并联通道内超临界水流动不稳定性的数值模拟研究

超临界水的流动不稳定性特征研究是超临界水冷堆热工水力设计的重点，为进一步获得超临界水流动不稳定性发生的内部机理，采用系统分析程序RELAP5对已有实验本体进行建模，并基于已有超临界水不稳定性实验数据开展了计算方法的验证；系统研究了并联通道内超临界水的流动不稳定性规律，并对比研究了超临界水与亚临界水的不稳定边界。结果表明，超临界水的流动不稳定界限功率随入口温度的增加存在变化拐点；相同入口温度下，随压力上升，不稳定界限功率增加，超临界水相比亚临界气-液两相流具有更好的稳定性；无量纲准则数在超临界条件下具有适用性，超临界水不稳定性变化规律与亚临界水具有相似性。 

Numerical Analysis of Density Wave Instability Phenomena of Supercritical Water in Two Parallel Channels

The flow instability of supercritical water is an important aspect of thermal-hydraulic design of Supercritical Water-cooled Reactor(SCWR). The validated numerical simulation method helps to obtain the internal mechanism of flow instability, a wider instability boundary, and further deepen the understanding of supercritical water flow instability. Based on the experimental data of supercritical water instability that has been carried out, this paper carried out the verification of the calculation method;on this basis, using the system analysis program as a tool, the flow instability phenomena of supercritical water in parallel channels were systematically studied. In this paper, the inflection point of the influence of the supercritical water inlet temperature is obtained;the instable threshold power increase with the increase of the operating pressure at the same inlet temperature and the working fluid under the supercritical condition has better stability characteristics;the suitability of the dimensionless criterion is evaluated under supercritical conditions.