高温差高过热度条件下螺旋管内沸腾两相流流动与传热特性研究

螺旋管式直流蒸汽发生器是新型核反应堆中能量传递的核心设备。现有关于螺旋管内两相流流动、传热、流动不稳定性等的研究均聚焦于特殊管型和条件，研究结果比较分散，未形成统一、通用的结论。在具有高温差高过热度的特殊新型螺旋管蒸汽发生器中，沸腾两相流传热、压降及并联螺旋管间流量分配和流动不稳定性等均呈现出新特点，需深入研究。对此，本项目拟对不同几何结构螺旋管内沸腾两相流的流动与传热特性开展系统的实验研究；在此基础上，基于两相流动力学分析，建立螺旋管内两相流含气率、传热、阻力的高精度计算模型以及蒸发器并联螺旋管组内两相流的流量分配和流动不稳定性的预测模型，提出流动不稳定性的分布图谱和脉动界限预测关系式。进一步开展动态变负荷条件下并联螺旋管内沸腾两相流的动态流量分配及动态传热特性的实验研究，建立相应的计算模型，为新型螺旋管式直流蒸汽发生器的设计、调节与控制策略的制定、安全运行提供技术支持。

Helical tube steam generator is the core equipment for energy transfer in new nuclear reactors. All existing studies on the flow, heat transfer, and flow instabilities of the two-phase flow in the helical tube have focused on special tube types and conditions. The related research results are scattered, and no unified and universal conclusion has been formed. In the special new helical tube steam generator with high temperature difference and high superheat, the boiling two-phase flow heat transfer, pressure drop, flow distribution and flow instabilities between parallel helical tubes all present new characteristics, which requires in-depth studied. In this regard, the experimental studies on the two-phase flow and heat transfer in the helical tube under different geometries are carried out. Based on two-phase flow dynamics analysis, high-precision calculation models for two-phase flow vapor content, resistance and heat transfer in the helical tube are established, as well as the calculation models suitable for predicting the dynamic two-phase flow distribution and flow instabilities between parallel helical tubes in the steam generator. The flow instability spectrum and the predicted correlations for stability boundaries of various oscillations in the helical tube are proposed. An experimental study on the flow distribution and heat transfer characteristics of the two-phase flow in the spiral tube under dynamic variable load conditions is conducted, and the corresponding models are established. The project can provide core technical support for the design, regulation and control strategy, and safe operation of the helical tube steam generator.