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Hajghayesh, Mergen. "Dynamics of fluid-conveying pipes." Thesis, McGill University, 2013. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=114479.
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This thesis studies the linear and nonlinear dynamics of pipes conveying fluid. It consists of four peer-reviewed journal papers, three published and one submitted for publication. The aim is to investigate aspects of the dynamical behaviour of extensible and inextensible pipes conveying fluid, both theoretically and experimentally.In particular, (i) the three-dimensional nonlinear dynamics of a pipe conveying fluid, constrained by an array of four springs attached at a point along its length is examined from the theoretical and experimental perspectives; (ii) the three-dimensional dynamical behaviour of a fluid-conveying cantilevered pipe fitted with an end-mass and additional intra-span spring support is investigated, both theoretically and experimentally; (iii) the nonlinear planar dynamics of a cantilevered extensible pipe conveying fluid is investigated theoretically via two different numerical techniques; (iv) the phase-shift along the length of the measuring pipe of a Coriolis mass-flowmeter is developed (and thus mass-flow rate is determined) analytically by means of a perturbation technique and confirmed numerically. In the theoretical analyses, the Galerkin method and Lagrange equations for systems containing non-material volumes are employed to obtain a set of nonlinear second-order ordinary differential equations. These equations are solved by means of Houbolt's finite difference scheme, the pseudo-arclength continuation technique, and direct time integration via a modified Rosenbrock technique. The method of multiple timescales, an approximate analytical technique, is also used to predict the phase-shift along the length of the measuring pipe of a Coriolis mass-flowmeter.A series of experiments were conducted with silicone rubber pipes conveying water, and thereby the theoretical models have been broadly validated.Cette thèse traite de la dynamique linéaire et non linéaire de tuyaux parcourus par un fluide. Composée de quatre articles scientifiques ayant fait l'objet d'un examen critique, trois publiés dans des revues techniques et un soumis pour publication, l'objectif étant d'étudier certains aspects du comportement dynamique des conduits extensibles et inextensibles transportant du fluide, de manière théorique et expérimentale.En particulier, (i) la dynamique tridimensionnelle non linéaire d'un tuyau de transport de fluide, contraint par un réseau de quatre ressorts attachés entre les deux bouts est examinée d'un point de vue théorique ainsi qu'expérimental; (ii) le comportement dynamique tridimensionnel d'un tuyau aux extrémités encastrées-libres avec une masse additionnelle au bout libre et un support flexible (ressort) supplémentaire, est également étudié; (iii) la dynamique non linéaire plane d'un tuyau extensible encastre-libre transportant du fluide est étudiée théoriquement par deux méthodes numériques différentes; (iv) le calcul du déphasage sur la longueur du conduit de mesure d'un débitmètre à effet Coriolis (et donc, du débit massique) est mis au point analytiquement au moyen d'une technique de perturbation et est confirmé numériquement. Lors des analyses théoriques, la méthode de Galerkin et les équations de Lagrange pour les systèmes contenant des volumes vides sont utilisés pour obtenir un ensemble d'équations différentielles ordinaires non-linéaires du second ordre. Ces équations sont résolues grâce à un schéma de différences finies de Houbolt, la technique de continuation à pseudo-longueur d'arc, et l'intégration temporelle directe par l'intermédiaire d'une technique de Rosenbrock modifiée. La méthode des délais multiples (dite "multiple scale method"), une technique analytique approximative, est également utilisée pour prédire le déphasage le long du tuyau de mesure d'un débitmètre à effet Coriolis.Une série d'expériences ont été réalisées à l'aide de tuyaux en silicone transportant de l'eau afin de pouvoir vérifier de manière concluante la validité des modèles théoriques.
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Petrus, Ryan Curtis. "Dynamics of fluid-conveying Timoshenko pipes." Texas A&M University, 2006. http://hdl.handle.net/1969.1/3822.
