Analysis of Induced Vibrations in Fully-developed Turbulent Pipe Flow Using a Coupled LES and FEA Approach PDF Download
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Author: Thomas P. Shurtz
Publisher:
ISBN:
Category : Electronic dissertations
Languages : en
Pages : 130
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Book Description
Turbulent flow induced pipe vibration is a phenomenon that has been observed but not fully characterized. This thesis presents research involving numerical simulations that have been used to characterize pipe vibration resulting from fully developed turbulent flow. The vibration levels as indicated by: pipe surface displacement, velocity, and acceleration are characterized in terms of the parameters that exert influence. The influences of geometric and material properties of the pipe are investigated for pipe thickness in the range 1 to 8 mm at a diameter of 0.1015 m. The effects of pipe elastic modulus are explored from 3 to 200 GPa. The range of pipe densities investigated is 3,000 to 12,000 kg/m3. All pipe parameters are varied for both a short pipe (length to diameter ratio = 3) and a long pipe (length to diameter ratio = 24). Further, the effects of varying flow velocity, fluid density and fluid viscosity are also explored for Reynolds numbers ranging from 9.1x104 to 1.14x106. A large eddy simulation fluid model has been coupled with a finite element structural model to simulate the fluid structure interaction using both one-way and two-way coupled techniques. The results indicate a strong, nearly quadratic dependence of pipe wall acceleration on average fluid velocity. This relationship has also been verified in experimental investigations of pipe vibration. The results also indicate the pipe wall acceleration is inversely dependant on wall thickness and has a power-law type dependence on several other variables. The short pipe and long pipe models exhibit fundamentally different behavior. The short pipe is not sensitive to dynamic effects and responds primarily through shell modes of vibration. The long pipe is influenced by dynamic effects and responds through bending modes. Dependencies on the investigated variables have been non-dimensionalized and assembled to develop a functional relationship that characterizes turbulence induced pipe vibration in terms of the relevant parameters. The functional relationships are presented for both the long and short pipe models. The functional relationships can be used in applications including non-intrusive flow measurement techniques. These findings also have applications in developing design tools in pipe systems where vibration is a problem.
Author: Thomas P. Shurtz
Publisher:
ISBN:
Category : Electronic dissertations
Languages : en
Pages : 130
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Book Description
Turbulent flow induced pipe vibration is a phenomenon that has been observed but not fully characterized. This thesis presents research involving numerical simulations that have been used to characterize pipe vibration resulting from fully developed turbulent flow. The vibration levels as indicated by: pipe surface displacement, velocity, and acceleration are characterized in terms of the parameters that exert influence. The influences of geometric and material properties of the pipe are investigated for pipe thickness in the range 1 to 8 mm at a diameter of 0.1015 m. The effects of pipe elastic modulus are explored from 3 to 200 GPa. The range of pipe densities investigated is 3,000 to 12,000 kg/m3. All pipe parameters are varied for both a short pipe (length to diameter ratio = 3) and a long pipe (length to diameter ratio = 24). Further, the effects of varying flow velocity, fluid density and fluid viscosity are also explored for Reynolds numbers ranging from 9.1x104 to 1.14x106. A large eddy simulation fluid model has been coupled with a finite element structural model to simulate the fluid structure interaction using both one-way and two-way coupled techniques. The results indicate a strong, nearly quadratic dependence of pipe wall acceleration on average fluid velocity. This relationship has also been verified in experimental investigations of pipe vibration. The results also indicate the pipe wall acceleration is inversely dependant on wall thickness and has a power-law type dependence on several other variables. The short pipe and long pipe models exhibit fundamentally different behavior. The short pipe is not sensitive to dynamic effects and responds primarily through shell modes of vibration. The long pipe is influenced by dynamic effects and responds through bending modes. Dependencies on the investigated variables have been non-dimensionalized and assembled to develop a functional relationship that characterizes turbulence induced pipe vibration in terms of the relevant parameters. The functional relationships are presented for both the long and short pipe models. The functional relationships can be used in applications including non-intrusive flow measurement techniques. These findings also have applications in developing design tools in pipe systems where vibration is a problem.
