For a pulse tube cryocooler, the expansion efficiency of the pulse tube is important and is strongly related to the flow inside. Conventionally, flow straighteners are used at both ends of the empty pulse tube to ensure a uniform flow. This approach complicates the system and also becomes a source of flow losses. In this paper, a partly tapered pulse tube that has a tapered section at the ambient end is used to replace the flow straightener. Its performance was compared with that of a conventional straight pulse tube without or with flow straightener at the ambient end numerically and experimentally. Simulation results show that the flow straightener is necessary in the straight pulse tube due to the influence of jet-driven streaming in the location where abrupt cross-sectional area change occurs. The partly tapered pulse tube can effectively eliminate the need for flow straightener. The expansion efficiency is the highest (about 94%) for the partly tapered pulse tube, while an efficiency of 88% is obtained with the straight pulse tube with a flow straightener. Experiments have been conducted; the cooling power of the straight pulse tube without flow straightener, the straight pulse tube with flow straightener, and the partly tapered pulse tube is 3.9, 28, and 29 W, respectively. The cooling power of the straight pulse tube with flow straightener and that of the partly tapered pulse tube are almost the same, which indicates that the partly tapered pulse tube can effectively eliminate the need for an ambient flow straightener.

对于脉冲管低温冷却器，脉冲管的膨胀效率很重要，并且与内部流量密切相关。常规地，在空脉冲管的两端使用整流器以确保均匀的流动。这种方法使系统复杂化，并且也成为流量损失的来源。在本文中，使用在环境末端具有锥形截面的部分锥形的脉冲管来代替整流器。在数值和实验上，将其性能与在环境端不带或带有整流器的传统直脉冲管的性能进行了比较。仿真结果表明，由于在横截面积突然变化的地方喷射驱动流的影响，在直脉冲管中必须使用整流器。部分锥形的脉冲管可有效消除对整流器的需要。对于部分锥形的脉冲管，膨胀效率最高（约94％），而带有整流器的直脉冲管的膨胀效率为88％。实验已经进行；不带整流器的直脉冲管，带整流器的直脉冲管和部分锥形脉冲管的冷却功率分别为3.9 W，28 W和29W。带有整流器的直脉冲管的冷却功率与部分锥形的脉冲管的冷却功率几乎相同，这表明部分锥形的脉冲管可以有效地消除对环境整流器的需要。对于部分锥形的脉冲管，膨胀效率最高（约94％），而带有整流器的直脉冲管的膨胀效率为88％。实验已经进行；不带整流器的直脉冲管，带整流器的直脉冲管和部分锥形脉冲管的冷却功率分别为3.9 W，28 W和29W。带有整流器的直脉冲管的冷却功率与部分锥形的脉冲管的冷却功率几乎相同，这表明部分锥形的脉冲管可以有效地消除对环境整流器的需要。对于部分锥形的脉冲管，膨胀效率最高（约94％），而带有整流器的直脉冲管的膨胀效率为88％。实验已经进行；不带整流器的直脉冲管，带整流器的直脉冲管和部分锥形脉冲管的冷却功率分别为3.9 W，28 W和29W。带有整流器的直脉冲管的冷却功率与部分锥形的脉冲管的冷却功率几乎相同，这表明部分锥形的脉冲管可以有效地消除对环境整流器的需要。带有整流器的直脉冲管和部分锥形的脉冲管分别为3.9 W，28 W和29W。带有整流器的直脉冲管的冷却功率与部分锥形的脉冲管的冷却功率几乎相同，这表明部分锥形的脉冲管可以有效地消除对环境整流器的需要。带有整流器的直脉冲管和部分锥形的脉冲管分别为3.9 W，28 W和29W。带有整流器的直脉冲管的冷却功率与部分锥形的脉冲管的冷却功率几乎相同，这表明部分锥形的脉冲管可以有效地消除对环境整流器的需要。