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Structures conveying mass lose stability once the mass exceeds a certain critical
velocity. The type of instability observed depends on the nature of the supports that the
structure has. If the structure (beam or pipe) is cantilevered (thereby deeming it a nonconservative
system), Âgarden-hose-like flutter instability is observed once a critical
velocity is exceeded. When studying the flutter instability of a cantilevered pipe
(including shear deformation) by strictly a linear theory, it has been demonstrated
through numerical integration that the values of the critical velocity are only valid for
small values of the mass ratio (mass of the fluid divided by the total mass)
(approximately 0.1 β< ). This fact is also true if shear deformation is neglected. Also,
linear theory predicts the pipe to oscillate unboundedly as time progresses, which is
physically impossible. Therefore, shortly after the pipe goes unstable, the linear theory
is no longer applicable. If non-linear terms are taken into account from the beginning, it
can be shown that the pipe oscillates into a limit cycle.
3
Van, Ke Sum. "Dynamics and stability of curved pipes conveying fluid." Thesis, McGill University, 1986. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=66108.
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Champneys, Alan R. "The nonlinear dynamics of articulated pipes conveying fluid." Thesis, University of Oxford, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.302850.
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Giacobbi, Dana. "The dynamics of aspirating cantilevered pipes and pipes conveying variable density fluid." Thesis, McGill University, 2010. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=95074.
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This thesis undertakes the investigation of the dynamics of two different cases of a slender, flexible pipe conveying fluid: (i) an aspirating cantilevered pipe, ingesting fluid at its free end and transporting it towards the clamped end, and (ii) a pipe conveying a fluid whose density varies axially along the length of the pipe. The general context of the research is first provided by broadly introducing the field of Fluid-Structure Interactions (FSI) and reviewing the basic theory regarding pipes conveying fluid. Subsequently, a numerical approach coupling Computational Fluid Dynamics (CFD) and Computational Structural Mechanics (CSM) to simulate each system is developed in ANSYS. Lastly, the linear equation of motion is derived for each system and solved using a Galerkin approach; the numerical experiments are then combined with these analytical results to determine the stability characteristics of each system. The problem of an aspirating cantilevered pipe is of both fundamental and practical interest, with applications, for example, in deep sea ocean mining. The motivation for a continued study of the system is demonstrated through a review of previous research on the topic spanning many years and yielding often contradictory results. The newly proposed analytical model, derived using a Newtonian approach and heavily influenced by CFD analysis, is different from previous ones, most notably because of the inclusion of a two-part fluid depressurization at the intake. In this case, the combined numerical and analytical approaches suggest a first-mode loss of stability by flutter albeit a very weak one at comparable but usually lower flow velocities than the discharging cantilever. In the case of a pipe conveying variable density fluid, the analytical model is derived using a Hamiltonian approach, for (i) a pipe clamped at both ends and (ii) a cantilevered pipe. It is shown that these systems lose stability by buckling and flutter respectively, simiCette thèse entreprend l'étude de la dynamique de deux types de tuyaux flexibles parcourus par un fluide : (i) un tuyau encastré-libre aspirant le fluide du côté libre et l'amenant vers le côté encastré, et (ii) un tuyau transportant un fluide dont la densité varie axialement au long du tuyau. Le contexte général de cette recherche est d'abord présenté en introduisant le domaine des Interactions fluide-structure (FSI) et en révisant la théorie de base des tuyaux transportant un fluide. Par la suite, une approche numérique couplant la simulation des fluides (CFD) et des structures mécaniques (CSM) est développée dans ANSYS. Dernièrement, une équation de mouvement linéaire est dérivée pour chaque système et analysée par une méthode Galerkin; les résultats numériques sont enfin combinés avec ces résultats analytiques pour déterminer les caractéristiques de stabilité de chaque système. Le tuyau encastré-libre aspirant est d'un intérêt fondamental et aussi pratique, possédant des applications, entre autres, dans l'industrie minière sous-marine. La raison d'une étude poursuivie est démontrée par un retour sur la recherche antérieure traitant du sujet s'étendant sur plusieurs années et produisant souvent des résultats contradictoires. Le nouveau model analytique, dérivé utilisant une approche Newtonienne et largement influencé par une analyse CFD, se distingue de ses prédécesseurs notamment par l'inclusion d'une dépressurisation en deux parties à l'entrée. Pour ce cas, les approches numérique et analytique suggèrent tous les deux une perte de stabilité par flottement dans le premier mode quoiqu'une instabilité très faible à des vitesses comparables, mais généralement moindre que le cas déchargeant. Dans le cas d'un tuyau transportant un fluide de densité variable, le modèle analytique est dérivé à l'aide d'une approche Hamiltonienne, pour des tuyaux (i) encastré-encastré et (ii) encastr
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Muoka, Anthony E. "Dynamics of three-dimensional pipes conveying fluid using the Reissner beam theory." Thesis, Swansea University, 2018. https://cronfa.swan.ac.uk/Record/cronfa48136.
