为了研究离心泵叶轮内部周期性非定常流动结构，基于POD方法，从能量、时间和空间3个方面对叶轮内部压力场进行分析，研究其非定常流动结构随着流量变化的发展规律。结果表明：叶轮压力场前5阶POD模态的能量占总能量的90%左右；随着流量的降低，离散频率分别为St0.23和St0.19的两种非定常流动结构开始在叶轮入口出现，且与回流区吻合；在流量处于0.8Q Des时，特征频率为St0.23在2~5阶POD能量占比较大，且强度沿着前盖板至轮毂方向逐渐降低；在流量处于0.7 Q Des时，特征频率为St0.23的非受迫周期性流动结构的能量占比降低。由于动静干涉的影响，轴频StR与特征频率St0.23的线性频率St0.19能量强度增加，在流场中占据主导地位，且特征频率为St0.19的流动结构在靠近中截面偏前盖板的能量强度最大，并向两边逐渐降低。

In order to better study the inner periodic unsteady flow structure of the centrifugal pump impeller, the pressure field in the impeller was analyzed based on the POD method from three aspects of energy,time and space to study the development law of the unsteady flow structures with the changes of flow rate.The results show that the energy of the first 5 order POD modes of the impeller pressure field accounts for about 90% of the total energy.As the flow rate decreases, two unsteady flow structures with discrete frequencies of St0.23 and St0.19 begin to appear at the impeller inlet,which is consistent with the backflow zone.When the flow rate is 0.8 Q Des,the energy proportion of characteristic frequency of St0.23 is significant at 2order to 5order POD modes,and the intensity gradually decreases along the direction from the front cover plate to the hub.When the flow rate is at 0.7Q Des,the energy proportion of the nonforced periodic flow structure with the characteristic frequency St0.23 decreases.Due to the influence of dynamic and static interference,the energy intensity of the axial frequency St R and the linear frequency St0.19 of the characteristic frequency St0.23 increases, which occupies a dominant position in the flow field.The flow structure with the characteristic frequency St0.19 has the largest energy intensity near the middle section and the front cover plate, and gradually decreases to both sides.

TH311

国家自然科学基金资助项目（51976125）；国家重点研发项目课题（2017YFC0806604）