Experimental and numerical study on heat transfer enhancement by Flow-induced vibration in pulsating flow

The combination of flow-induced vibration and pulsating flow has a greater potential to enhance heat transfer. This study aims to investigate the effect of flow-induced vibration using pulsating flow generated by a vortex generator on the heat transfer enhancement of planar elastic tube bundle (PETB) in three kinds of flow fields. Water was utilized as working fluid to study the vibration characteristic and heat transfer of PETB comprehensively in a laminar flow using the experimental platform of flow-induced vibration and two-way fluid structure interaction (FSI) calculation. Vibration results found that the main vibration frequency of PETB in three flow fields was mainly concentrated in 24-25 Hz and the vibration amplitude was most obviously affected by the pulsating flow, leading to an amplitude reduction of 18.5% and 51.75% in coupled flow, 62.2% and 59% in steady flow. The difference in constrain support caused the local vibration displacement on No.3 tube showing a trend of first decreasing and then increasing and the local vibration displacement on No. 4 tube presenting a gradually increasing trend. Findings indicated that there was the same variation trend between the vibrational Reynolds number and heat transfer enhancement. The pulsating flow enhanced the vibration intensity of PETB, resulting in a increase in the turbulence kinetic energy and variation in the vorticity patterns. As a result, the passive heat transfer enhancement using the flow-induced by pulsating flow was obtained with a heat transfer coefficient increase of 28%, 25% and 19.5% in pulsating flow, coupled flow and steady flow, respectively. The maximum difference in local heat transfer was obtained at the position near the big connecter, where the local heat transfer coefficients in pulsating flow and coupled flow were 11.4% and 2.8% higher than that in steady flow, respectively.