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The study of dynamics of pipes conveying fluid has been the subject of research for many decades now, and various formulations, solution methodologies and applications have been developed. The topic is well understood but research in this area is ongoing as the study of the subject is far from trivial. This is a classical model problem in the study of dynamics and stability of structures mainly because it is a physically simple system capable of displaying a wide array of interesting behaviour in both the linear and nonlinear regime. In this thesis, a geometrically exact fully implicit version of the 3D beam element, which employs the Rodrigues formula for the update of large rotations is used in the solution of the equations of motion. The nonlinear model for the flexible beam conveying fluid has been formulated and implemented to recover the interesting dynamic behaviour of the system in 3D. The advantage of this approach stems mainly from the fact that approach to engineering problems depends upon the intended application, cost from a computational perspective, among other factors which may be taken into consideration, and this provides an alternative to existing approaches. Benchmark problems are presented in 2D and 3D, and confirm robustness and accuracy of the formulation.
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Lumijärvi, J. (Jouko). "Optimization of critical flow velocity in cantilevered fluid-conveying pipes, with a subsequent non-linear analysis." Doctoral thesis, University of Oulu, 2006. http://urn.fi/urn:isbn:9514280687.
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Abstract
This study deals with optimal design of cantilevered fluid-conveying pipes. The aim is to maximize the critical flow speed of the fluid by means of additional masses, supporting springs or dampers along the length of the pipe.
The optimization problem was formulated by modelling the pipe by FEM, using Euler-Bernoulli beam elements. The locations of the additional masses, springs and dampers and the properties of these elements (mass, spring constant and damping constant) were chosen as design parameters. The maximization problem for the critical fluid flow speed was solved by the sequential quadratic programming (SQP) technique.
In addition to the presentation of the optimal values obtained for the design parameters, some aspects of the sensitiveness of the systems to variations in these parameters and the robustness of the optimum designs with respect to the stability of the system are studied.
Although a considerable increase in the critical flow velocity of the fluid can be achieved in the example cases studied here, a marked sensitivity of the system to the location and properties of the additional elements in the optimum designs was observed. Also, the margin with respect to stability seems to be relatively small in some of the optimum designs considered.
Non-linear numerical analysis confirmed the findings of the linear analysis with respect to the sensitivity of the optimum designs to the properties of the additional elements and revealed a very rich post-critical dynamic behaviour in the optimized structures.
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Semler, Christian 1966. "Nonlinear dynamics and chaos of a pipe conveying fluid." Thesis, McGill University, 1991. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=60586.
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This thesis examines the planar dynamics of flexible pipes conveying fluid. The nonlinear equations of motion are derived for cantilevered pipes and for simply-supported pipes, using Hamilton's principle and the force balance method. The resulting equations are compared with previous derivations.The linearized system is first studied, to get the critical parameters corresponding to the stability boundaries, i.e. the local bifurcations. Then, the nonlinear equations are investigated, both analytically and numerically. Centre manifold, normal form and bifurcation theories are used to obtain complete bifurcation sets which provide the qualitative dynamics of the system. It is shown that chaotic motions may arise under perturbation, or when the motions are constrained by motion-limiting restraints, through calculations of the Lyapunov exponents and the construction of phase portraits, bifurcation diagrams and power spectra. This modeling is in close agreement with experimental observations.
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張峻榮. "Optimal Design of Fluid-Conveying Pipes." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/79639577701653371653.
