核主泵小流量工况下不稳定流动数值模拟

为研究小流量工况下核主泵驼峰现象,通过三维软件Pro/E对核主泵内部流道进行三维造型,基于雷诺时均N-S方程和k-ε湍流模型两方程及SIMPLEC算法,应用计算流体力学软件CFX对核主泵小流量工况进行了定常数值模拟和分析.结果表明：采用定常数值模拟,可以阐明小流量区域的不稳定驼峰现象.泵壳出口位于泵壳的中心,使得沿叶轮旋转方向的主流与出口处的液体发生摩擦和碰撞,造成能量损失,导致内部流场分布不均匀.核主泵对称性结构、叶轮叶片进口和出口复杂旋涡、导叶内复杂的回流以及泵的旋转失速与不稳定驼峰的形成都有密切的联系.核主泵在小流量下运行时,出现不稳定流动,严重时会引起泵的振动.

Numerical analysis on unstable flow of reactor coolant pump under small flow rate condition

For the study on hump phenomenon of an reactor coolant pump, three-dimensional modeling for the pump internal flow was done by Pro/E, and based on the Reynolds - averaged Navier - Stokes equations with the RNG k - ε turbulence model and SIMPLEC algorithm, the flow was calculated using the computational fluid dynamics software CFX. The results show that： the numerical simulation method used is feasible to explain unsteady hump phenomenon of reactor coolant pump under small flow rate conditions. Pump outlet is located in the center of the pump shell, making the mainstream along the direction of rotation friction crashing with the liquid at the outlet, resulting in energy loss and leading to the uneven distribution of the flow field. The symmetric structure of reactor coolant pumps, the complex vortex near inlet and outlet of impeller blades, secondary flow in guide vanes region and rotating stall are closely related to the formation of the hump. The reactor coolant pump running under small flow conditions will cause unstable flow, which can result in severe vibration.