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Dynamic characteristics of heat exchanger tubes vibrating in a tube support plate inactive mode

Description: Tubes in shell-and-tube heat exchangers, including nuclear plant steam generators, derive their support from longitudinally positioned tube support plates (TSPs). Typically there is a clearance between the tube and TSP hole. Depending on design and fabrication tolerances, the tube may or may not contact all of the TSPs. Noncontact results in an inactive TSP which can lead to detrimental flow induced tube vibrations under certain conditions dependent on the resulting tube-TSP interaction dynamics and the fluid excitation forces. The purpose of this study is to investigate the tube-TSP interaction dynamics. Results of an experimental study of damping and natural frequency as functions of tube-TSP diametral clearance and TSP thickness are reported. Calculated values of damping ratio and frequency of a tube vibrating within an inactive TSP are also presented together with a comparison of calculated and experimetnal quantities.
Date: January 1, 1985
Creator: Jendrzejczyk, J.A.
Partner: UNT Libraries Government Documents Department

Dynamic characteristics of heat exchanger tubes vibrating in a tube support plate inactive mode

Description: Tubes in shell-and-tube heat exchangers, including nuclear plant steam generators, derive their support from longitudinally positioned tube support plates (TSPs). Typically there is a clearance between the tube and TSP hole. Depending on design and fabrication tolerances, the tube may or may not contract all of the TSPs. Noncontact results in an inactive TSP which can lead to detrimental flow induced tube vibrations under certain conditions dependent on the resulting tube-TSP interaction dynamics and the fluid excitation forces. The purpose of this study is to investigate the tube-TSP interaction dynamics. Results of an experimental study of damping and natural frequency as functions of tube-TSP diametral clearance and TSP thickness are reported. Calculated values of damping ratio and frequency of a tube vibrating within an inactive TSP are also presented together with a comparison of calculated and experimental quantities.
Date: June 1, 1984
Creator: Jendrzejczyk, J.A.
Partner: UNT Libraries Government Documents Department

Identification of root cause and abatement of vibration of monochromator.

Description: Silicon crystal mirrors are used to reflect high-intensity X-ray beams. A large amount of heat is generated in each mirror. To minimize the effect of thermal expansion on the crystal mirrors, heat is removed by pumping liquid gallium (with a boiling point of 29.8 C) through passages in the crystal mirrors. During system operation, mirror motion should be kept to an acceptable level to avoid performance degradation. There are many potential sources of excitation to the crystal assembly; one such source is the flowing gallium. Two series of tests were performed earlier for a near-prototypical gallium cooling system (1-2). This paper describes a series of tests to measure the general vibration response characteristics of critical components in the monochromator system that contains the mirrors. The main objective of this work is to identify the root cause of vibration and to recommend general guidelines for abatement of vibration. This is achieved by performing many tests to understand the response characteristics under various conditions, by analysis of the response data, and by use of some theoretical considerations.
Date: January 13, 1998
Creator: Jendrzejczyk, J. A.
Partner: UNT Libraries Government Documents Department

Experiment and analysis of instability of tube rows subject to liquid crossflow. [LMFBR]

Description: A tube array subjected to crossflow may become unstable by either one or both of the two basic mechanisms: velocity mechanism and displacement mechanism. The significance of these two mechanisms depends on the mass-damping parameter. The velocity mechanism is dominant for tube arrays with a low mass-damping parameter, and the displacement mechanism is dominant for tube arrays with a high mass-damping parameter. This report presents an experimental and analytical investigation of tube rows in liquid crossflow. The main objective is to verify a mathematical model and the transition between the two mechanisms at the intermediate values of mass-damping parameter. Tests of two tube rows are conducted to determine the critical flow velocity as a function of system damping. Experimental and analytical results are found to be in good agreement.
Date: September 1, 1981
Creator: Chen, S.S. & Jendrzejczyk, J.A.
Partner: UNT Libraries Government Documents Department

