基于CFD技术的核电站上充泵全流场数值模拟

为研究核电站上充泵内部流动规律,基于计算流体动力学（CFD）技术,采用Reynolds时均N-S方程和标准k-ε湍流模型,压力、速度耦合使用SIMPLEC算法,对1 000 MW核电站离心式上充泵全流场的三维定常湍流进行数值模拟,得到上充泵各级叶轮-导叶内部的速度、静压以及湍动能分布图,并对其内部流动状态进行分析.在数值模拟的基础之上,对4级上充泵样机进行了性能试验,并且换算成12级实型泵的性能,将性能试验结果和模拟性能预测结果进行对比.数值模拟结果表明：在叶轮、导叶间隙处出现局部低压区;叶轮出口和导叶进口交界区域速度分布不均匀,局部区域有逆流和旋涡,造成部分水力损失;叶轮出口和导叶进口处的湍动能较大,且分布极不规律,有较大的能量损失.从数值模拟的结果可以得到上充泵内部流动水力损失严重的区域,为进一步优化上充泵的设计提供参考.数值模拟和试验两者的结果吻合较好,验证了计算模型和换算结果的正确性.

CFD numerical simulation of flow field in charging pump for nuclear power plants

In order to study the internal flow mechanism of the multistage centrifugal charging pump in nuclear power plants,the steady 3D turbulent flow in such a pump in a 1 000 MW nuclear power plant has been simulated numerically by using CFD technique,where the k-ε standard turbulence model and SIMPLEC algorithm were adopted.The velocity,pressure and turbulent kinetic energy distributions in the impeller and diffuser of every stage were obtained;through those variables the internal flow characteristics were analyzed.The results showed that a local low pressure zone appears in the gap between the impeller and the diffuser.An non-uniform velocity distribution and reverse flow pattern,which are related to extra hydraulic losses,present in the region between the impeller outlet and the diffuser inlet.In that region,the turbulent kinetic energy is not only much high but also subject to very non-uniform profile,generating larger energy loss.By means of the numerical simulations the regions with remarked hydraulic loss have been identified.This is quite helpful to optimize the pump design in future.