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碩士國立海洋大學
機械與輪機工程學系
91
The purpose of this study is to investigate the dynamic characteristics and optimal design of pipes conveying fluid. Finite element method is applied to establish the equations of motions of both the uniform and the tapered fluid-conveying pipes. The established models are verified by using the results reported in the literature. To fully understand the system dynamic characteristics, root loci of the system are plotted to investigate the system stability properties. Sequential quadratic programming (SQP) is applied for the optimal design of pipes conveying fluid. This study shows that although root loci can be used to examine the modal stability properties, the modal vector information must be utilized to determine which mode is unstable when modes get to come across each other as the flow speed varies. For optimal design, it is demonstrated that significant improvement can be achieved for both the cases of minimization of pipe weight given a fixed critical flow speed and maximization of critical flow speed given a fixed pipe weight. The analysis is thus proved to be beneficial to engineering design and economical considerations.
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Wang, Yi-Wen, and 王義文. "Analysis of Optimal Attachment Positions for Pipes Conveying Fluid." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/99514041990465907219.
Full textAbstract:
碩士國立臺灣海洋大學
機械與機電工程學系
94
The purpose of this study is to analyze the optimal attachment positions for pipes conveying fluid. The finite element model is established and then simulated under the conditions of different fluid-beam mass ratios. By adding various attachments on different positions of the cantilever pipes conveying fluid, the optimal values and positions of the attachments can be obtained for achieving the highest critical flow velocity. The attachments used in this study are dampers and springs. The goal is to establish the critical flow velocity trend chart of the single attachment condition and to search the optimal parameters effectively by using the genetic algorithm. Furthermore, optimal design for the two-attachment case is also analyzed in this work. The analysis results reveal the optimal attachment positions vary with different mass ratios. As the fluid mass becomes larger, the best condition changes from the single-damper case (β=0.1 to 0.5) to the single-spring case (β=0.6 to 0.9). The critical flow velocity of the two-damper case is higher than that of the single-damper case. Similarly, the use of two-spring performs better than the use of single-spring. The two-damper case with β=0.1 to 0.6 is found to have the best performance. The use of one damper and one spring performs better for β=0.7 to 0.8. The two-damper case yields essentially identical results with those of the two-spring case at β=0.9. As compared with the incremental method for the analysis of one attachment case, the genetic algorithm is far superior in terms of computational time. For the case of multiple attachments, it is impractical to use the incremental method, whereas the genetic algorithm is still applicable and possess superior performance. Keyword : pipes conveying fluid, attachment, optimal design
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Tsai, Yau-Kun, and 蔡耀坤. "Nonlinear Dynamic Analysis and Vibration Control of Fluid- Conveying Pipes." Thesis, 1996. http://ndltd.ncl.edu.tw/handle/26854663335083114696.
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碩士國立海洋大學
機械與輪機工程學系
84
ABSTRACT The purpose of this study was to investigate the non- linear dynamic behavior and vibration control of beam structures conveying fluid. Finite element analysis of beams with immovable ends involving geometric non- linearity was studied first. Both the effects of shearing deformations and rotary inertia, known as Timoshenko beam theory, were considered. Simple linear functions were used to interpolate the displacement fields within an element. Reduced order integration was applied to alleviate the problem of shear locking. Excellent agreement was observed when comparing the present analysis results with those available in the literature for the analysis of slender beams. For short beam analysis, correct analysis procedure was presented and the improvement over the use of a linearizing function was addressed. The non-linear dynamic behavior of beams conveying fluid was analyzed next. The concept of fictitious loads was applied to establish the system model so that convergence characteristics can be improved and the use of various load steps is no longer required for non-linear finite element analysis. The analysis was based on the use of linear matrix equations without the need to consider the higher order terms for non-linear analysis, which simplified the analysis procedure. The limit cycle phenomenon was correctly predicted in this work, which is unobtainable using the linear analysis. The present work was verified by comparing results with those available in the literature. Further analysis was conducted to investigate the influences of system parameters on the limit cycle characteristics. As for the problems of vibration control, both the linear and non-linear controls were considered. For linear control, the optimal independent modal space control (IMSC) and the adaptive independent modal space control were presented. The IMSC controller is designed in modal space with decoupled equations, hence the intensive computation when using the traditional coupled mode control is greatly reduced. The differences of the two control techniques were discussed. It was observed that the adaptive independent modal space control has better robustness characteristics for varying flow speeds; that is the controller can tolerate larger variation of system parameters. For non-linear control, the instantaneous optimal control technique was applied, which optimizes the control input at every instant without the need to solve for the non-linear Riccati matrix equations. The vibration control performance for flow speed higher than the critical one was examined. Control of vibrations due to both the fluid motion a nd base excitation was addressed. The influence of actuator locations on the control performance was also analyzed to provide a design guideline for the control system.
