微通道脉冲管中He气交替振荡的分子动力学模拟

使用非平衡分子动力学模拟方法分析了微通道脉冲管(MPT)中由正弦速度活塞提供驱动力时He气交替振荡的微观动力学过程,并对MPT的冷却机制进行了分析.结果表明,MPT的压缩和膨胀过程之间存在一个交替的振荡过程,两个过程具有不对称的属性分布,膨胀过程具有比压缩过程更大的轴向压力梯度.当充气压力较低时,循环时间对冷端温度的影响很小,但是当充气压力高于20 bar时,冷端温度对时间较为敏感,随着时间的减少,冷端温度进一步降低,而冷端瞬时平均温度随着充气压力的增加而增加.另外,压比随着时间的减少而增加,并且明显不受充气压力的影响,但它会在MPT的轴向上产生较大的温度梯度.综上所述,在热端使用不同形式的换热器和调相元件会释放或回收额外的声功率.固定工作模式和尺寸参数的MPT具有最佳频率,可以在冷端获得最低的空载温度.仿真结果增进了对脉冲管制冷机的认识,并为微通道脉冲管制冷机的优化设计提供理论支持.

Molecular dynamics simulation of alternating oscillation of He gas in a microchannel pulse tube

Using the non-equilibrium molecular dynamics simulation method, the micro-dynamic process of He gas alternately oscillating when the driving force is provided by the sinusoidal velocity piston in the microchannel pulse tube (MPT) is studied, and the cooling mechanism of MPT is studied. The results show that there is an alternating oscillation process between the compression and expansion processes of MPT, which two processes have an asymmetric property distribution. The expansion process has a larger axial pressure gradient than the compression process. When the charging pressure is low, the cycle time has little effect on the cold end temperature, but when the charging pressure is higher than 20 bar, the cold end temperature is more sensitive to time. As time decreases, the cold end temperature further decreases, and the cold end instantaneous average temperature at the end increases with the increase in inflation pressure. In addition, the pressure ratio increases with the decrease of time and is obviously not affected by the inflation pressure, but it will produce a larger temperature gradient in the axial direction of the MPT. In summary, using different forms of heat exchangers and phase shifters on the hot end will release or recover additional sound power. The MPT with fixed working mode and size parameters has the best frequency and can obtain the lowest no-load temperature at the cold end. The simulation results enhance the understanding of the cooling mechanism of the pulse tube and provide theoretical support for the optimal design of the microchannel pulse tube cooler.