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采用计算流体力学(CFD)方法,对小型脉冲管制冷机进行了二维数值模拟,研究了脉冲管制冷机部件变截面处的结构非对称性对流场的影响。数值模拟结果观测到由非对称结构所引起的非对称流动,揭示了第三直流效应的产生机理,这种非对称流动以周期性演变的涡量环流的形式进行。涡量环流的演变是一个能量的耗散过程,文中还对比了不同输入功率和运行频率对涡量耗散的影响。此外,将数值模拟结果与实验实测结果进行对比,验证了数值模拟的有效性,并从涡量耗散的观点出发对小型脉冲管制冷机输入功率增加到一定程度后制冷温度升高的反常现象进行了解释。
A two-dimensional numerical simulation of a small pulse tube refrigerator was carried out by computational fluid dynamics (CFD) method. The influence of structural asymmetry on the flow field was investigated. The asymmetric flow induced by the asymmetric structure was observed by the numerical simulation results. The mechanism of the third DC effect was revealed. The asymmetric flow was in the form of cyclical vorticity circulation. The evolution of vorticity circulation is an energy dissipation process. The paper also compares the effects of different input powers and operating frequencies on the dissipation of vorticity. In addition, the numerical simulation results are compared with the experimental results to verify the effectiveness of the numerical simulation. From the point of view of vorticity dissipation, the anomalous phenomenon that the refrigeration temperature increases after the input power of the small pulse tube refrigerator is increased to a certain extent Explained.