Heat Transfer in Acoustic Resonance Tube and Its Application to Small-Capacity Refrigerator.

由于环境方面的重要性，人们越来越注意开发用于空间和其他小容量应用的声共振制冷机。本项目着重于热声学对传热机理的基本理解。建立了由声学致动器、共振管和堆叠组成的模拟声学制冷机模型，并测量了声学特性和沿堆叠的温度分布。本课题的研究结果总结如下：当使用氦气或氮气作为工作流体时，整个堆的最大温差达到30 K。声学驱动器的改进将提高冰箱实用化的可能性。利用线性化声学理论可以很好地预测声场，但在较高声幅下，线性化理论的预测结果较差。对模型进行改进，使之考虑了非线性效应，更重要的是，即使在高振幅区域，也能预测声场的基本特性。声波振幅、声波长度以及相对于声波振幅分布的声波位置对温度分布有显著影响。叠板间的距离对叠板间的温差和声波的相位差等热声特性有重要影响。存在一定的最佳堆板距离。当声幅较低时，线性化热声理论可以很好地预测温度分布，而在高幅时，非线性效应对温度分布的影响显著。考虑声雷诺应力的影响以及由此产生的声流和涡旋扩散系数，对预测模型进行了改进，使其与实验结果更加吻合。在堆面传热方面还需要进一步的实验研究，但本项目的结果对热声制冷机的主要特性有了满意的认识。少

Increasing attention has been given to the development of an acoustic resonance refrigerator for space use and other applications of small-capacity, owing to the environmental importance. This project focused on the fundamental understanding of the heat transfer mechanism by thermo-acoustics. A simulated acoustic refrigerator model was constructed, consisting of an acoustic actuator, a resonance tube and a stack, and acoustic characteristics as well as the temperature distribution along the stack were measured. The results obtained in this project were summarized as follows.1. Maximum temperature difference across the stack reached 30 K,using helium or nitrogen gas as a working fluid. The Improvement of acoustic actuator will make the possibility of practical refrigerator high.2. The acoustic field was well predicted using a linearized acoustic theory, while the linearized theory gave poor results at higher acoustic amplitude. Improving the model to taking into account the nonlinear ef … More fect, the fundamental characteristics of acoustic field could be predicted even at high-amplitude region.3. Temperature distributions along the stack were significantly affected by the acoustic amplitude, stack length, the position of stack relative to the amplitude distribution. The distance between successive stack plates plays an important role on the thermo-acoustic behavior including the temperature difference as well as the phase difference of acoustic wave across the stack. Some optimum stack-plate distance existed. When the acoustic amplitude was at lower level, the linearized thermo-acoustic theory could well predict the temperature distribution, while at high amplitude non-linear effect became to have a significant influence on the temperature distribution. Taking into account the effect of acoustic Reynolds stress and resulting acoustic streaming and eddy diffusivity, the prediction model was improved to give better agreement with the experimental results. Further experimental investigation will be needed in the heat transfer at the stack surface, but the present results of this project gives satisfactory understanding of the principal feature of the thermo-acoustic refrigerator. Less