微通道脉管非线性交变振荡微观机理的分子动力学研究

Microscopic Mechanism of Nonlinear Gas Alternating Oscillation in Microchannel Pulse Tube: Molecular Dynamics Study

采用分子动力学方法,对He在微通道脉管内的非线性交变振荡的热力学响应进行仿真,研究气体振荡诱导管内轴向压力梯度、温度场的形成,并阐述微通道长径比对温差与相位的影响.结果表明:微通道内伴随压差驱动力在管内形成类似正弦函数压力波、速度波、质量流量波与半正弦的温度波.振荡周期随脉管管径的增大而缩短,随脉管长度的增加而增长,受直径影响很小;微通道两端的时均温差随长度的增加而增大,受直径的影响很小.预测针对不同的脉管直径存在一个最佳长径比与振荡周期,其数值随直径的增大而增大,为优化脉冲管的性能提供理论依据.

Molecular dynamics simulation is used to simulate response of nonlinear sinusoidal alternation flow of helium gas oscillation in a pulse tube.Formation of axial pressure wave and temperature field inducted by gas oscillation was studied.Influence of length to diameter ratio on temperature difference and phase of cold and hot ends of the pulse tube is shown.It shows that the pressure wave,speed wave and mass flow wave accompanying by driving force are similar to a sinusoidal function while the temperature wave is similar to a half-sinusoidal function.The oscillation period is shortened with increase of the diameter of the tube and prolonged with increase of the length of the tube.The maximum temperature difference between hot end and cold end increases with the length of the tube but independent of diameter.It is predicted that there is an optimal aspect ratio and oscillation period for pulse tube with different diameter,which increases with increasing of the diameter.It provides a theoretical basis for optimizing efficiency of pulse tube.