Prediction of Flow-Induced Vibrations in Tubular Heat Exchangers—Part I: Numerical Modeling vibrations due to crossflow in the shell side of heat exchangers pose a
01 Jan 2009-
TL;DR: In this article, a finite element approach is used to model the interaction between tubes in a bundle of finite tube elements, where the interaction is represented by fluidelastic coupling forces, which are defined in terms of the multidegree-of-freedom elastodynamic behavior of each tube in the bundle.
Abstract: problem of major interest to researchers and practicing engineers. Tube array vibrations may lead to tube failure due to fretting wear and fatigue. Such failures have resulted in numerous plant shutdowns, which are often very costly. The need for accurate prediction of vibration and wear of heat exchangers in service has placed greater emphasis on the improved modeling of the associated phenomenon of flow-induced vibrations. In this study, the elastodynamic model of the tube array is modeled using the finite element approach, wherein each tube is modeled by a set of finite tube elements. The interaction between tubes in the bundle is represented by fluidelastic coupling forces, which are defined in terms of the multidegree-of-freedom elastodynamic behavior of each tube in the bundle. Explicit expressions of the finite element coefficient matrices are derived. The model admits experimentally identified fluidelastic force coefficients to establish the final form of equations of motion. The nonlinear complex eigenvalue problem is formulated and solved to determine the onset of fluidelastic instability for a given set of operating parameters. DOI: 10.1115/1.3006950
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TL;DR: In this article, the vibration acceleration signals of a brittle graphite heat transfer tube were measured by means of accelerometer sensors and datum acquisition systems at varied steam pressure, solid holdup, particle diameter and axial position to investigate the vibration characteristics of the tube induced by an internal vapor-liquid-solid boiling flow.
19 citations
TL;DR: In this paper, a straight graphite tube with an internal vapor-liquid-solid flow was derived and discussed for vibration analysis when the tube was fixed at both ends, and a model of mixed phase flow was used to deal with fluid parameters.
11 citations
TL;DR: In this article, a semi-analytical model was developed to predict the onset of flow-induced vibrations in two configurations of tube bundles, and results were examined in the light of Tubular Exchange Manufacturers Association (TEMA) predictions.
Abstract: It has become evident that the modeling of the complex dynamics of fluidelastic forces that give rise to vibrations of tube bundles requires a great deal of experimental insight. Accordingly, the prediction of the flow-induced vibration due to unsteady cross-flow can be greatly aided by semi-analytical models, in which some coefficients are determined experimentally. A laboratory test rig with an instrumented test bundle is constructed to measure the fluidelastic coefficients to be used in conjunction with the mathematical model derived in Part I of this paper. The test rig admits two different test bundles, namely, the inline-square and 45 deg rotated-square tube arrays. Measurements were conducted to identify the flow-induced dynamic coefficients. The developed scheme was utilized in predicting the onset of flow-induced vibrations in two configurations of tube bundles, and results were examined in the light of Tubular Exchange Manufacturers Association (TEMA) predictions. The comparison demonstrated that TEMA guidelines are more conservative in the two configurations considered.
10 citations
03 May 2010
TL;DR: In this paper, the authors proposed a finite element approach to model the interaction between tubes in the bundle, which is represented by fluidelastic coupling forces, defined in terms of the multi-degree-of-freedom elastodynamic behavior of each tube.
Abstract: The need for accurate prediction of vibration and wear of heat exchangers in service has placed greater emphasis on improved modeling of the associated phenomenon of flow-induced vibrations. It was recognized that modeling of the complex dynamics of fluidelastic forces, that give rise to vibrations of tube bundles, requires a great deal of experimental insight. Accordingly, the prediction of the flow-induced vibration due to unsteady cross-flow can be greatly aided by semi-analytical models, in which some coefficients are determined experimentally. In this paper, the elastodynamic model of the tube array is formulated using the finite element approach, wherein each tube is modeled by a set of finite tube-elements. The interaction between tubes in the bundle is represented by fluidelastic coupling forces, which are defined in terms of the multi-degree-of-freedom elastodynamic behavior of each tube in the bundle. A laboratory test rig with an instrumented square bundle is constructed to measure the fluidelastic coefficients used to tune the developed dynamic model. The test rig admits two different test bundles; namely the inline-square and 45o rotated-square tube arrays. Measurements were conducted to identify the flow-induced dynamic coefficients. The developed scheme was utilized in predicting the onset of flow-induced vibrations, and results were examined in the light of TEMA predictions. The comparison demonstrated that TEMA guidelines are more conservative in the two configurations considered.
2 citations
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