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FAN, JING-NAN, and 范景南. "Analysis of secondary flow and dynamic characteristics of pipes conveying fluid." Thesis, 1987. http://ndltd.ncl.edu.tw/handle/58024853732758398337.
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Ho, Chen Yi, and 何建毅. "Stability Analysis and Vibration Control of Pipes Conveying Fluid with Time-varying Flow Speeds." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/22865124581238757295.
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碩士國立海洋大學
機械與輪機工程學系
86
Dynamic analysis and control of pipes conveying time- varyingfluid is examined in this work. A finite element model is developedfor the moving fluid. For stability analysis, a finite element modelwhich includes the effects of shearing deformations and rotary inertia, know as Timoshenko beam theory, is applied. The force due to the axial accleration is include for analysis. The stability condition, defined by the flow variation frequency and the variation amplitude, are determined by using the Bolotin's method. The procedure isdifferent from the pronlem with a constant flow speed where the stabilitycan be analyzed by using the root locus plot. The size and position of the stability region are dependent of the system parameters. Ina numberical example, good agreement is observed between the analysisresults of this work and those of the literature for slender pipes.the dependence of the stability region and system parameters, shchas mean flow speed, mass ratio, slenderness ratio, is examined in thiswork. A direct feedback control approach is applied to investigatethe stability properties of pipes conveying time-varying fluid. Thesize and position of the stability region are examined by using anactuator with velocity and/or displacement feedback. The effect ofactuator position on stability of the system is analyzed. The ModelReference Adaptive Control(MRAC) approach is also applied for activevibration control suppression of the pipe system. For pipes conveyingtime- varying fluid, flutter may occur even when the flow speed is below the critical one as for a constant flow speed problem. The MRACis applied in this study to supress flutter. It is shown the approachis robust for a system with variations, unknown to the control system,of mean velocity, amplitude, and frequency. The control system can stillbe operational without changing the control parameters for a system withparameter uncertainties. A numberical example is given to demonstratethe robustness of the MRAC approach for vibration suppression of pipesconveying time- varying fluid with the mean flow speed below the criticalone.
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Ting-YuChang and 張廷宇. "Dynamic analyses of the fluid-conveying pipes on elastic foundation and subjected to distributed load." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/39167948191869846732.
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碩士國立成功大學
系統及船舶機電工程學系碩博士班
101
This purpose of this thesis is to study the vibration problem of the fluid-conveying pipes resting on the elastic Winkler foundations. Since the beam is one of the most popular structural members and the dynamic characteristic of a fluid-conveying pipe is similar to that of a beam carrying flowing fluid, this thesis derives the equation of motion of a fluid-conveying pipe by means of the Euler-Bernoulli beam theory. Next, the influences on the free-vibration characteristics of some parameters such as supporting conditions of the pipe, the stiffness of the elastic foundation, fluid velocity and Coriolis force due to flowing fluid are studied. Finally, the forced vibration responses of the fluid-conveying pipe due to distributed external forces are investigated. In this thesis, the dynamic responses of the fluid-conveying pipes are performed by using the finite element method (FEM), thus, the essential work is to derive the property matrices of the fluid-conveying pipe. To this end, the kinetic energy and potential energy of a pipe element are determined first and then substituted into the Lagrange equation to obtain the mass matrix, damping matrix and stiffness matrix of the pipe element. The assembly of the latter element property matrices will determine the corresponding overall ones of the entire fluid-conveying pipe system. Finally, for the case of neglecting Coriolis force, the natural frequencies and the corresponding mode shapes are obtained by using the Jacobi method, and, for the case of considering Coriolis force, the free vibration analysis is conducted by using the software of EISPAK. As to the forced vibration analysis, the time histories and the frequency-response amplitude curves for any point on the fluid-conveying pipe are determined by using the Newmark’s direct integration method.