Author: Matthew Thurlow Pittard
Publisher:
ISBN:
Category : Eddies
Languages : en
Pages : 156
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Book Description
Flow-induced vibration caused by fully developed pipe flow has been recognized, but not fully investigated under turbulent conditions. This thesis focuses on the development of a numerical Fluid-Structure Interaction (FSI) model that will help define the relationship between pipe wall vibration and the physical characteristics of turbulent flow. Commercial FSI software packages are based on Reynolds Averaged Navier-Stokes (RANS) fluid models, which do not compute the instantaneous fluctuations in turbulent flow. This thesis presents an FSI approach based on Large Eddy Simulation (LES) flow models, which do compute the instantaneous fluctuations in turbulent flow. The results based on the LES models indicate that these fluctuations contribute to the pipe vibration. It is shown that there is a near quadratic relationship between the standard deviation of the pressure field on the pipe wall and the flow rate. It is also shown that a strong relationship between pipe vibration and flow rate exists. This research has a direct impact on the geothermal, nuclear, and other fluid transport industries.
Author: Donald O. Barnett
Publisher:
ISBN:
Category : Laminar flow
Languages : en
Pages : 68
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Book Description
An analysis is presented of the effect of longitudinal pressure pulsations or vibrations on the velocity distribution in laminar or turbulent fully developed pipe flow. Specifically, the Reynolds equations are formulated in a noninertial reference frame so that the influence of pressure pulsations, vibrations, or a combined pressure and vibrational oscillation can be obtained from a single solution. For axisymmetric developed flow of a constant property (incompressible) fluid, the radial and circumferential momentum equations can be solved and the axial momentum equation is linearized so that the velocity field can be obtained as the sum of a steady and a time-dependent component. By obtaining a solution for the case where the pressure (or amplitude of vibration) varies sinusoidally, one obtains the solution for disturbances of arbitrary waveform through a Fourier series expansion of the disturbance. Results are presented that show that the velocity field is dependent upon the mean flow Reynolds number, a vibrational Reynolds number, and the amplitude of the forcing function. In general, the fluid response to differing waveforms is similar to that obtained for simple harmonic oscillations with respect to the various parameters explored.
Author: Ivan Grant
Publisher:
ISBN:
Category : Finite element method
Languages : en
Pages : 74
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Book Description
Flow induced vibrations of pipes with internal fluid flow is studied in this work. Finite Element Analysis methodology is used to determine the critical fluid velocity that induces the threshold of pipe instability. The partial differential equation of motion governing the lateral vibrations of the pipe is employed to develop the stiffness and inertia matrices corresponding to two of the terms of the equations of motion. The equation of motion further includes a mixed-derivative term that was treated as a source for a dissipative function. The corresponding matrix with this dissipative function was developed and recognized as the potentially destabilizing factor for the lateral vibrations of the fluid carrying pipe. Two types of boundary conditions, namely simply-supported and cantilevered were considered for the pipe. The appropriate mass, stiffness, and dissipative matrices were developed at an elemental level for the fluid carrying pipe. These matrices were then assembled to form the overall mass, stiffness, and dissipative matrices of the entire system. Employing the finite element model developed in this work two series of parametric studies were conducted. First, a pipe with a constant wall thickness of 1 mm was analyzed. Then, the parametric studies were extended to a pipe with variable wall thickness. In this case, the wall thickness of the pipe was modeled to taper down from 2.54 mm to 0.01 mm. This study shows that the critical velocity of a pipe carrying fluid can be increased by a factor of six as the result of tapering the wall thickness.