Fluid forces on two circular cylinders in crossflow

Description: Fluid excitation forces are measured in a water loop for two circular cylinders arranged in tandem and normal to flow. The Strouhal number and fluctuating drag and lift coefficients for both cylinders are presented for various spacings and incoming flow conditions. The results show the effects of Reynolds number, pitch ratio, and upstream turbulence on the fluid excitation forces.
Date: January 1, 1986
Creator: Jendrzejczyk, J.A. & Chen, S.S.
Partner: UNT Libraries Government Documents Department

Fluid forces on two circular cylinders in crossflow

Description: Fluid excitation forces are measured in a water loop for two circular cylinders arranged in tandem and normal to flow. The Strouhal number and fluctuating drag and lift coefficients for both cylinders are presented for various spacings and incoming flow conditions. Results show the effects of Reynolds number, pitch ratio, and upstream turbulence on the fluid excitation forces.
Date: June 1, 1985
Creator: Jendrzejczyk, J.A. & Chen, S.S.
Partner: UNT Libraries Government Documents Department

Instability characteristics of fluidelastic instability of tube rows in crossflow

Description: An experimental study is reported to investigate the jump phenomenon in critical flow velocities for tube rows with different pitch-to-diameter ratios and the excited and intrinsic instabilities for a tube row with a pitch-to-diameter ratio of 1.75. The experimental data provide additional insights into the instability phenomena of tube arrays in crossflow. 9 refs., 10 figs.
Date: April 1, 1986
Creator: Chen, S.S. & Jendrzejczyk, J.A.
Partner: UNT Libraries Government Documents Department

Hydroelastic response of a circular tube in eccentric annular flows

Description: This paper presents the experimental study of the hydroelastic response of a tube located concentrically and eccentrically in a circular water-flow channel. Acceleration components in two orthogonal directions are measured at the midpoint of the test element using a pair of accelerometers. The investigation includes determination of natural frequencies, damping factors, rms displacements, and the variations of the above dynamic quantities with eccentricity and mean axial-flow velocity. The experimental data is processed into statistical forms, including power spectral density function and root-mean-square values. The results show that the natural frequency of the tube shifts as the eccentricity or flow velocity increases, that the damping in flowing water is greater than that in stationary water and increases with increasing flow velocity and eccentricity, and that the rms displacement increases as the eccentricity and/or flow velocity increases.
Date: January 1, 1983
Creator: Lin, W.H. & Jendrzejczyk, J.A.
Partner: UNT Libraries Government Documents Department

Flow-induced vibration of a curved tube array subject to liquid cross flow

Description: This paper presents the results of tests of a curved-tube array in air, in stationary water, and in flowing fluid. A curved-tube array can be subjected to fluidelastic instability which is similar to that in a straight-tube array. However, in a curved-tube array, tube natural frequencies are different in two directions and there are frequency variations among different tube rows; the critical-flow velocity and instability mode are not the same as those of the corresponding straight-tube array. Based on the experimental data, a mathematical consideration, it can be concluded that some of the instability modes will not occur in a curved-tube array; therefore, the critical-flow velocity established for straight-tube arrays can be considered as a conservative estimate for a corresponding curved-tube array.
Date: January 1, 1981
Creator: Jendrzejczyk, J.A. & Chen, S.S.
Partner: UNT Libraries Government Documents Department

Stability of tube rows in crossflow. [LMFBR]

Description: A mathematical model for the instability of tube rows subjected to crossflow is examined. The theoretical model, based on the fluid-force data for a pitch-to-diameter ratio of 1.33, provides additional insight into the instability phenomenon. Tests are also conducted for three sets of tube rows. The effects of mass ratio, tube pitch, damping, detuning and finned tubes are investigated. Theoretical results and experimental data are in good agreement.
Date: October 1, 1982
Creator: Chen, S.S. & Jendrzejczyk, J.A.
Partner: UNT Libraries Government Documents Department

Dynamic responses of heat exchanger tube banks. [LMFBR]

