where the oscillation of either cylinder pushed the flow outside the regimes associated with the stationary configurations. The synchronization ranges obtained when the upstream or downstream cylinder was oscillating were different from each other, and these ranges were much wider than the corresponding synchronization ranges for a single oscillating cylinder. For two cylinders, an analysis of the fundamental synchronization showed that the frequency range over which this occurred was much broader for upstream cylinder oscillation than for downstream cylinder oscillation. Also, the fundamental synchronization ranges for downstream cylinder oscillation were closer to those for single cylinder oscillation in comparison to those for upstream cylinder oscillation.
Korkischko, Ivan. "Investigação experimental e analítica do escoamento ao redor de cilindro circular com supressores de VIV." Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/3/3150/tde-08122011-150201/.
Full textThe fluid flow around bluff bodies is one of the main problems in fluid mechanics. The investigations of this phenomenon are based on analytical, numerical and experimental techniques. Each technique presents advantages and disadvantages, being impossible the comprehensive characterization of the flow though only one technique for the majority of body geometries and flow conditions. Within this context, the present thesis is proposed, which comprehends a fundamental study about the vortex shedding dynamics based on experimental techniques. Firstly, a hydrodynamic stability study of the flow around a circular cylinder is performed using the Ginzburg-Landau model. The experimental results of this study allowed the validation of numerical simulations and the main experimental technique employed was the Particle Image Velocimetry (PIV). The Fourier series decomposition of velocity fields permits to verify the hierarch suggested by the asymptotic solution of the Hopf bifurcation. Additionally, the results also indicate when the three-dimensionalities become important in the flow. The flow three-dimensionality is closely associated to the vortex-induced vibration (VIV) phenomenon, which exerts damaging effects on a great quantity of structures subjected to fluid flows. In order to suppress VIV, it was realized a parametric investigation of the helical strakes, that are commonly employed in the offshore industry. One verifies that the strakes modify the three-dimensional characteristics of the cylinder wake. Despite of the strake efficiency regarding the VIV suppression, the strakes have some limitations that are inherent to the flow hydrodynamic features. Consequently, it is presented a technique that reduces the three-dimensionalities in order to create a two-dimensional flow, with the possibility of closed-loop active control. The moving surface boundary-layer control (MSBC) suppresses VIV and reduces the drag delaying the cylinder boundary-layer separation through the injection of angular momentum by the rotational control cylinders.
Slisik, Jeffrey A. "FLOW-INDUCED VIBRATION OF CARBON NANOTUBES." University of Akron / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=akron1145032790.
Full textMarcollo, Hayden 1972. "Multimodal vortex-induced vibration." Monash University, Dept. of Mechanical Engineering, 2002. http://arrow.monash.edu.au/hdl/1959.1/7674.
Full textBranković, Maša. "Vortex-induced vibration attenuation of circular cylinders with low mass and damping." Online version, 2004. http://ethos.bl.uk/OrderDetails.do?did=1&uin=uk.bl.ethos.409354.
Full textBrankovič, Maša. "Vortex-induced vibration attenuation of circular cylinders with low mass and damping." Thesis, Imperial College London, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.409354.
Full textJaiswal, Vivek Ph D. Massachusetts Institute of Technology. "Effect of traveling waves on Vortex-Induced Vibration of long flexible cylinders." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/49763.
Full textIncludes bibliographical references (p. 155-160).
Offshore marine risers and pipelines, exposed to ocean currents, are susceptible to Vortex-Induced Vibration (VIV). Accurate prediction of VIV is necessary for estimating the fatigue life as well as for taking corrective measures to prevent the vibrations. State of the art response prediction methods work reasonably well for short flexible cylinders vibrating at frequencies corresponding to low mode numbers (below the tenth mode). However, for long structures, which respond above the tenth mode, lack of experimental data has until recently impeded progress. Results will be presented from recent field experiments conducted in the Gulf Stream and Lake Seneca, NY. These experiments have provided an opportunity for new insights about the VIV of long flexible cylinders, responding at high mode numbers. The experimental results also include insights on the use of VIV suppression devices such as helical strakes. The experiments reveal that the dominant response of long flexible cylinders is often in the form of traveling waves. High spatial density fiber optic strain gauge measurements are used to obtain estimates of the phase speed of the waves, the response amplitude and the added mass coefficient. The mean added mass coefficient for the bare cylinder is shown to be approximately one and the maximum response amplitude is found to be approximately one diameter. A Green's function, response prediction method, is introduced which is able to emulate both the standing and traveling wave properties observed in the experimental data.
