bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Singular Nature of Rotating Circular Rings With Symmetry
Authors: Quinn D. Dane , Clemons Curtis B. , Dempsey Kevin M. 
Published: March 2022

Abstract
We study the S𝒪(2) symmetric deformation of circular rings. The equations of motion are based on general partial differential equations governing the elastodynamics of geometrically exact rings, which have been formulated by Dempsey [2], based on the work of Libai and Simmonds [6]. Thus, the formulation is valid for arbitrary pressure forcing, large deformations, and finite strains, although the results are tempered by a linear constitutive relation and an assumption of plane strain.
With the assumption that the deformation retains S𝒪(2) symmetry, the partial differential equations are reduced to a set of coupled ordinary differential equations. Within this restricted space of solutions, we study the existence and stability of relative equilibria and discuss the effects of constant hydrostatic pressure on the dynamical response. Specifically, we find that interaction between inertial effects arising from rotational motion and the combined elastic and external pressure forces can produce unexpected behavior, including the existence of a “buckled” state which retains the symmetry, yet physically implies that material planes do not lie in the radial direction. Such a state is shown to effect the large-amplitude response of the system in a singular limit of the governing equations.
Dynamic Response of a Rod due to Vortex-Induced Vibration
Authors: Massih A. R. , Forsberg K. 
Published: March 2022

Abstract
The dynamic response of a circular cylinder subject to cross-flows is analyzed using the wake oscillator model of Iwan and Blevins. The nonlinear differential equations for the system is solved by an approximate algebraic method and the results are compared against full numerical solutions with excellent concordance. Also we have compared the predictions of tube displacements and vortex frequencies with available experimental data. Finally, the computational fluid dynamics code ADINA-F and the structural mechanics code ADINA are used concurrently to study the dynamic behavior of the system.
Aerodynamic Noise Calculation of a Detaching Flow
Authors: Huang S. , Béguier C. 
Published: March 2022

Abstract
A numerical study based on the macro-simulation method is carried out in order to determine the aerodynamical noise of a turbulent detaching flow. The macro-simulation method uses a Large Eddy Simulation (LES) code to obtain at the same time, the large structures of the flow and the small structures modelled by a sub-grid eddy viscosity, and an acoustic code able to calculate, in the far field, the radiated aerodynamical noises, from the Lighthill-Curle formalism. The method permits to dissociate the different aerodynamical noises: the wall noise, due to the wall-pressure fluctuations, the shear noise, due to the large scale quadrupole sources, and the turbulence self noise, generated by the small scale quadrupole sources. The case of the normal backward facing step is presented, for which the different emitted noises are analysed and compared together. Some theoretical hypotheses are also tested.
Wall-Pressure Fluctuations Under a Three-Dimensional Boundary Layer
Authors: Panton Ronald L. 
Published: March 2022

Abstract
This paper gives a simple model of the pressure spectrum in wavenumber-phase velocity space for three-dimensional boundary layers. Equally as important is the definition proposed for a vector convection velocity and the method proposed for conversion of wavenumber-frequency variables into wavenumber-phase velocity variables. In three-dimensional flows one must define a phase speed that is a vector c = (c1, C3). A complete vector wave speed cannot be determined from pressure data, however, the component ck in the direction of k, ck ≡ Ω/k, can be defined and is found to be sufficient. Here k is the wave vector magnitude and α its direction. This allows the spectrum function to be well represented in the polar form Φ(k, α, ck). Moreover, for given k, a convection velocity may be defined as the point of maximum Φ(k, α, ck). Convection velocity is expressed in the form of a magnitude ck_max(k) and direction αmax(k). The three-dimensional spectrum model was produced as a generalization of Witting’s two-dimensional model. By splitting the boundary layer into two parts, the simplest generalization is formulated. Each part has its own transport velocity vector. Sample calculations are displayed as contour plots of Φ (ck, α) for fixed wavenumber k. On such plots the maximum is the convection velocity. The plots reveal an abrupt transition in the spectrum as the wavenumber increases; a result of the two layer assumption.
The Flow Dynamics of an Asymmetrical Circular Cylinder Under Acoustic Excitation
Authors: Lo K. W. , Ko N. W. M. 
Published: March 2022

Abstract
In the present study, the asymmetry of the cylinder was achieved by attaching a 90° V-grooved strip on the cylinder surface. Different flow regimes are present on the grooved and smooth halves. Under acoustic excitation, the flow regimes over the two halves are changed and the near wake structures of the grooved cylinder are modified. Further, the transition process is not stationary in time and two different transient processes are observed during the transition.
Stability of a Horizontally Rotating Fluid-Tube Cantilever
Authors: Panussis Dimitrios A. , Dimarogonas Andrew D. 
Published: March 2022