Description: Understanding and modeling fluid/structure interaction in cylinder bundles is a basic requirement in the development of analytical methods and guidelines for designing LMFBR heat exchanger and reactor fuel assemblies that are free from component vibration problems. As a step toward satisfying this requirement, an analytical and experimental study of tube banks vibrating in liquids is presented. A general method of analysis is presented for free and forced vibrations of tube banks including tube/fluid interaction, and numerical results are given for tube banks subjected to various types of excitations. Two cantilevered tubes were tested in a water tank, and the natural frequencies and forced responses of coupled motion were measured. Experimental data and analytical results are in reasonably good agreement. The analytical method presented is currently being extended to account for the flowing fluid in tube banks and will be used in the development of the mathematical models for crossflow- and parallel-flow-induced vibrations of tube bundles. Those models will be useful in predicting the response of tube bundles and in design to avoid detrimental vibration.
Date: April 1, 1976
Creator: Chen, S. S. & Jendrzejczyk, J. A.
Partner: UNT Libraries Government Documents Department

Surface measurements of shear wave velocity at the 7-GeV APS site

Description: A knowledge of shear wave speeds as a function of site location and soil depth is fundamental co the vibration study of the 7-GeV Experiment Hall foundation supporting the storage ring magnets, insertion devices, and experiments. Among other things, knowledge of the shear wave speed allows one to calculate the shear modulus of elasticity of the soil using the relationship G pV{sup 2}{sub S} where G is shear modulus of elasticity, p is soil density, and V{sub s} is shear wave speed. The shear modulus, in turn, is one of the most important parameters in performing a dynamic analysis of the response of the foundation to both external excitation (ground motion) and excitation sources internal to the Experiment Hall.
Date: December 1, 1987
Creator: Jendrzejczyk, J.A. & Wambsganss, M.W.
Partner: UNT Libraries Government Documents Department

Vibro-impact responses of a tube with tube--baffle interaction. [LMFBR]

Description: The relatively small, inherent tube-to-baffle hole clearances associated with manufacturing tolerances in heat exchangers affect the vibrational characteristics and the response of the tube. Numerical studies were made to predict the vibro-impact response of a tube with tube-baffle interaction. The finite element method has been employed with a non-linear elastic contact spring-dashpot to model the effect of the relative approach between the tube and the baffle plate. The coupled equations of motion are directly integrated with a proportional system damping represented by a linear combination of mass and stiffness. Lumped mass approach with explicit time integration scheme was found to be a suitable choice for tube-baffle impacting analysis. Fourier analyses indicate that the higher mode contributions to the tube response are significant for strong tube-baffle impacting. The contact damping forces are negligible compared with the contact spring forces. The numerical analysis results are in reasonably good agreement with those of the experiments.
Date: January 1, 1978
Creator: Shin, Y.S.; Sass, D.E. & Jendrzejczyk, J.A.
Partner: UNT Libraries Government Documents Department

Dynamics of tubes in fluid with tube-baffle interaction

Description: Three series of tests are performed to evaluate the effects of tube to tube-support-plate (TSP) clearance on tube dynamic characteristics and instability phenomena for tube arrays in crossflow. Test results show that, for relatively large clearances, tubes may possess TSP-inactive modes in which the tubes rattle inside some of the tube-support-plate holes, and that the natural frequencies of TSP-inactive modes are lower than those of TSP-active modes, in which the support plates provide knife-edge type support. Tube response characteristics associated with TSP-inactive modes are sensitive to tube-to-TSP clearance, TSP thickness, excitation amplitude, tube alignment, and the fluid inside the clearance. In addition, tube response is intrinsically nonlinear, with the dominance of TSP-inactive or TSP-active modes depending on the magnitudes of different system parameters. In general, such a system is difficult to model; only a full-scale test can provide all the necessary characteristics. A tube array supported by TSPs with relatively large clearances may be subjected to dynamic instability in some of the TSP-inactive modes; tube response characteristics and impact forces on TSPs for a tube row are studied in detail in this report. Tube displacements associated with the instability of a TSP-inactive mode are small; however, impacts of the tube against TSPs may result in significant damage in a relatively short time. 52 figures.
Date: September 1, 1983
Creator: Chen, S.S.; Jendrzejczyk, J.A. & Wambsganss, M.W.
Partner: UNT Libraries Government Documents Department

Effect of tube-support interaction on the dynamic responses of heat exchanger tubes. [LMFBR]

