脉冲管整机条件下回热器交变特性实验研究

Experimental research on regenerator characteristics under oscillating flow in pulse tube cryocooler

搭建脉冲管制冷机动态参数测试实验台,在脉冲管制冷机整机运行条件下对处于实际温度梯度的回热器进行了动态速度以及动态压力测试。为了测量回热器冷端的动态速度,研究针对低温侧的热线探针进行了低温条件下的标定。实验测量了充气压力3 MPa、运行频率40—60 Hz、冷端温度100 K工况下回热器的相位特性以及阻力特性,并得到了整机运行条件下回热器阻力系数经验公式。研究结果表明,随着频率的提升,回热器冷热端速度-压力相位差增大,相同雷诺数下的阻力系数增大;随着温度降低,相同雷诺数下的阻力系数增大,并且在低雷诺数下变化更加明显。该研究结果是在回热器实际工作条件下测量得到,能够为脉冲管制冷机中的回热器模拟计算以及回热器热力学分析提供必要的数据支持。

In order to study the characteristics of regenerator under oscillating flow, a test platform of dynamic parameters in pulse tube cryocooler has been built. With this test platform, the dynamic velocity and pressure at the hot end and the cold end of the regenerator can be measured. A calibration experiment of the hot wire probe has been done at low temperature in order to get the conversion formula for hot wire probe at the cold end of the regenerator. The experiment has been operated under the conditions of 3 MPa, the operating frequency varied from 40 Hz to 60 Hz, the temperature of the cold end was 100 K, and the characteristics of the phase shift and resistance of regenerator have been studied. With the experiment data, the empirical formulas of the friction factor under the conditions of different operating frequencies have been obtained. The experiment results show that the phase shift between velocity and pressure of the regenerator increases as the frequency increases, so is the friction factor. As the temperature decreases, the friction fac- tor increases and the change is more obvious under the condition of low Reynolds number. Since the results are obtained under the conditions of actual temperature distribution and phase shift of the regenerator, they are more applicable for regenerator in pulse tube cryocooler, and the results are meaningful for design and optimization of regenerator in pulse tube cryocooler.