Experimental flow perturbation analysis for single vibrating tube in a tube array subjected to turbulent shear flow

Flow-induced vibrations in heat exchanger tube bundles pose a serious challenge for the process sector, potentially resulting in premature structural failure, performance deterioration, and substantial economic losses. Purpose: Flow Induced Vibrations in heat exchangers is one of the major causes of structure failure resulting in efficiency reduction and huge economics losses for the process industry. For last few decades, research has been focused on analysis of flow induced vibrations in tube arrays in order to determine their operational life and the prediction of failures. It has been established that different geometric and flow parameters effect the response of the tube array when subjected to cross flow. The main aim of this work is to experimentally measure the interplay between internal flow disturbances and tube vibration response at varying upstream turbulence intensities. Method: The current study is focused on flow perturbation analysis inside parallel triangular tube array subjected to different levels of upstream turbulence intensities (0.7% and 16.5%). Tube array with pitch ratio of 1.375 has been utilized in the current experiments. Monitored tube is instrumented with triaxial accelerometer to capture the vibration response and hotwire anemometer has been used for performing upstream and internal velocity measurements. These experiments have been performed in open loop wind tunnel with the upstream velocity ranging between 0 and 8.9 m/s and subsequent reduced velocity ranges from 0 to 80. A lot of attention is paid to finding vibration stability characteristics and how velocity perturbations behave over a large range of lowered velocities. Results: The experimental findings demonstrate a significant correlation between velocity disturbances and vibrational response inside the tube array. From the analysis, it has been observed that vibration response is strongly dependent on the tube diameter and gap between tubes rather than pitch ratio. It has also been established that velocity perturbation amplitudes are highly dependent on the upstream turbulence intensity and vibration amplitudes of the monitored tube. Moreover, the stability threshold of the monitored tube tends to be delayed at higher upstream turbulence intensity of 16.5% owing to the lower mean velocity along the flow path. Conclusion: In conclusion, the velocity perturbation and vibration amplitudes are strongly correlated especially for lower upstream turbulence intensity (0.7%) resulting in accurate identification of flow attachment and detachment location as compared to higher upstream turbulence intensity (16.5%) resulting in considerable stability threshold delay in later case. These results give us significant information for making tube arrays that work better and are safer in real-world heat exchanger situations where there is cross-flow.