Description: Operating heat exchangers have experienced tube damages due to excessive flow-induced vibration. The relatively small inherent tube-to-baffle hole clearances associated with manufacturing tolerances in heat exchangers affect the tube vibrational characteristics. In attempting a theoretical analysis, questions arise as to the effects of tube-baffle impacting on dynamic responses. Experiments were performed to determine the effects of tube-baffle impacting in vertical/horizontal tube orientation, and in air/water medium on the vibrational characteristics (resonant frequencies, mode shapes, and damping) and displacement response amplitudes of a seven-span tube model. The tube and support conditions were prototypic, and overall length approximately one-third that of a straight tube segment of the steam generator designed for the CRBR. The test results were compared with the analytical results based on the multispan beam with ''knife-edge'' supports.
Date: January 1, 1977
Creator: Shin, Y.S.; Jendrzejczyk, J.A. & Wambsganss, M.W.
Partner: UNT Libraries Government Documents Department

Stability of Tube Rows in Crossflow

Description: A mathematical model for the instability of tube rows subjected to crossflow is examined. The theoretical model, based on the fluid-force data for a pitch-to-diameter ratio of 1.33, provides additional insight into the instability phenomenon. Tests are also conducted for three sets of tube rows. The effects of mass ratio, tube pitch, damping, detuning and finned tubes are investigated. Theoretical results and experimental data are in good agreement.
Date: October 1982
Creator: Chen, S. S. & Jendrzejczyk, J. A.
Partner: UNT Libraries Government Documents Department

Experiments on Tubes Conveying Fluid

Description: Tests are conducted for tubes conveying fluid for six types of support conditions. The objectives are to understand the dynamic characteristics of such systems for different support conditions and to explore the methods to control tube stability. Transition from one instability mechanism to another is examined, and the feasibility of using feedback control to increase the critical flow velocity is demonstrated.
Date: February 1983
Creator: Jendrzejczyk, J. A. & Chen, S. S.
Partner: UNT Libraries Government Documents Department

Effect of tube-support interaction on the vibration of a tube on multiple supports

Description: The effects of tube orientation (horizontal/vertical), tube/support misalignment, fluid medium (air/water), tube/support-hole clearance, support thickness, exciting force amplitude, and support spacing on the vibrational characteristics (resonant frequencies, mode shapes, and damping) and displacement response amplitude of a multi-span tube were determined from thirteen different tests. The test model features a 15.875 mm (0.625 in.) dia x 3.175 mm (0.125 in.) thick x 5.232 m (206 in.) long seamless Croloy (2-/sup 1///sub 4/% Cr--1% Mo) tube, and combinations of four support thicknesses (12.70 mm (/sup 1///sub 2/ in.), 19.05 mm (/sup 3///sub 4/ in.), 38.10 mm (1/sup 1///sub 2/ in.), and 50.80 mm (2 in.)) and three sizes of diametral clearance of tube/support-hole (0.254 mm (10 mils), 0.508 mm (20 mils), and 0.762 mm (30 mils)). The test results were compared with the analytical results based on the multi-span beam with ''knife-edge'' supports.
Date: January 1, 1977
Creator: Shin, Y. S.; Jendrzejczyk, J. A. & Wambsganss, M. W.
Partner: UNT Libraries Government Documents Department

Experiments on fluidelastic vibrations of tube arrays

Description: The overall objective of the activity is to develop new and/or improved, experimentally-validated analytical methods and guidelines for designing LMFBR components to avoid detrimental flow induced vibration. Many reactor system components, such as heat exchanger tubes and reactor fuel pins are susceptible to flow induced vibration. Due to fluid coupling, the tubes will respond in one or several of coupled modes. Therefore, understanding the coupled modes is essential in design to avoid detrimental flow-induced vibrations. Four series of tube arrays are tested. The arrangements of the tubes are as follows: (a) a row of five tubes with the gap to tube radius ratio (G/R) equal to 2.0, 1.0, and 0.25; (b) three-tube arrays in the staggered arrangement with G/R equal to 2.0, 1.0 and 0.5; (c) seven-tube arrays in the staggered arrangement with G/R equal to 1.5, 1.0 and 0.4; and (d) four-tube array in a square pattern with G/R = 0.5. The fourth series is tested under five different conditions: (1) fully submerged in unconfined water; (2) partially submerged in water; (3) near a flat wall; (4) contained in a circular cylinder; and (5) fully submerged in a liquid of high viscosity (mineral oil). A means to excite the tubes is provided by an electromagnetic exciter assembly. A servo system can be used to control input. Response in the form of tube acceleration is measured using two accelerometers mounted on each tube. The data is processed in a fast Fourier Transform Analyzer. An analysis is made for each test case. The detailed information for uncoupled and coupled natural frequencies, mode shapes, damping, and tube response are presented in the report. The experimental data and analytical results are found to be in good agreement.
Date: April 1, 1977
Creator: Chen, S. S.; Jendrzejczyk, J. A. & Wambsganss, M. W.
Partner: UNT Libraries Government Documents Department

