Heat transfer and flow characteristics of fluids in wavy-walled tubes under the combined effect of vibrations and pulsations

Abstract

In this paper, numerical simulation is used to investigate the effect of the new composite enhanced heat transfer-vibrating flow field and pulsating flow field synergistically on the heat transfer and flow characteristics of the fluid in the wavy-walled tube. By changing the parameters such as Reynolds number and pulsation amplitude A_m, the variations of the enhanced heat transfer coefficient E_h, the performance evaluation index PEC and the field synergy coefficient F_c are obtained to investigate the influencing factors of fluid flow and heat transfer. The results show that the synergistic effect of vibration and pulsation can significantly increase the range of vortex distribution and the average temperature inside the wavy-walled tube, and importantly, the enhanced heat transfer coefficient E_h is increased up to 36.2 % compared to a single pulsating flow field, suggesting that it better promotes the heat exchange between the fluid and the tube wall. Increasing the pulsation amplitude A_m can improve the vortex strength and heat transfer effect in the wavy-walled tube, and the PEC can reach up to 1.26, which means that the vibration-pulsation synergistic effect can improve the comprehensive heat transfer performance of the wavy-walled tube compared with a single pulsation flow field, and the PEC increases with the increase of pulsation amplitude A_m, and then slows down with the increase of the Reynolds number Re. F_c decreases with increasing Reynolds number Re and increases with increasing pulsation amplitude A_m. This work not only provides an effective method for heat transfer performance enhancement of heat exchanger tubes, but also provides an important reference for the development and application of multiple enhanced heat transfer technologies.