MICRO-HEAT TRANSFER MECHANISM IN A BOUNDARY LAYER INDUCED BY ACOUSTIC OSCILLATION AND THE DEVELOPMENT OF THERMOACOUSTIC THEORY

声振荡引起的边界层微传热机制及热声理论发展

基本信息

批准号：
09650257
负责人：
OZAWA Mamoru
金额：
$ 1.92万
依托单位：
KANSAI UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1998
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09650257/
关键词：
Acoustic refrigerator Temperature distribution along stack Acoustic streaming Heat transfer Control of phase lag Flow visualization Osccillation boundary layer スタック熱伝逹バイパス可視化

项目摘要

It is well known that the boundary layer is formed by a sinusoidal oscillation. The thickness of this boundary layer (referred to as the depth of penetration) and thermal flow behavior there control the system performance of acoustic resonance-tube refrigerator. The scaling parameters of such heat transfer are derived based on the theoretical and numerical analysis as follows : the Prandtl number, the oscillation Reynolds number, the Strohal number with respect to the amplitude of fluid oscillation and the stack distance, the Strohal number with respect to the amplitude and the stack length and the heat capacity ratio of the stack and the fluid. Comparison between the experimental data of temperature distribution along the stack and the linearized thermoacoustic theory indicated a prime importance of the Strohal number. One of the important factors related to the Strohal. number is an acoustic streaming induced by the existence of fluid viscosity. Then the flow visualizing study was conducted to look insight into the influence of the stack on the streaming. The acoustic streaming showed characteristic feature that two vortices appeared at both sides of the stack and moreover that these two vortices were combined with each other by the through flow between them. This suggested the importance to take such vortices and through flow into account in the development of prediction model. Alternative approach to improve the performance is the control of the phase difference between the velocity and pressure fluctuation, and/or veloci es at both ends of the stack. One of the typical techniques is to install the by-pass between the acoustic driver and the closed end of the resonance tube. Then the by-pass with a resonance box has shown the potential to improve the performance.

众所周知，边界层是由正弦振荡形成的。该边界层的厚度（称为穿透深度）和热流动行为控制了声学共振管冰箱的系统性能。这种热传递的缩放参数是基于理论和数值分析得出的，如下所示：prandtl数量，振荡雷诺数，相对于流体振荡幅度和堆栈距离的振幅，静态距离的振幅，静态数量和堆栈长度和热容量和热量率和流体的静态比例。沿堆栈温度分布的实验数据与线性化热声理论之间的比较表明，斯特罗哈尔数的重要性。与Strohal有关的重要因素之一。数字是由流体粘度的存在引起的声学流。然后进行了可视化研究，以深入了解堆栈对流媒体的影响。声流的特征表明，堆栈的两侧出现了两个涡流，此外，这两个涡流通过它们之间的贯穿流程相互结合。这表明在预测模型的开发中考虑了这种涡旋并通过流动考虑的重要性。改善性能的替代方法是控制速度和压力波动之间的相位差，以及堆栈两端的速度。典型的技术之一是在声学驱动器和谐振管的封闭端之间安装旁路。然后，带有共振框的旁路表明了提高性能的潜力。