The Effect of Tube Layout on the Fluid-Elastic Instability of Tube Bundles in Crossflow

Abstract

Fluid-elastic instability is widely recognized as a mechanism which can cause rapid failure of tubes in shell and tube heat exchangers. The shellside flow velocity for the onset of the fluid-elastic whirling is commonly calculated from Connors’ formula provided that the instability factor is known. The literature contains several reported values of the instability factor for different tube bundles but these have been obtained from a variety of test configurations and this has led to some large discrepancies. This paper describes a systematic study of the effect of tube layout on the instability factor for sixteen tube bundles. The results presented show that the instability factor varies by a factor of 3 over the range of tube layouts tested. This paper concludes with a comparison of the results of the present study with values taken from the open literature.