(cont.) A novel approach to modeling the excitation force as a combination of standing and traveling wave components is shown to predict the measured response very well. The method is also able to account for high localized damping that result from the use of response suppression devices, such as helical strakes. Many marine risers are composed of nested concentric steel pipes. The relative motion of these concentric pipes in the presence of confined liquids introduces unusual dynamic properties, including the potential for beneficial effects as dynamic absorbers. Numerical and theoretical models are developed as a preliminary step in the design of dynamic absorbers for deep water risers.
by Vivek Jaiswal.
Ph.D.
徐善強 and Sin-keung Chui. "Stability and bifurcation in flow induced vibration." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1997. http://hub.hku.hk/bib/B31235724.
Full textChui, Sin-keung. "Stability and bifurcation in flow induced vibration /." Hong Kong : University of Hong Kong, 1997. http://sunzi.lib.hku.hk/hkuto/record.jsp?B1904155X.
Full textThompson, Andrew S. "Experimental charactarization of flow induced vibration in turbulent pipe flow /." Diss., CLICK HERE for online access, 2009. http://contentdm.lib.byu.edu/ETD/image/etd3162.pdf.
Full textThompson, Andrew S. "Experimental Characterization of Flow Induced Vibration in Turbulent Pipe Flow." BYU ScholarsArchive, 2009. https://scholarsarchive.byu.edu/etd/1906.
Full textMark, Bill. "An experimental study of the vibration response of a single flexibly-mounted cylinder within a rigid array subjected to air cross flow /." Thesis, McGill University, 1986. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=65431.
Full textKota, Siva Kumar k. "Analysis of Heat Transfer Enhancement in Channel Flow through Flow-Induced Vibration." Thesis, University of North Texas, 2017. https://digital.library.unt.edu/ark:/67531/metadc1062854/.
Full textLiao, Jung-Chi 1971. "Vortex-induced vibration of slender structures in unsteady flow." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/8331.
Full textIncludes bibliographical references (p. 164-165).
Vortex-induced vibration (VIV) results in fatigue damage of offshore oil exploration and production structures. In recent years, the offshore industry has begun to employ curved slender structures such as steel catenary risers in deep-water offshore oil systems. The top-end vessel motion causes the slender riser to oscillate, creating an unsteady and nonuniform flow profile along the riser. The purpose of this research is to develop a VIV prediction model for slender structures under top-end periodic motions. The key approach to this problem requires identifying the dimensionless parameters important to the unsteady VIV. A set of data from a large-scale model test for highly compliant risers conducted by industry is available. The spectral analysis of the data showed a periodic pattern of the response frequencies. A constant Strouhal (St) number model was proposed such that shedding frequencies change with local inline velocities. The Keulegan-Carpenter number (KC) controls the number of vortex pairs shed per cycle. A KC threshold larger than 40 was found to have significant response for a long structure with finite length excitation region. An approximate solution to the response of an infinite beam with a finite excitation length was obtained; this solution provided an explanation for the high KC threshold. A model for an equivalent reduced damping Sg under a non-uniform, unsteady flow was proposed. This equivalent reduced damping Sg was used to establish a prediction model for the VIV under top-end periodic motions. A time domain simulation of unsteady VIV was demonstrated by using Green's functions.
(cont.) The turning point problem wave propagation was solved for a pipe resting on a linearly varying stiffness foundation. Simple rules were established for conservative estimation of TDP fatigue damage with soil interactions. Guidelines for model test experiment design were provided based on dimensional analysis and scaling rules.
by Jung-Chi Liao.
Ph.D.
Assi, Gustavo R. S. "Mechanisms for flow-induced vibration of interfering bluff bodies." Thesis, Imperial College London, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.508992.
Full textMedeiros, E. B. "An experimental study of the aeroelastic behaviour of two parallel interfering circular cylinders." Thesis, University of Salford, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.384128.
Full textCapozucca, Peter. "Flow-induced vibration of a non-constant tension cable in a sheared flow." Thesis, Massachusetts Institute of Technology, 1988. http://hdl.handle.net/1721.1/14389.