Abstract
The case of simultaneous in-plane and out-of-plane lateral vibrations of small amplitude of a horizontally rotating cantilever tube conveying fluid is examined. The rotation is with respect to the fixed end of the tube at a constant angular velocity. The diameter of the tube is constant and much smaller than its length. There is no nozzle attached at the free end. The tube is inextensible. Two inter-dependent partial differential equations in the two directions of deflection of the system are derived by means of the equilibrium of forces on a fluid-tube element. The same system of equations is derived by means of Hamilton’s principle. An approximate solution is sought in the case of linearized out-of-plane lateral vibrations in the form of a series of normalized eigenfunctions from the linear cantilever beam theory using Galerkin’s method. The threshold of instability, namely the critical dimensionless circular frequency and speed of flow at the onset of instability of the fluid-tube cantilever are investigated. The numerical results show that the externally applied constant rotational speed increases the critical circular frequency and speed of flow compared to the non-rotating fluid-tube cantilever, thus, increasing the stiffness of the system.
Theoretical Instability Analysis of a Rotating Flexible Disk Subjected to Swirling Fluid Flow
Authors: Watanabe Masahiro , Hara Fumio 
Published: March 2022

Abstract
This paper deals with a theoretical instability analysis of a rotating flexible disk subjected to swirling fluid flow, resulting in the generation of a strong coupling between the flexible disk vibration and swirling fluid flow around it, and a possible mechanism governing unstable vibration. In the instability analysis, the basic equations of swirling fluid flow around the rotating disk are based on Navier-Stokes equations integrated over the gap width between the rotating disk surface and the shroud wall. The structural vibration equation of the rotating flexible disk is based on the Kirchhoff-Love plate model. The equations of coupled fluid-structure motion take into account the moving boundary conditions with respect to both the rotating disk and the fluid flow. These equations are linearized for small deflection of the disk near the equilibrium state, and the solution of these equations is obtained using the multimodal expansion approximation and applying the Galerkin method. The theoretical results show a good agreement to the experiment with respect to the unstable vibration mode shapes and dependence of the instability frequency on the rotating speed, but only a qualitative agreement for the critical speed at which the disk’s unstable vibration occurs.
A Friction-Based Model for Fluidelastic Forces Induced by Axial Flow
Authors: Porcher G. , de Langre E. 
Published: March 2022

Abstract
Self excitations of slender structures under axial flow have been reported in a large variety of local flow configurations. This paper reports on the analytical results of a research program aimed at studying basic phenomena leading to fluidelastic instabilities.
A friction-based model is proposed to calculate the fluidelastic forces induced by axial flow. It is developed here for an axial flow between two surfaces. This method is an extension of the studies which were carried out by Miller (1970), Hobson (1982) and Mulcahy (1988). A pressure drop is introduced in the system with a local or continuous pressure drop factor. This model is based on a modal analysis and is presented for structures with several degrees-of-freedom.
The continuity and momentum equations are integrated along the fluid domain thickness with the boundary conditions on the structure. A linearization of these equations gives the expression of the fluctuating velocity and pressure. With a modal analysis, the fluidelastic force expression is obtained by the integration of the pressure on the structure wall. Three terms, called added terms, are identified: inertial, damping and stiffness. For several cases and different locations of the pressure drop, the behavior of this system and the flutter instability are analysed.
Hydroelastic Vibration of Free-Edge Annular Plates
Authors: Kwak Moon K. , Amabili Marco 
Published: March 2022

Abstract
This paper is concerned with the virtual mass effect due to the presence of water on the natural frequencies of free-edge annular plates resting on free surface, which has never been studied theoretically. Recently, experiments were carried out for free-edge annular plates to find the so-called non-dimensionalized added virtual mass incremental factors. In this paper, theoretical non-dimensional added virtual mass incremental factors are obtained by employing the Hankel transformation technique in conjunction with the Fourier-Bessel series approach. It is found that the theoretical non-dimensionalized added virtual mass incremental factors for free-edge annular plates resting on free-surface agree well with experimental ones.
Fluid-Damping-Controlled Instability of Tubes in Crossflow
Authors: Chen S. S. , Cai Y. , Srikantiah G. S. 
Published: March 2022

Abstract
Motion-dependent fluid forces are measured in a water channel. From the measured fluid forces, fluid-stiffness and fluid-damping coefficients are calculated as a function of reduced flow velocity, oscillation amplitude, and Reynolds number. Once these coefficients are known, the mathematical model based on the unsteady-flow theory can be applied to predict structural instability due to fluid damping. The cases we considered are a single tube, twin tubes, tube row, triangular array, and square arrays. The results show instability regions that are based on the fluid-damping coefficients and provide answers to a series of questions on fluidelastic instability of tube arrays in crossflow.
A Fluidelastic Instability Model With an Extension to Full Flexible Multi-Span Tube Arrays
Authors: Li Ming , Weaver David S. 
Published: March 2022

