EXPERIMENTAL STUDY ON FLUID-ELASTIC INSTABILITY IN A HEAT EXCHANGER TUBE BUNDLE HAVING A NORMAL TRIANGULAR TUBE ARRANGEMENT, SUBJECTED TO CROSS FLOW OF WATER

Abstract

Flow-induced vibration is a crucial consideration in the design of thermal-hydraulic apparatus. The nuclear, industrial, and power industries have expressed considerable worry regarding heat exchangers that may encounter elevated liquid or gas flow rates. Heat exchangers are tube bundles with multiple geometric arrangements, subjected to cross-flow. The tubes within a bundle represent the most flexible elements of the structure. Heat exchangers and steam generators have incurred damage from severe flow-induced vibrations. Flow-induced vibration mechanisms fail through mechanical wear, fretting, and fatigue cracking, ultimately causing tube leakage. Expensive plant shutdowns have led to studies into fluid cross-flow caused vibrations in steam generators and process heat exchangers. The current research investigated the effect of fluid elastic instability in heat exchangers using a regular triangular tube arrangement. Connor’s equation was used to derive the relation between critical reduced velocity and mass damping parameters and to plot stability maps for a reduced velocity range of 1.19 to 5.97 m/s using a regular triangular tube arrangement. After doing amplitude, spectrum, and stability analysis, it is concluded that for the given case study (P/D=1.45, tube dia.=16mm), instability of the tube against the reduced velocity is more in both parallel and perpendicular flow directions when the tube was placed in the second row of the tube bundle.