中文摘要：

核主泵内的流动不稳定将会引起严重振动，不利于其安全稳定运行。因此本文基于大涡模拟（LES）数值计算方法对几个典型工况下核主泵内部非稳态流动结构及其压力脉动特性进行全面阐述与关联性分析。研究表明，随着流量的增加，动静干涉作用在导叶出口处逐渐增加；偏工况条件下，导叶出口处压力脉动频谱低频段中均出现复杂激励频率，尤其是靠近出液管附近的导叶出口处。核主泵在偏大流量工况下运行时壳体右侧内部非稳态流动结构相较于壳体左侧更加复杂；在偏小流量工况下运行时壳体底部压力脉动更加剧烈。本文进一步详细描述了核主泵球形壳体内强涡量区的流动结构及其成因，并且发现测点处的压力频谱与涡量频谱有相同的主要激励频率，因此证明核主泵内非定常旋涡流动结构是激励压力脉动的主因之一。

英文摘要：

Flow instability will cause severe vibration in the nuclear reactor coolant pump （RCP）, and it is bad for the safe and stable operation. Thus, thin article is based on large eddy sinmlation （LES） numerical calculation method to study the internal unsteady flow structures and pressure pulsation characteristics and correlation analysis of the RCP under several typical working conditions. Research shows that with the increase of flow rate, the rotor-stator interactions gradually increase ill the diffuser outlet. Under the partial working conditions, several complex frequencies are found in low frequency band of pressure spectrum, especially the diffuser outlet near the discharge nozzle. Tile internal unsteady flow structures ill the right side of spherical casing are more complicated than the left side under the large flow conditions. The pressure fluctuation is more intense at the bottom of the spherical casing under the small flow conditions. Further, the unsteady flow structures and its reasons in high vorticity magnitude region are detailly described in the RCP. It has been found that the vorticity spectra and the pressure spectra almost have the same main excitation frequencies. Therefore, it has been confirmed that for particular vortex shedding of the RCP. regions pressure pulsations are determined by the