Author:
Publisher:
ISBN:
Category : Mechanics, Applied
Languages : en
Pages : 384
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Book Description
Author: Donald O. Barnett
Publisher:
ISBN:
Category :
Languages : en
Pages : 65
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Book Description
An analysis is presented of the effect of longitudinal pressure pulsations or vibrations on the velocity distribution in laminar or turbulent fully developed pipe flow. Specifically, the Reynolds equations are formulated in a noninertial reference frame so that the influence of pressure pulsations, vibrations, or a combined pressure and vibrational oscillation can be obtained from a single solution. For axisymmetric developed flow of a constant property (incompressible) fluid, the radial and circumferential momentum equations can be solved and the axial momentum equation is linearized so that the velocity field can be obtained as the sum of a steady and a time-dependent component. By obtaining a solution for the case where the pressure (or amplitude of vibration) varies sinusoidally, one obtains the solution for disturbances of arbitrary waveform through a Fourier series expansion of the disturbance. Results are presented that show that the velocity field is dependent upon the mean flow Reynolds number, a vibrational Reynolds number, and the amplitude of the forcing function. In general, the fluid response to differing waveforms is similar to that obtained for simple harmonic oscillations with respect to the various parameters explored.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
An analysis is presented of the effect of longitudinal pressure pulsations or vibrations on the velocity distribution in laminar or turbulent fully developed pipe flow. Specifically, the Reynolds equations are formulated in a noninertial reference frame so that the influence of pressure pulsations, vibrations, or a combined pressure and vibrational oscillation can be obtained from a single solution. For axisymmetric developed flow of a constant property (incompressible) fluid, the radial and circumferential momentum equations can be solved and the axial momentum equation is linearized so that the velocity field can be obtained as the sum of a steady and a time-dependent component. By obtaining a solution for the case where the pressure (or amplitude of vibration) varies sinusoidally, one obtains the solution for disturbances of arbitrary waveform through a Fourier series expansion of the disturbance. Results are presented that show that the velocity field is dependent upon the mean flow Reynolds number, a vibrational Reynolds number, and the amplitude of the forcing function. In general, the fluid response to differing waveforms is similar to that obtained for simple harmonic oscillations with respect to the various parameters explored.
Author: Patrick Loulou
Publisher:
ISBN:
Category : Finite element method
Languages : en
Pages : 196
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Book Description
Author: M. P. Paidoussis
Publisher:
ISBN:
Category : Aeroelasticity
Languages : en
Pages : 490
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Book Description
Author: Hossein Zanganeh
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
Vortex-induced vibration (VIV) is a fundamental phenomenon commonly encountered in various practical engineering. Owing to the complexities associated with this phenomenon, modelling and prediction of VIV is a challenging task. In this research, a new predictive phenomenological model is developed for VIV of an elastically mounted rigid cylinder subjected to a fluid flow and free to vibrate in both cross-flow (CF) and in-line (IL) directions. The ensuing dynamical system is based on double Duffing-van der Pol (structural-wake) oscillators with the two structural equations containing both cubic and quadratic nonlinear terms. The cubic nonlinearities capture the geometrical coupling of CF/IL displacements excited by hydrodynamic lift/drag forces whereas the quadratic nonlinearities allow the fluid-structure interactions. The model predictions are extensively compared with published and in-house experimental results. Experiments are carried out at the Department's towing tank to calibrate and validate numerical prediction results. Comparisons illustrate the qualitative resemblance between experimental and prediction results, highlighting how the new model can capture several important VIV characteristics including a two-dimensional lock-in, jump and hysteresis phenomenon, and figure-of-eight trajectory tracing the periodically coupled CF/IL oscillations. Moreover, the parametric studies reveal the important effect of geometrical nonlinearities, mass ratio, damping ratio and natural frequency ratio. Insights into hydrodynamic properties such as VIV-induced mean drag, added mass and damping are drawn based on the newly proposed model via analytical-numerical approaches and comparisons with published literature. Consequently, the new prediction model is applied to the VIV analysis of flexible circular cylinders subjected to uniform and linearly sheared currents. To capture a three-dimensional aspect of the flexible cylinder experiencing VIV, nonlinear equations of CF, IL and axial structural oscillations are considered to be coupled with the distributed van der Pol wake-oscillators. Governing equations are numerically solved via a space-time finite difference scheme, and the obtained numerical results highlight several aspects of VIV of elastic cylinders along with the axial motion effects. Apart from the validation of the numerical model with published experimental results, this study reveals how the effect of axial motion and its nonlinear coupling with the two transverse CF/IL motions can be very important. These depend on the reduced velocity, the fluid-structure parameters, the single or multi-mode lock-in condition, and the standing-wave versus travelling-wave features.
