Document Type

Conference Proceeding

Publication Date

1-2007

Keywords

Cross-flow, Damping, Flow (Dynamics), Fluctuations (Physics), Fluids, Porosity, Water, Densitometers, Density, Electromagnets, Equilibrium (Physics), Phase transitions, Pressure, Stability, Steam

Abstract

An experimental study was conducted to investigate damping and uidelastic instability in tube arrays subjected to twophase cross-ow. The purpose of this research was to improve our understanding of these phenomena and how they are affected by void fraction and ow regime. The working uid used was Freon 11, which better models steam-water than air-water mixtures in terms of vapour-liquid mass ratio as well as permitting phase changes due to pressure uctuations. The damping measurements were obtained by plucking the monitored tube from outside the test section using electromagnets. An exponential function was tted to the tube decay trace, producing consistent damping measurements and minimizing the effect of frequency shifting due to uid added mass uctuations. The void fraction was measured using a gamma densitometer, introducing an improvement over the Homogeneous Equilibrium Model (HEM) in terms of density and velocity predictions. It was found that the Capillary number, when combined with the total damping ratio (interfacial damping), shows a well dened behaviour depending on the ow regime. This observation can be used to develop a better methodology to normalize damping results. The uidelastic results agree with previously presented data when analyzed using the HEM and the half-power bandwidth method. The interfacial velocity is suggested for uidelastic studies due to its capability for collapsing the uidelastic data. The interfacial damping was introduced as a tool to include the effects of ow regime into the stability maps.

Comments

PVP2007 ASME 2007 Pressure Vessels and Piping Division Conference

July 22-26, 2007, San Antonio, TX, U.S.A.

Faculty

Faculty of Applied Science & Technology (FAST)

Peer Reviewed/Refereed Publication

yes

Terms of Use

Terms of Use for Works posted in SOURCE.

Creative Commons License

Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.

Original Publication Citation

Moran, J. & Weaver, D. S. (2007). " On Damping and Fluidelastic Instability in a Tube Bundle Subjected to Two-Phase Cross-Flow."
Proceedings of the ASME 2007 Pressure Vessels and Piping Conference Volume 4: Fluid-Structure Interaction. pp. 429-438. ASME. https://doi.org/10.1115/PVP2007-26458

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