Full textPittard, Matthew Thurlow. "Large Eddy Simulation Based Turbulent Flow-induced Vibration of Fully Developed Pipe Flow." Diss., CLICK HERE for online access, 2003. http://contentdm.lib.byu.edu/ETD/image/etd295.pdf.
Full textPittard, Matthew T. "Large eddy simulation based turbulent flow-induced vibration of fully developed pipe flow /." Diss., CLICK HERE for online access, 2003. http://contentdm.lib.byu.edu/ETD/image/etd295.pdf.
Full textAllison, Anne-Marie E. "Analytical investigation of a semi-empirical flow-induced vibration model." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape15/PQDD_0014/NQ31170.pdf.
Full textMekanik, Abolghasem. "General solution for unsteady annular flows between concentric cylinders and annular flow-induced instabilities." Thesis, McGill University, 1994. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=28844.
Full textThe method of solution has been applied to various 3-D unsteady flows in annular geometries, as well as to 2-D annular flows. The numerical results obtained are compared with those based on a mean position analysis, without transformation, for small-amplitude oscillation. This comparison shows that the time-dependent coordinate transformation is necessary to obtain accurate solutions for larger-amplitude oscillations.
The mean-position approach has also been applied to the analysis of axially variable annular configurations. The results obtained show more pressure recovery after a diffuser section with 6$ sp circ$ half-angle than in the case of 20$ sp circ$ half-angle.
A comprehensive experimental study was conducted to validate the theoretical results in the range of laminar flow. The results obtained were in good agreement with the numerical results, specially with those obtained by the time-dependent coordinate transformation. Experiments were also conducted for turbulent flow.
Based on the theoretical models developed, a computational method has been used to study fluid-structure interaction phenomena. It was applied to several cylindrical annular configurations in which one side of the annulus, the outer cylinder, is assumed to be flexibly supported, and thus to be susceptible to flow-induced instabilities. The structural and N-S equations were solved simultaneously by employing the numerical method developed for the unsteady flow and a fourth-order Runge-Kutta scheme for the structural motion. The numerical results thus obtained have predicted the stability of the structure for different annular geometries. The structure having a uniform annular geometry was shown to be more damped, while the annular geometry with a backward facing step is less damped. The study of the structure for a uniform annular geometry in the case of the rocking motion of the outer cylinder predicts an instability in the form of flutter of the outer cylinder.
Thornhill, Lindsey Dorough. "Fatigue behavior of flexhoses and bellows due to flow-induced vibrations." Thesis, Georgia Institute of Technology, 1986. http://hdl.handle.net/1853/17624.
Full textVan, Zyl Marilize. "Prediction of flow-induced vibration in shell-and-tube heat exchangers." Diss., University of Pretoria, 2004. http://hdl.handle.net/2263/28055.
Full textDissertation (M Eng (Mechanical Engineering))--University of Pretoria, 2006.
Mechanical and Aeronautical Engineering
unrestricted
Kim, Chan Mun. "Vortex induced noise and vibration in flow past several flat plates /." The Ohio State University, 1989. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487673114116149.
Full textAlnujaie, Ali H. "Flow-induced Vibration of Double Wall Carbon Nanotubes Conveying Pulsating Fluid." University of Akron / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=akron1555409894074253.
Full textGrant, Ivan. "Flow induced vibrations in pipes a finite element approach /." Cleveland, Ohio : Cleveland State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=csu1274384202.
Full textAbstract. Title from PDF t.p. (viewed on June 3, 2010). Includes bibliographical references (p. 51-52). Available online via the OhioLINK ETD Center and also available in print.
Gonzalez, Enrique C. (Enrique Casaprima) 1961. "High frequency dynamic response of marine risers with application to flow-induced vibration." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/107860.
Full textPeoples, W. Wesley (William Wesley) 1977. "The effects of staggered buoyancy modules on flow-induced vibration of marine risers." Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/89915.
Full textScott, Karen Mary Louise. "Practical Analysis Tools for Structures Subjected to Flow-Induced and Non-Stationary Random Loads." Diss., Virginia Tech, 2011. http://hdl.handle.net/10919/38686.
Full textPh. D.
Yin, Decao. "Experimental and Numerical Analysis of Combined In-line and Cross-flow Vortex Induced Vibration." Doctoral thesis, Norges teknisk-naturvitenskapelige universitet, Centre for Ships and Ocean Structures, 2013. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-20014.
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