节流制冷器自调机构低温形变特性分析

Performance analysis of the cryogenic characteristics of self- regulating part of small J- T cryocooler

微小型节流制冷器具有体积小、重量轻、可靠性高、启动速度快、冷端无运动部件等突出优势,在红外探测器、红外导引头以及其他电子器件冷却领域实现了大量应用。自调式节微型流制冷器特有的自调机构通过感应节流后温度变化来进行流量(制冷量)的调节,不仅能够有效利用有限的循环工质获得最大的制冷量,而且能够实现高的温度稳定性。为了实现对自调式微型节流制冷器自调机构形变的量化分析,指导自调机构波纹管选型,文中针对内充式自调机构充压波纹管建立了三维数值模型,采用变物性参数,分析了不同充注工质及不同波纹管材料下的低温条件形变特性。研究结果表明,所建立的数值分析模型预测结果与实际测量误差在5%以内,证实了模型的准确性。波纹管是自调机构发生形变的主要部件,除充注压力外,自调机构温度分布的不均匀,对于其形变特性也有一定影响。

With the advantages of small size, light weight, high reliability, quick start and the cold end without moving part, small and micro J - T cryocooler is widely applied in many areas, such as infrared detector, infrared seeker and some elec- tronic devices. With the regulating part, self-regulated J- T cryocooler can achieve the adjustment of system mass flow rate, which can help to obtain the maximum system cooling capacity and much better temperature distribution. In order to lead way for engineers to the convenient and effective design of a self - regulating structure for J - T cryocooler, this paper set up the 3D mod- el for the main part of the self - regulating structure. The performance of self - regulating structures with different working fluid, different charger pressure and different material was analyzed with variable working fluid properties. A maximum 5% error with the experimental data validated the reliability of the present numerical model. And the bellows contributed most of the deformation for the self - regulating system of the J - T cryocooler. Besides, the inner pressure and the difference of the temperature distribu- tion had something to do with the operating properties of the self - regulating structure.