【作者】 寿琳；

【导师】 陈国邦；

【作者基本信息】 浙江大学 ， 制冷及低温工程， 2007， 硕士

【摘要】 热声驱动脉管制冷机这种无机械运动部件的新型制冷系统已经成为制冷与低温学术领域的研究热点，并且也受到了工业界的关注。该系统没有机械运动部件，具有结构简单、运行可靠、无污染等优点。本文首先回顾了热声热机的发展历史及其应用前景，介绍了热声理论的研究进展，分析了研究非线性热声理论的必要性，并总结了非线性热声理论的研究进展。在此基础上，重点开展了以下研究工作：1)分别介绍了驻波型热声发动机改进前后的加热器、水冷器和高温气库的结构、作用及其对热声系统性能的影响。2)对改进前后的热声发动机系统在未带负载、带声压放大器加阻容(RC)负载、带声压放大器加脉管制冷机三个方面的性能分别进行了比较和分析。发现改进后的热声发动机系统能带动更长的声压放大器，在更高的加热功率下工作，使得声压放大器出口处能得到更大的压比和压力振幅，系统能够提供给RC负载的最高声功增大，脉管制冷机能够达到的最低制冷温度降低到75.62K，比改进前所能达到的最低制冷温度79.7K进一步降低。3)对声压放大器的压力放大作用进行了理论分析。并通过数值模拟及实验探讨声压放大器长度变化对热声发动机系统性能的影响，发现在RC负载声阻不同的范围内，系统的性能随着声压放大器长度的变化趋势有很大差别。4)总结了在实验中观察到的频率跳变现象。通过对频率跳变现象的总结，将驻波型热声系统的运行模式分类，对跳频现象出现的声阻范围、跳频现象随输入功率的变化关系以及跳频现象和声压放大器长度的关系进行了分析和总结。并且采用S．karpov和A．Prosperetti等人提出的弱非线性模型对实验中出现的频率跳变现象进行了定性的分析和解释，并发现实验结果基本符合该非线性模型的理论分析。更多还原

【Abstract】 A thermoacoustically driven pulse tube refrigerator, which has no moving parts, is attracting more and more interest of academic circles and industry. This new concept refrigerator occupies outstanding advantages of simplicity, reliability, stability, longevity, no pollution and so on.This paper reviews the developments and applications of thermoacoustic engines, introduces the research development of thermoacoustic theories, analyzes the significance of the exploration of non-linear thermoacoustic theory and concludes the development of the non-linear thermoacoustics. Then, The following sections are carried out:1) The structure, function and the influence on the performance of thermoacoustic engine of heaters, water-coolers, and hot buffers of both the former and present standing-wave thermoacoustic engine have been discussed respectively.2) The performances of the former and present thermoacoustic engines without load, thermoacoustic engine driven RC (Resistance and Capacitance) load with the pressure amplifier and thermoacoustic engine driven pulse tube refrigerator have been compared and analyzed. According to the results of experimentation, it is found that the present thermoacoustic engine can drive a longer pressure amplifier, work under higher heating power and provide bigger pressure ratio and pressure amplitude at the outlet of the pressure amplifier. Consequently, the maximum acoustic power supplied to the RC load by the present thermoacoust engine is increased compared with the former system. The pulse tube refrigerator driven by the present thermoacoustic engine has achieved a cooling temperature as low as 75.62K, lower than that of 79.7K which is achieved with the former engine.3) The effect on amplifying pressure of the acoustic pressure amplifier is analyzed theoretically. The influence of length of the pressure amplifier on the performance of the standing-wave thermoacoustic engine was simulated and investigated experimentally. It is shown that in two different ranges of acoustic resistance, the performance of the system along with the increase of the length of the pressure amplifier greatly differences from each other.4) Firstly, the phenomena of frequency shift that is observed in the experiment is concluded and the operating patterns of the standing-wave thermoacoustic system are classified and defined respectively. Then, the range of acoustic resistance in which frequency shifts, the relationship between frequency shift and input power and the relationship between frequency shift and the length of the acoustic pressure amplifier are analyzed and concluded. Eventually, a weakly nonlinear theory of the thermoacoustic instability which was proposed by S. karpov, A. Prosperetti et al. is used to qualitatively analyze and explain the phenomena of frequency shift. The results of experiments are found to be basically in accordance with the weakly nonlinear theory.更多还原