钠泵压力脉动特性分析

Analysis of Pressure Pulsation Characteristics of Sodium Pump

为了探究某型钠泵流场压力脉动特性,采用ANSYS CFX软件,选取SST湍流模型,对其在0.6Qn、0.8Qn、1.0Qn和1.4Qn(Qn为设计点流量)工况下进行了非定常数值模拟。数值计算得到的钠泵性能曲线与试验值吻合较好,验证了数值计算模型的准确性。在叶轮和导叶的某一流道分别设置了3个监测点,分析了叶轮和导叶不同位置处的压力脉动规律,并对时域信号进行傅里叶变换,对其进行频域分析。结果表明:从叶轮入口到导叶出口,压力脉动先增大后减小,叶轮出口和导叶入口处压力脉动最大;叶轮流道内压力脉动频率以导叶叶频为主,导叶流道内压力脉动频率以叶轮叶频为主,小流量工况下,低频信号影响较大;导叶出口压力脉动明显比叶轮出口小,但是由于半球形泵壳的束缚,导叶出口处出现了末端回流。通过对钠泵内部的压力脉动分析,可为钠泵的研究和优化设计提供参考。

In order to study the pressure pulsation characteristics of the sodium pump,ANSYS CFX and SST turbulence model are exploited to conduct unsteady numerical simulation calculations under the conditions of 0.6Qn、0.8Qn、1.0Qn and 1.4Qn(Qn is the design point flow).The characteristic curve of the sodium pump agrees well with experimental data,which verifies the correctness of the simulations.Three monitoring points are set in a certain flow channel of impeller and guide vane,respectively,and the pressure pulsation characteristics at different positions of the impeller and the guide vane are analyzed.Fast Fourier Transformation is exploited to process the signals.Results shows that from the inlet of the impeller to the outlet of the guide vane,the pressure pulsation first increases and then decreases,while the pressure pulsation at the outlet of the impeller and the inlet of the vane is larger than that in other areas.Frequency of the pressure pulsation in impeller flow channel is dominated by guide vane blade frequency,while that in guide vane flow channel is dominated by impeller blade frequency.Low frequency signals have a greater impact under low flow conditions.The pressure pulsation at the outlet of the guide vane is significantly smaller than that at the impeller outlet,while the end reflow occurs at the outlet of the guide vane due to the restraint of the hemispherical pump casing.Analysis of pressure pulsation provides guidance for the research and optimum design of the sodium pump.