Said Seid

Bio: Said Seid is an academic researcher from King Fahd University of Petroleum and Minerals. The author has contributed to research in topics: Bundle. The author has an hindex of 1, co-authored 1 publications receiving 2 citations.

The onset of flow-induced vibrations in a square tube array subjected to cross-flow

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.

Fluid damping and fluid stiffness of tube arrays in crossflow

Abstract: Motion-dependent fluid forces acting on a tube array were measured as a function of excitation frequency, excitation amplitude, and flow velocity. Fluid-damping and fluid-stiffness coefficients were obtained from measured motion-dependent fluid forces as a function of reduced flow velocity and excitation amplitude. The water channel and test setup provide a sound facility for obtaining key coefficients for fluidelastic instability of tube arrays in crossflow. Once the motion-dependent fluid-force coefficients have been measured, a reliable design guideline, based on the unsteady flow theory, can be developed for fluidelastic instability of tube arrays in crossflow.