减温减压器的作用是将通过蒸汽排放系统的高温高压蒸汽减温降压，它对核动力装置的稳定运行有着非常重要的作用。采用三维数值模拟的方法，先建立小孔减压模型，对数值计算方法进行研究，通过对计算结果的分析，确定数值模拟的各项参数的选取原则。在保证计算结果的准确性下，得出小孔模型中的出口流量、出口压力以及孔内达到的流动马赫数之间的关系，分析各流量条件下不同孔径、孔长的孔内具体的流动形式，最终得到完整的小孔减压特性。根据设计方案，按照分级建模的思路,建立减温减压器的真实模型,研究真实模型中各级流动总体参数的变化规律，研究表明：真实模型的计算结果同设计方案之间的误差约30.0%，而多级排放和旋涡损失应该是造成误差的主要原因。

The function of the desuperheater and decompressor is to reduce temperature and pressure of the high temperature and high pressure steam passing through the steam discharge system,This function plays a very important role in the stable operation of the nuclear power plant.In this paper,the threedimensional numerical simulation is used and a single hole throttling model is established first.Then the numerical calculation method is studied.Through the analysis of the calculation results,the selection principles of various parameters of the numerical simulation are determined.On the premise of ensuring the accuracy of the calculation results,this paper has obtained the relationship between the outlet flow rate,outlet pressure and the flow Mach number through the single hole throttling model,and then analyzed the specific flow forms in the pore with different hole diameters and lengths under various flow conditions.Finally the complete hole decompression characteristics are obtained.According to the design and the hierarchical modeling,the real models of desuperheater and decompressor are established,and the variations of overall flow parameters at all stages in the real model are investigated,The results show that the calculation error with the real model is about 30.0% compared to the design parameters, and the multistage emissions and the vortex loss should be the main causes of the error.

TK212

国家自然科学基金（51476015）