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"Effects of Structural Uncertainty on the Dynamic Response of Nearly-Straight Pipes Conveying Fluid: Modeling and Numerical Validation." Master's thesis, 2017. http://hdl.handle.net/2286/R.I.45028.
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abstract: This investigation is focused on the consideration of structural uncertainties in nearly-straight pipes conveying fluid and on the effects of these uncertainties on the dynamic response and stability of those pipes. Of interest more specifically are the structural uncertainties which affect directly the fluid flow and its feedback on the structural response, e.g., uncertainties on/variations of the inner cross-section and curvature of the pipe. Owing to the complexity of introducing such uncertainties directly in finite element models, it is desired to proceed directly at the level of modal models by randomizing simultaneously the appropriate mass, stiffness, and damping matrices. The maximum entropy framework is adopted to carry out the stochastic modeling of these matrices with appropriate symmetry constraints guaranteeing that the nature, e.g., divergence or flutter, of the bifurcation is preserved when introducing uncertainty.
To support the formulation of this stochastic ROM, a series of finite element computations are first carried out for pipes with straight centerline but inner radius varying randomly along the pipe. The results of this numerical discovery effort demonstrate that the dominant effects originate from the variations of the exit flow speed, induced by the change in inner cross-section at the pipe end, with the uncertainty on the cross-section at other locations playing a secondary role. Relying on these observations, the stochastic reduced order model is constructed to model separately the uncertainty in inner cross-section at the pipe end and at other locations. Then, the fluid related mass, damping, and stiffness matrices of this stochastic reduced order model (ROM) are all determined from a single random matrix and a random variable. The predictions from this stochastic ROM are found to closely match the corresponding results obtained with the randomized finite element model. It is finally demonstrated that this stochastic ROM can easily be extended to account for the small effects due to uncertainty in pipe curvature.Dissertation/Thesis
Masters Thesis Mechanical Engineering 2017
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Silva, Rui. "Solid/liquid suspension flow in pipes: modelling and experimental investigation." Doctoral thesis, 2015. http://hdl.handle.net/10316/27962.
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Tese de doutoramento em Engenharia Química, apresentada à Faculdade de Ciências e Tecnologia da Universidade de CoimbraWith this thesis the leading objective was to study the complex behaviour of solid-liquid suspensions pipeline conveying. To that regard, experimental and numerical studies were both conducted. Experimental data was acquired in the form of velocity profiles for both the liquid and solid phases employing Magnetic Resonance Imaging (MRI) and Ultrasonic Pulse Velocimetry (UPV), respectively, for a range of experiments with several sizes and concentrations of settling particles. Moreover, in order to attain the particle distribution in the pipeline, which is one of more prominent variables in solid-liquid suspensions flow, a new Electrical Impedance Tomography (EIT) system was developed: this type of systems use the distribution of electrical conductivity in a domain has is principle of development. The Mixture Model was implemented in the numerical studies using Computational Fluid Dynamics (CFD) simulations in an attempt to replicate the experimental data that resulted from the aforementioned experiments. Additionally, experimental data for highly concentrated buoyant and settling particles, existent in the literature, where complex phenomena like turbulence attenuation and particle migration occur, was also simulated by means of the Mixture Model. The EIT apparatus displayed the capability of recognizing the different flow regimes and particle concentration variations in the pipeline. Furthermore, the images and profiles gathered in these experiments, with the three experimental techniques mentioned above, accurately matched the numerical results from the CFD model, thus validating it for the study of solid-liquid suspensions flows.
