Calculation And Analysis Based On The Internal Flow Field Simulation On Critical Rotational Speeds Of The Centrifugal Pump Rotors

Nowadays, the power and speed of the pump rotor is higher and higher, in the process of operation, will inevitably across the first-order even two or three first-order critical speed and multistage pumps in this aspect of the rotor, particularly prominent performance by the influence of the critical speed, in order to guarantee the multistage centrifugal pump rotor smooth running, avoid the near its critical speed and influence produced when resonance, design of the pump life in its work to accurately calculate the critical speed conditions, namely "wet" condition of the critical speed. Calculation of the rotor speed is used to transfer matrix method and finite element method, the finite element method to calculate.Based on a retrofit multistage centrifugal pump is mainly model, clear of the whole flow CFD technology start-up stage model of three-dimensional flow field transient numerical simulation, the comparative study of fluid-solid coupling convection field simulation results, the influence of prediction in start-up stage of multi-level pump impeller performance curves, the guide vane, and speed and pressure distribution, captured in the pump start-up process flows and special to lay the foundation of the critical speed calculation, For immersion rotor, fluid-solid coupling effect not only influence on the flow field and the critical speed also obvious effect, the paper through the establishment of multistage pumps, rotor entity model of rotor fluid-solid coupling and on the modal analysis, discusses the fluid-structure coupling effect and softening effect on the critical speed, This compared with finite element method, deng klein method in calculating under rigid rotor supported first-order critical speed, using numerical entity and spring element finite element model are discussed, the number of impeller lumisizer bearing stiffness and natural frequency of the rotor, and calculated the rotor in different speeds "wet" critical speed. Calculation results show that:1) Numerical simulation of the design condition forecasting performance and the experimental results, the start of the various stages of reflects in different speeds multistage centrifugal pump internal flow state.2) Fluid-solid coupling effect obviously decrease the rotor speed, and with the critical role of speed increased obviously.3) Influence critical speed factors stiffness obviously, accurately, reasonably determine the simplified supporting supporting the stiffness and damping of the matrix is accurate calculation speed.4) Because of the rotor "wet" the fluid-structure coupling effect, in the interface coupled vibrate, relative to the "normal" dry the critical speed have very big difference.Multistage centrifugal pump rotor in "wet" critical speed of calculation, takes into account of various factors and various theories, including traditional rotor dynamics and hydrodynamic lubrication theory and the seal of the dynamics of the knowledge, is a very complicated process, the calculation results for future research, and provides reference for the multistage centrifugal pump rotor structure provides the basis for checking.