Abstract
An analytical model was developed for the prediction of fluidelastic instability in cross flow multi-span heat exchanger tube arrays. The model is based on concepts developed by Lever and Weaver, as well as Yetisir and Weaver, but is modified and extended to include other important factors. Rather than the nonlinear function previously used, a linear area perturbation decay function is introduced to account for the decay of disturbances away from an oscillating tube. Thus, an analytical solution can be obtained. Flexible tubes directly two rows upstream and downstream of a central tube, neglected in the earlier work, are included in the present model. Improved agreement with experimental data is obtained for parallel triangular tube arrays. In contrast, little improvement is achieved for the other tube patterns due to the reduced influence of the upstream tube wake. The velocity distribution and mode shape along the tube span are also introduced into the model. This is made possible because of the explicit stability equation. Therefore, the present model can be used to calculate the fluidelastic instability for the multi-span tube arrays. Comparison between theory and experimental data shows good agreement.
Experimental and Computational Investigation Into Vibration Wear of Control Rods in French PWRs
Authors: Borsoi Laurent , Canteneur Christian , Barbe Gérard 
Published: March 2022

Abstract
The under-card wear of control rods due to flow-induced vibration was discovered in 1986. To cope with this phenomenon, Framatome at once erected the full-scale Magaly test facility, in operation since 1988. Then in 1991 Framatome initiated exploratory numerical simulations using the Nat03 structural code specifically developed for this purpose. After introducing Magaly and Nat03, this paper illustrates how the following ill-posed inverse-problem has been attacked: from rod vibration measured with Magaly, how to calibrate via Nat03 computation a rustic model of the rod excitation created by the main flow coming from the fuel assembly. A single force applied on the control rod just beyond the continuous guidance section is sufficient to “support” after adjustment all the available experiment-computation comparisons: rod displacement (trajectory, standard deviation, PSD), contact force (average value, contact duration), and wear work rate, for three control rods differently located in the cards and nine card elevations with different flow rates.
Prediction of Tube Wear due to Flow-Induced Vibration in PWR Steam Generators
Authors: Rao M. S. M. , Laskowski L. J. , Srikantiah G. S. , Ahluwalia K. S. 
Published: March 2022

Abstract
Tube wear due to flow-induced vibration has been of continuing concern in operating Pressurized Water Reactor steam generators. Tube plugging or repair is necessary when inservice inspection indicates tube wall thickness less than a minimum acceptable value. Additional considerations involve the use of tube stabilizers or motion limiters when a plugged vibrating tube can impact on its neighboring active tubes. An analytical wear assessment methodology that predicts tube wear caused by flow-induced vibration is described. The methodology is based on determining a set of wear parameters from a non-linear finite element simulation of the steam generator tubes incorporating clearances at the tube supports under flow-induced turbulence and fluidelastic excitation. Tube wear progression during steam generator life is projected from the analytically determined parameters and experimental wear correlations. The methodology is applied to predict tube wear at scheduled inspections in a steam generator.
Improved Estimation of Fluidelastic Instability Threshold for Tube Arrays in Two-Phase Flow: A Model Incorporating Temporal Fluid Force Correlation Along the Tube Axis
Authors: Nakamura T. , Chen S. S. , Mureithi N. W. , Kusakabe T. 
Published: March 2022

Abstract
The unsteady flow model for the prediction of fluidelastic instability in tube arrays has been employed successfully to single phase cross-flow. Stability boundaries as well as inter-tube vibration mode patterns can be predicted.
Single phase flow studies are a precursor to the ultimate practical problem of fluidelastic instability in heat exchangers where the flow consists of two co-existing phases. In principle, existing unsteady fluid force models can be applied to two-phase flow induced vibration. However, the models become intractably complex for the case of U-bend tubes in two-phase flow. In single phase flow, the fluid forces may be considered to be fully correlated along the tube span. This is not the case for two-phase flow. For tube lengths much longer than the typical linear dimension of the two phase flow unit structure (slug, bubble etc.), forces along the tube span are only partially correlated.
In this paper, an unsteady flow model taking into account partial spanwise correlation is presented. The model is applied to fluidelastic analysis of a long span heat exchanger tube. Preliminary results show that the effect of partial correlation is to reduce the effective net fluid forces which thus raises the effective instability threshold. Another important result is the introduction of additional coupling between modes that would otherwise be uncoupled in the fully correlated case. This has important implications for heat exchanger tubes which have closely spaced modes.
Damping of Heat Exchanger Tubes in Two-Phase Flow
Authors: Pettigrew Michel J. , Taylor Colette E. 
Published: March 2022

