Experimental investigation of vibration attenuation in the shell-side flow of a shell-and-tube heat exchanger through drag-reducing additives

The structural vibrations and hydrodynamic noise emissions originating from underwater vehicles fundamentally degrade their survivability through acoustic signature exposure. Shell-and-tube heat exchangers (STHE), which are commonly used on underwater vehicles, exhibit significant flow-induced vibrations when water flows across tube bundles in the shell side. This generates broadband acoustic emissions and critically impact the acoustic stealth characteristics of underwater vehicles. This study systematically examines flow-induced vibration characteristics and suppression mechanisms of three water-soluble drag-reducing additives—polyethylene oxide (PEO), xanthan gum (XG), and cetyltrimethylammonium chloride (CTAC)—through experimental characterization in STHEs. Based on the average vibration attenuation magnitude across all working conditions under the present experimental setup, PEO solution achieves superior vibration attenuation efficacy, outperforming CTAC solution with intermediate performance, whereas XG solution exhibits the least pronounced vibration attenuation capability. Using Particle image velocimetry (PIV), the velocity fields in the wake of flow past a circular cylinder and multi–tube bundles were captured for the 50 ppm PEO solution. Results show that the polymer can effectively suppress vortex shedding and reduce the intensity of turbulent fluctuations in the wake flow of the cylinder under the present experimental conditions. This reveals the principle of vibration attenuation for STHEs through polymer solutions.