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Shock and Vibration
Volume 2016, Article ID 1680218, 20 pages
http://dx.doi.org/10.1155/2016/1680218
Research Article

Fluid-Elastic Instability Tests on Parallel Triangular Tube Bundles with Different Mass Ratio Values under Increasing and Decreasing Flow Velocities

Xu Zhang,1,2,3 Bin Jiang,1,2,3 Luhong Zhang,1,3 and Xiaoming Xiao1,3

1School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
2National Engineering Research Center for Distillation Technology, Tianjin 300072, China
3Tianjin Collaborative Innovation Center of Chemical Science and Engineering, Tianjin 300072, China

Received 26 May 2016; Revised 6 August 2016; Accepted 28 September 2016

Academic Editor: Marco Belloli

Copyright © 2016 Xu Zhang et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

To study the effects of increasing and decreasing flow velocities on the fluid-elastic instability of tube bundles, the responses of an elastically mounted tube in a rigid parallel triangular tube bundle with a pitch-to-diameter ratio of 1.67 were tested in a water tunnel subjected to crossflow. Aluminum and stainless steel tubes were tested, respectively. In the in-line and transverse directions, the amplitudes, power spectrum density functions, response frequencies, added mass coefficients, and other results were obtained and compared. Results show that the nonlinear hysteresis phenomenon occurred in both tube bundle vibrations. When the flow velocity is decreasing, the tubes which have been in the state of fluid-elastic instability can keep on this state for a certain flow velocity range. During this process, the response frequencies of the tubes will decrease. Furthermore, the response frequencies of the aluminum tube can decrease much more than those of the stainless steel tube. The fluid-elastic instability constants fitted for these experiments were obtained from experimental data. A deeper insight into the fluid-elastic instability of tube bundles was also obtained by synthesizing the results. This study is beneficial for designing and operating equipment with tube bundles inside, as well as for further research on the fluid-elastic instability of tube bundles.