自平衡多级泵节流密封的泄漏流动特性

Leakage flow characteristics in throttle clearance of self-balancing multistage centrifugal pump

为研究高扬程大流量自平衡多级泵出水段节流密封的流体介质泄漏特性以及流动机理,建立了3类节流密封的三维数值模型,计算分析了5种径向节流间隙(0.5,0.8,1.0,1.2和1.5 mm)下3类节流密封的泄漏流动、湍动能耗散以及密封流体力等流动特征.研究结果表明:出水段节流密封的泄漏流动特性是密封流体径向缩流比和轴向湍动能耗散率共同作用的结果,径向节流间隙直接影响着径向节流间隙进口处的流体压力和径向缩流比,对节流密封的降压与减速作用显著,而迷宫齿对密封流体的湍动能耗散率的影响较大,膨胀腔体内流体的湍动能耗散率均接近于0,径向节流间隙内流体压力沿轴向方向大致呈现阶梯式下降规律,密封齿能够有效地降低密封流体的压力;转子面密封齿与密封流体的接触以及径向节流间隙增大,是导致第二、三类密封转子面的轴向力显著大于第一类密封的主要原因.

To study the leakage characteristics and flow mechanism of throttling seal in the outlet section of self-balancing multistage pump with high head and large flow rate,a three-dimensional numerical analysis models of three types of throttling seals were established under five radial throttle clearance(0.5,0.8,1.0,1.2 and 1.5 mm).The leakage flow,turbulent kinetic energy dissipation,and seal flow force of the sealed fluid in the throttle seals were calculated and analyzed.The research results indicate that the leakage flow characteristics of the throttle seal are influenced by the radial contraction ratio and axial turbulent kinetic energy dissipation rate.The radial throttle clearance directly affects the fluid pressure and radial contraction ratio at the inlet of the radial throttle clearance.The labyrinth teeth have significant influence on the turbulent kinetic energy dissipation rate,while the turbulent kinetic energy dissipation rate of the fluid in expansion cavity is close to zero.The fluid pressure in the radial throttle clearance generally presents a step wisel decreasing law along the axial direction.Sealing teeth can effectively reduce the pressure of the sealing fluid.Compared with the first type of seal,the contact between the sealing teeth on the rotor face and the sealing fluid,as well as the increase of the radial throttle clearance are the main reasons for the axial force on the rotor face of the second and third type seals.