Talebi Maryam, Setareh Milad, Saffar-Avval Majid, Hosseini Abardeh Reza
Department of Mechanical Engineering, Amirkabir University of Technology, 424, Hafez Ave, P.O. Box 15875-4413, Tehran, Iran.
Department of Mechanical Engineering, Amirkabir University of Technology, 424, Hafez Ave, P.O. Box 15875-4413, Tehran, Iran.
Ultrasonics. 2017 Apr;76:52-62. doi: 10.1016/j.ultras.2016.12.010. Epub 2016 Dec 18.
Application of ultrasonic waves for heat transfer augmentation has been proposed in the last few decades. Due to limited researches on acoustic streaming induced by ultrasonic oscillation, the effect of ultrasonic waves on natural convection heat transfer is the main purpose of this paper. At first, natural convection on up-ward-facing heating surface in a cylindrical enclosure filled with air is investigated numerically by the finite difference method, then the effect of upper surface oscillation on convection heat transfer is considered. The conservation equations in Lagrangian approach and compressible fluid are assumed for the numerical simulation. Results show that acoustic pressure will become steady after some milliseconds also pressure oscillation amplitude and acoustic velocity components will be constant therefore steady state velocity is used for solving energy equation. Results show that Enhancement of heat transfer coefficient can be up to 175% by induced ultrasonic waves. In addition, the effect of different parameters on acoustic streaming and heat transfer has been studied.
在过去几十年里，人们提出了应用超声波来强化传热。由于对超声振荡引起的声流研究有限，本文主要研究超声波对自然对流换热的影响。首先，采用有限差分法对充满空气的圆柱形封闭腔内朝上加热表面的自然对流进行了数值研究，然后考虑了上表面振荡对对流换热的影响。数值模拟采用拉格朗日方法和可压缩流体的守恒方程。结果表明，经过几毫秒后声压将趋于稳定，压力振荡幅度和声速分量也将保持恒定，因此使用稳态速度来求解能量方程。结果表明，超声波诱导可使传热系数提高达175%。此外，还研究了不同参数对声流和传热的影响。