Esta tese tinha como grande objectivo o estudo do escoamento de suspensõ es só lido-lı́quido recorrendo em simultâ neo a testes experimentais e numé ricos. Dados experimentais sob a forma de perfis de velocidade do meio lı́quidos e das partı́culas empregando Imagens por Ressonância Magnética (IRM) e Velocimetria de Pulso Ultra-sónico (VPU), respectivamente, foram obtidos para uma gama variada de tamanhos e concentrações de partıć ulas. Conjuntamente, um sistema de Tomografia de Impedância Eléctrica (TIE) foi desenvolvido com vista à obtenção da distribuição de partı́culas na conduta, sistema que utiliza a distribuiçã o da condutividade elé ctrica num determinado meio como base do seu funcionamento. A distribuiçã o de sólidos é uma das variáveis mais importantes no escoamento de suspensões só lido-lı́quido. Os estudos numéricos foram realizados utilizando o Modelo de Mistura atravé s de Dinâ mica de Fluidos Computacional (DFC) na tentativa de reproduzir os dados resultantes das experiê ncias mencionadas acima. Adicionalmente, dados da literatura para escoamentos de suspensões sólido- lı́quido concentradas, para partı́culas neutras e pesadas, com comportamentos complexos como atenuação da turbulência e migração de partı́culas, foram també m simulados utilizando o Modelo de Mistura. O sistema de TIE demonstrou a capacidade de reconhecer diferentes regimes de escoamento e variações na concentração de partı́culas na conduta com precisã o. Alé m disso, as imagens e perfis obtidos com as trê s té cnicas experimentais previamente citadas foram semelhantes aos resultados numé ricos obtidos com o Modelo de Mistura, validando assim a sua aplicaçã o em estudos de escoamento de suspensõ es só lido-lı́quido. Finalmente, a atenuação da turbulência induzida pelas partı́culas foi caracterizada com sucesso atravé s das modificaçõ es implementadas no Modelo de Mistura.
SFRH/BD/79247/2011
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Yang, Wei-Min, and 楊維泯. "The Dynamic Analysis of A Multi-span Pipe Conveying Fluid." Thesis, 1996. http://ndltd.ncl.edu.tw/handle/64088930288385045731.
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Hsu, Wei-Liang, and 徐維良. "Optimal Digital Modal Vibration Suppression of a Cantilever Pipe Conveying Fluid." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/60259608262787332135.
Full textAbstract:
碩士國立臺灣海洋大學
機械與機電工程學系
99
The purpose of this research is to investigate digital vibration control of a cantilever pipe conveying fluid considering modal observer dynamics. Firstly, with the classical beam theory being considered, the pipe and the actuator dynamics are taken into account for establishing the system's equations of motion for the control formulation. The computation of the feedback gain is realized by discrete time optimal control theory. A method for generating the close loop eigenvectors with the target values is also proposed. It is impractical to measure all the system states. The application of an observer can be used to alleviate the burden by estimating the required modal states used for feedback control. This study used a single sensor, along with the application of a modal space observer, and applied the modified IMSC (independent modal space control) formulation for structural vibration suppression. The advantage of being able to direct the control on the unstable mode only can reduce the computation cost significantly. From the numerical evaluation, the proposed method using only the controlled modal feedback signals can stabilize the originally unstable system and provides great control performance.
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Chang, Lee-Jen, and 張力仁. "Analysis of vibration absorption of pipe conveying fluid with vibration-damper." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/02841881004827931234.
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Yang, Ji-Hua, and 楊濟華. "Simultaneous Optimization of the Structure and Control System for Pipes Conveying Fluids." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/55776592319577858664.
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碩士國立臺灣海洋大學
機械與輪機工程學系
92
ABSTRACT The purpose of this research is to study the simultaneous optimization of structure and control system for pipes conveying fluids. Finite element method is applied to establish the equations of motions of both the uniform and the tapered fluid-conveying pipes with over critical flowing speed and divergence characteristics. Active vibration control for suppressing the excessive structural vibration is considered. Sequential quadratic programming is applied for the optimal design. The effects of shearing deformation and rotary inertia are included. Optimal independent modal space control (IMSC) is applied for the design. Genetic Algorithms,used for optimization of taper pipe,is found to be much faster than the SQP approach. As far as simultaneous optimization of the structure and control system is concerned the effect of the control energy upper bound on the critical flow speed and the optimal shape of the fluid-conveying pipes will be examined.
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Huang, Rui-Cheng, and 黃瑞成. "Independent Modal Space Control a Fluid-conveying Pipe with a Divergent Mode." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/26508299166704275607.
