小流量高扬程低温液体泵的流动传热特性研究

In order to better meet the requirements of cryogenic superconductivity and cold neutron source, the recycling driving force of cryogenic fluid has been improved continuously. Therefore, cryogenic centrifugal pump is widely used in cryogenic superconducting devices and cold neutron source system, which greatly improved its heat transfer performance of those cryogenic equipments. This study intends to explore the fluid characteristic and heat transter mechanism for low flow rate and high head centrifugal pump, based on theoretical analysis and experimental measurements, in order to develop the critical technical proposals for cryogenic centrifugal pump, further on lay foundation for the development of cryogenic centrifugal pump. Proposed by investigating the fliud characteristic and heat transfer mechanism, to determine proper structures for important components of cryogenic liquid pump (such as liquid hydrogen pump, liquid helium pump), as well as confirm the sealing structure, and efficient and feasible thermal insulation approach. On the basis of the above research, this project proposed to set up an experimental platform, and then test the hydraulic and thermal dynamic performance of liquid hydrogen pump, to verify the reliability of theoretical research. The novelty of this research, lies in the quantitative resolution of the flow and thermal insulation structure for cryogenic liquid centrifugal pump, as well as the mechanism of stability and failure of the impeller.

为了更好的满足低温超导和冷中子源的要求，低温工质的循环驱动力一直不断的在提高，为此，低温液体离心泵被广泛应用于低温超导设备和冷中子源系统中，大大提高了超导设备和冷中子源的换热性能。本项目拟通过理论分析与实验测量相结合的方法来研究小流量高扬程低温液体循环泵的流动特性和传热机理，其学术思想在于通过确定各关键技术方案，为解决深低温温区低温离心泵研制中的科学问题奠定基础。拟通过考察离心泵叶轮在低温下的高速流动特性以及轴向传热机理，为低温液体泵（液氢泵、液氦泵）各重要部件选定合适的结构，明确支撑密封方式的选择，选定高效可行的绝热方式。在上述研究的基础上，拟搭建低温液氢循环泵测试实验台，并实验测量液氢泵的流动传热性能，以验证理论研究的可靠性。在此基础上定量解析低温液体循环泵的流动绝热结构，提出叶轮稳定性及失效的机理，是本研究的创新之处。

本研究将以一低温液氢循环泵为研究对象，针对低温液氢离心泵叶轮内部的流动特性及叶轮的设计优化开展研究，揭示小流量高扬程低温液体循环泵的流动特性。针对低温液氢循环泵的轴向传热机理开展研究，提出最优绝热技术方案。最后通过实验测量低温液氢泵的水力性能等，以验证理论分析的可靠性。项目研究重要结果主要包括：（1）低温液体循环泵流动特性的研究：相比于后弯式叶片，直叶片叶轮具有较高的效率和满足条件的压比。（2）低温液体循环泵绝热技术的研究：循环泵绝热结构中，固体的导热占据主导。其中热铆的设计，能够大幅减小了轴向氢空间的低温漏热损失。根据相关计算结果，给出了最佳绝热方案，即采用空心杆连接室温端电机和低温端叶轮，空心杆内为氢气填充。空心杆外侧设置热铆结构，热铆之间采用G-10材料填充。（3）低温液体循环泵水力性能的实验研究：采用0.8 MPa的冷氮气模拟1.5 MPa@20 K的液氢设计工况时，根据实验测量的泵的扬程、功率及效率，换算成设计工况下泵的扬程约150 m，功率约为185 W，效率约35%，符合设计要求。通过实验测量低温液体泵的水力性能，验证了理论分析的可靠性。.本项目研究涉及的流动及传热特性研究，为解决深低温温区离心泵的研制和应用奠定了基础。