Vibration considerations in the design of the Advanced Photon Source at Argonne National Laboratory

Description: The Advanced Photon Source (APS), a new synchrotron radiation facility being built at Argonne National Laboratory, will provide the world's most brilliant X-ray beams for research in a wide range of technical fields. Successful operation of the APS requires an extremely stable positron closed orbit. Vibration of the storage ring quadrupole magnets, even in the submicron range, can lead to distortion of the positron closed orbit and to potentially unacceptable beam emittance growth, which results in degraded performance. This paper presents an overview of the technical approach used to minimize vibration response, beginning at the conceptual stage, through design and construction, and on to successful operation. Acceptance criteria relating to maximum allowable quadrupole magnet vibration are discussed. Soil properties are used to determine resonant frequencies of foundations and to predict attenuation characteristics. Two sources are considered to have the potential to excite the foundation: far-field sources, which are produced external to the facility, and near-field sources, which are produced within the facility. Measurements of ambient ground motion, monitored to determine far- field excitation, are presented. Ambient vibration was measured at several operating facilities within Argonne to gain insight on typical near-field excitation sources. Discussion covers the dynamic response characteristics of a prototypic magnet support structure to various excitations, including ambient floor motion, coolant flow, and magnet power. 19 refs., 10 figs., 5 tabs.
Date: January 1, 1991
Creator: Jendrzejczyk, J.A. & Wambsganss, M.W.
Partner: UNT Libraries Government Documents Department

Ambient ground motion measurements at Argonne National Laboratory over extended time periods

Description: Successful operation of the APS facility requires a very stable particle beam. Vibration coupled through mechanical systems, such as magnet supports, beam tube supports, and other paths can cause deterioration of the particle beam. There are two sources of vibration: external, or far field, which is generated external to the APS site and internal, or near field, which is generated on site and associated with operation of the facility. Internal vibration sources can be controlled or minimized using good design practices to eliminate or reduce vibration amplitudes of machinery and equipment. Depending on their origin, external vibration sources may or may not be controllable, therefore it is necessary to have sufficient knowledge of their amplitude level and frequency content to predict any adverse effects on the operation of the APS facility.
Date: March 1, 1988
Creator: Jendrzejczyk, J.A.; Wambsganss, M.W. & Smith, R.K.
Partner: UNT Libraries Government Documents Department

Ambient ground motion at the 7 GeV site at Argonne National Laboratory over extended time periods

Description: Successful operation of the APS facility requires a very stable particle beam. Vibration coupled through mechanical systems, such as magnet supports, beam tube supports, and other paths can cause deterioration of the particle beam. There are two sources of vibration: external, or far field, which is generated external to the APS site and internal, or near field, which is generated on site and associated with operation of the facility. Internal vibration sources can be controlled or minimized using good design practices to eliminate or reduce vibration amplitudes of machinery and equipment. Depending on their origin, external vibration sources may or may not be controllable, therefore it is necessary to have sufficient knowledge of their amplitude level and frequency content to predict any adverse effects on the operation of the APS facility. The primary objective of this study was to measure the far field ground vibration at the 7 GeV site over long time periods to get an accurate representation of its frequency and amplitude characteristics.
Date: December 1, 1988
Creator: Jendrzejczyk, J.A.; Nagy, Z. & Smith, R.K.
Partner: UNT Libraries Government Documents Department