Abstract
Two-phase flow exists in many shell-and-tube heat exchangers such as condensers, evaporators and nuclear steam generators. Some knowledge on tube damping mechanisms is required to avoid flow-induced vibration problems.
This paper outlines the development of a semi-empirical model to formulate damping of heat exchanger tube bundles in two-phase cross-flow. The formulation is based on information available in the literature and on the results of recently completed experiments. The effects of several parameters such as flow velocity, void fraction, confinement, flow regime and fluid properties are discussed. These parameters are taken into consideration in the formulation of a practical design guideline.
Modelling of the Seal Flow Between an Impeller Shroud and the Static Housing With an ALE Method: Comparison Between Calculated and Measured Dynamic Coefficients
Authors: Undreiner S. , Frei A. 
Published: March 2022

Abstract
The leakage flow between the shroud-pump impeller and its housing is simulated with a Navier-Stokes solver. The fluid-structure interactions are modelled with an Arbitrary Lagrangian Eulerian method (ALE). The force components and the rotordynamic coefficients obtained from the numerical simulation are compared to those calculated from measurement. The Navier-Stokes solver is a finite element code, N3S, developed by “Electricité de France”. It solves the Reynolds-averaged Navier-Stokes equations, with a standard k-ε model. The ALE method consists in a calculation of a mesh velocity. A first order approximation provides equations similar to the standard Navier-Stokes equations. Sulzer-pumps has performed measurements. The test installation consists of a test rig, a closed loop with the required components for pressure, temperature, and flow control, and a data acquisition and handling system. This test rig allows the identification of the rotordynamic coefficients of pump rotor components like impeller and annular seals. The dynamic coefficients comparison shows a good prediction of the numerical model, except for the stiffness coefficients. Other functionning conditions have to be tested before to conclude on the ALE model abilities. Although the requiered CPU time to reach the convergence is long, this type of model can be very interesting in the future for such a complicated 3D flow.
Transverse Vibrations of Fluid Filled Bellows Expansion Joints
Authors: Jakubauskas V. , Weaver D. S. 
Published: March 2022

Abstract
A theoretical model is developed for the transverse vibrations of bellows expansion joints. The model is based on Timoshenko beam theory and includes the added mass effect of an internal fluid. An analytical expression for bellows natural frequencies is developed in the form of a Rayleigh quotient and is presented in a way which is suitable for hand calculations. The results for the first four transverse modes are compared with experiments as well as the predictions of the simplified analysis of the Expansion Joint Manufacturers Association (EJMA). While the present analysis agrees well with experiments, the EJMA approach can be substantially in error due to its neglect of rotary inertia and the convolution distortion component of fluid added mass.
An Investigation of Flow-Induced Multiple-Mode Vibrations of Gates
Authors: Billeter Peter , Staubli Thomas , Volkart Peter 
Published: March 2022

Abstract
An experimental investigation of flow-induced vibrations of gates with multiple degrees-of-freedom will be presented: An underflown vertical gate plate was allowed to oscillate both in the cross-flow (z-) and in the streamwise (x-) direction. The two purposes of the investigation were to further the insight into the hydrodynamic coupling mechanisms of the two vibration modes and to determine the interaction of the unsteady lift and drag forces. Self-excited vibration tests were run with reduced velocities Vrz and Vrx from 0.8 to 14 covering a range in which the instability-induced excitation (IIE) due to impinging-leading-edge-vortices (ILEV) as well as the transition to galloping (MIE) occurred. The ratio of the natural frequencies of the two vibration modes fx0/fz0, the gate opening ratio s/d, and the submergence of the gate plate were varied. Depending on the ranges of reduced velocities and frequency ratios, a complex interaction of two different kind of instability induced excitation was detected. Furthermore, it was found that streamwise IIE-excitation and cross-flow galloping coexist simultaneously. To assess the relevant fluid dynamic amplification and attenuation mechanisms, simultaneous body response and flow velocity measurements were carried out.
Systems Analysis of Launch Vehicle Aeroelastic Coupling
Authors: Dotson K. W. , Baker R. L. , Bywater R. J. 
Published: March 2022

Abstract
Forces due to alternating flow states on the payload fairing of launch vehicles can couple with structural responses during transonic flight. A new methodology for the assessment of this type of self-sustained oscillation is applied for an actual launch vehicle mission. Corresponding internal launch vehicle loads are compared with those for the other transonic airloads events. The limit cycle amplitude from the analysis is compared with that from application of an existing technique in the literature. It is shown that the new methodology can be significantly less conservative than the stability criterion for bounded system responses. The historical assumption that the alternating flow forces on the payload fairing couple with a single launch vehicle bending mode is investigated through transient analysis of the fully coupled system. Evidence of alternating flow separation in flight data for the Titan IV launch vehicle is presented.