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碩士國立海洋大學
機械與輪機工程學系
88
The purpose of this research is to study the divergence characteristics of pipes conveying fluid and to explore the applicability of active vibration control for suppressing the associated excessive structural vibration. The Timoshenko beam theory is used to establish the system equation of motion. The analysis is based on the finite element method. The effects of shearing deformation and rotary inertia are included so that the analysis is applicable for short sturdy beams or for higher mode study. Active vibration control technique is developed in this work for pipes conveying fluid with a flow speed exceeding the critical one. Optimal independent modal space control (IMSC) is applied for the design. For pipes conveying supercritical flow speed, the system possesses both real and complex modes, which must be dealt with in different ways. A weighting matrix with finite weight is applied for the control of complex modes, whereas a weighting matrix with an infinite weight is used for controlling the real modes, the divergent modes. From this study, it is demonstrated that the control approach proposed in this work can ensure closed loop stability. The mode switching scheme during control implementation is found to be beneficial in reducing the steady state vibration of the fluid-conveying pipes.
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Huang, Bo-Chuang, and 黃柏創. "Active Vibration Suppression of a Cantilever Pipe Conveying Fluid Considering Modal Observer Dynamics." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/84665290040507524441.
Full textAbstract:
碩士國立臺灣海洋大學
機械與機電工程學系
98
The purpose of this thesis was to investigate vibration control of a cantilever pipe conveying fluid considering modal observer dynamics. The pipe and the actuator dynamics were taken into account to establish the system’s equations of motion for the control formulation. It is impractical to measure all the system states. The application of an observer can be used to alleviate the burden by estimating the required modal states used for feedback control. This study used a single sensor, along with the application of a modal space observer, and applied the modified IMSC (independent modal space control) formulation for structural vibration suppression. The advantage of being able to direct the control on the unstable mode only can reduce the computation cost significantly. In addition, a systematic stability analysis was performed by using the direct feedback control. The associated limiting flow speeds were presented to illustrate the unattainable closed loop stability. The modified IMSC along with the modal observer proposed in this study was applied to overcome the dilemma and to demonstrate its superior control performance.
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Chen, Jui-Lung, and 陳瑞龍. "Vibration control of a cantilever pipe conveying fluid using a piezoelectric inertia actuator." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/43484796412423380470.
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Liu, Tung-Wen, and 劉童文. "Optimal independent modal space control of a fluid-conveying cantilever pipe with flutter instability." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/37678420974307364203.
Full textAbstract:
碩士國立臺灣海洋大學
機械與機電工程學系
95
This study deals with the active vibration control of cantilever pipes conveying fluid. The structural instability, such as flutter of a cantilever pipe, will occur due to conveying super-critical flow speed. Both the pipe and the actuator dynamics are considered for establishing the system’s equations of motion for the control formulation. The structural vibration is controlled by using the independent modal space control (IMSC) approach which has the advantages of being able to direct the control on the unstable mode only, reducing the computation significantly, and greatly decreasing the storage requirement. This study deals with a system possessing complex modes, with the unstable mode’s real part being bigger than the imaginary part. This disables the applicability of one important modified IMSC formulation, and the pioneers’ approach, unfavorable in the general cases, must be applied to overcome the difficulties. This study reveals, for the first time, the applicable stability analysis for the development proposed by the IMSC pioneers and turns the table around by changing the originally unfavorable control characteristics to become a favorable one.
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Chen, Chun-Hsin, and 陳群欣. "Dynamic Analysis of a Horizontal Multispan Fluid Conveying Pipe with the Effects of Shear Deformation and Rotatory Inertia." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/32821633110025867906.
Full textAbstract:
碩士國立成功大學
造船工程學系
85
The dynamic resposes of a horizontal multispan fluid conveying pipe with the effects of shear deformation and rotatory inertia are studied by means of the quasi analytical- and-numerical-combined method (quasi ANCM). First of all,instead of seeking the (exact) closed-form solution analytical for the naturl frequencies and normal mode shapes of the "unconstrained" fluid conveying pipe (with carrying any constrained elements)when fluid velocity equal zero required for pure ANCM,the natural frequencies together with the normal mode shapes for the quasi ANCM are obtain numerically,however. By applying the expansion theorem and the mode superposition methodology,then the approximate natural frequencies and mode shapes of fluid conveying pipe with the effect of fluid velocity are obtained numerically by Jacobi method.Finally its dynamic responses are calculated numerically by Newmark method.