超临界压力水管内流动不稳定性的实验研究与数值分析

超临界水冷堆和超（超）临界锅炉能够有效提高主蒸汽参数，对于提高能源利用效率和节能减排具有重要的意义。由于堆芯和蒸发受热面进出口物性参数的剧烈变化，流动不稳定性已经成为影响设备安全运行的关键问题。本项目将搭建能够实现真实压力和温度的超临界水流动不稳定实验系统，通过实验研究获得高热流密度条件下超临界压力水的静态不稳定和动态不稳定的起始点条件及压力、流量、进口温度与节流系数、以及可压缩容积等关键参数的影响规律，掌握流动不稳定的实验方法和测量数据辨识与处理理论。基于燃料放热-传导-对流相互耦合的汽水系统多参数非线性特点，建立跨临界压力的汽水流动不稳定性数学模型，并采用时域方法对控制方程进行求解。对全运行负荷范围内的汽水系统流动不稳定性进行计算分析,揭示超临界压力区流动不稳定性的类型、机理及边界，谋求相应的汽水系统调控策略。该研究可为进一步拓宽设备安全运行与控制的流体动力学基础提供科学依据。

The thermal parameters of main steam can be increased effectively by supercritical water nuclear reactor (SCWR) and boiler (SPB or USPB), and this is very important for the development of energy utilization efficiency, energy conservation, and emission reduction. Due to the drastic fluid thermal physical properties change from the inlet to the outlet of the core or evaporator, flow instability has become a fundamental problem for the safe operation of related equipments. An experimental system of flow instability for supercritical water should be built to achieve the practical pressure and temperature. The threshold of static instability and dynamic instability, and the effects of pressure, flow rate, heat flux, inlet temperature and orifice pressure drop coefficient, and compressible volume on these instabilities inside tubes can be obtained by the experimental study. The experimental methods and theory of measured data identification and processing will be presented in this study. Based on the coupling fuel heat release-conduction-convection of working fluid, the trans-critical and supercritical flow instability model will be developed, and the governing equations can be solved by applying time-domain approach. The numerical analysis on the characteristics of working fluid flow instability in the range of total operation loads will reveal the types, mechanisms, and boundaries of supercritical water flow instability, and the corresponding control strategy of fluid flow system will be presented. The results can provide scientific guidance for the fluid dynamics related to the safe operation and control of SCWR and USPB.