脉管制冷机内自然对流影响的数值分析

通过对脉管内自然对流的数值模拟，在相同的冷、热端温度条件下，研究重力的方向对脉管内自然对流的流场、温度场及脉管内热交换的影响，并进行了对比分析。采用二维圆柱坐标，引入Boussinesq假设，计算稳态的自然对流。计算表明，冷端在下（冷面朝上）时，自然对流对脉管内的换热有抑制的作用，有利于保持两端的温差，从而使得在冷端与冷端温度相同、热端与热端温度相同的情况下，冷端在下时端部所需的导热量是冷端在上时的31％。这一结论与实验测试结果一致。所做的理论分析对脉管制冷机的良好运行有指导意义。

Numerical Analysis of the Effect of Natural Convection in Pulse Tube

Natural convection in a pulse tube was numerically simulated to analyze how the direction of the buoyancy force affects the flow and temperature distributions. 2D cylindrical coordinates and the Boussinesq assumption were applied in this computation for the steady natural convection. Computational result shows that when the cold end is at the bottom, the natural convection in the tube inhibits the heat exchange and helps to hold the temperature difference at the two ends. The heat to be conducted at the ends where the cold end is at the bottom is only 31% of that where the cold end is at the top. This result is in good agreement with the experiments. This analysis may be used to enhance the performances of a pulse tube refrigerator.