渐缩型锥形脉管制冷机的二维数值研究

本文开发了二维可压缩交变流动的SIMPLEC计算程序,对渐缩型锥形脉管制冷机进行了二维数值研究,研究了锥度对脉管制冷机性能的影响。数值计算结果表明,对渐缩型锥形脉管,存在一最佳锥度,此时的制冷效果最好,当锥度大于最佳锥度时,制冷效果反而变差。另外本文还从脉管内流场的分布及二次流的角度揭示了锥形脉管能提高制冷机性能的原因及内在机理。一定锥度下的锥形脉管不但可以改变脉管内二次流的大小,还改变了脉管内二次流的分布情况,使脉管冷热端的二次流分布变得不均匀。这是一定锥度下的锥形脉管可以改善脉管制冷机制冷效果的主要原因。

TWO DIMENSIONAL NUMERICAL SIMULATION OF TAPERED PULSE TUBE REFRIGERATOR

Two-dimensional numerical simulation of the viscous compressible oscillating flow was carried out for the uniform cross-section and tapered pulse tubes by using a compressible SIMPLEC algorithm code developed by the authors. Effects of the taper angle on the performance of the pulse tube refrigeration were studied. The results showed that there was an optimum taper angle for tapered pulse tube refrigerator. With this optimum taper angle, the refrigerator performance can be improved a lot. But when the taper angle becomes larger than the optimum value, the cooling performance becomes inferior to that of the circular tube. The inherent mechanism of how the tapered pulse tube affects the performance of pulse tube refrigerator was also studied from the view point of second flow distribution in the pulse tube. Compared to the uniform cross-section pulse tube, the values of second flow in tapered pulse tube change a lot and the distribution of second flow becomes uneven as well. This is the main reason that the performance of tapered pulse tube can be improved compared to uniform cross-section Dulse tube.