基于分子动力学的脉管气体振荡模拟及实验研究

Pulse Tube Gas Oscillation Based on Molecular Dynamics Simulation and Experimental Research

摘要: 随着科学技术的快速更迭，脉管制冷机在低温领域中的应用越来越广泛。本文基于分子动力学，对脉管内高低压He气的振荡过程进行模拟仿真，针对压缩过程，研究了脉管轴向温度波、速度波、压力波及质量流波随时间的变化，并对不同充放气频率下脉管冷端温度随时间的变化进行了实验探究。结果表明：模型内各点气体温度、速度均以正弦波的形式随时间呈现周期性变化，温度波变化趋势同实验结果一致。模型冷热端压力、质量流相位差不同，说明微脉管自身具备调相能力。另外实验结果显示，脉管自身存在最佳充放气频率，适当增加频率值有利于脉管制冷机制冷性能的提高。

Abstract: With the rapid changes in science and technology, pulse tube refrigerators are more and more widely used in the field of cryogenics. Based on molecular dynamics, this paper simulates the oscillation process of the high and low pressure He gas in the pulse tube. Aiming at the compression process, the changes of the axial temperature wave, velocity wave, pressure wave and mass flow wave of the pulse tube over time are studied. The temperature change of the cold end of the pulse tube with time under the deflation frequency was investigated experimentally. The results show that the gas temperature and velocity at each point in the model change periodically with time in the form of a sine wave, and the changing trend of the temperature wave is consistent with the experimental results. The pressure and mass flow phase difference between the cold and hot ends of the model are different, indicating that the micropulse tube itself has the ability of phase modulation. In addition, the experimental results show that the pulse tube itself has the best charging and discharging frequency, and an appropriate increase in the frequency value is beneficial to the improvement of the cooling performance of the pulse tube refrigerator.