A Novel Axial Vibration Model of Multistage Pump Rotor System with Dynamic Force of Balance Disc
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ORIGINAL PAPER
A Novel Axial Vibration Model of Multistage Pump Rotor System with Dynamic Force of Balance Disc Wenjie Zhou1 · Yuhua Cao1 · Ning Zhang1,2 · Bo Gao1 · Ning Qiu3 · Weibin Zhang4 Received: 13 June 2019 / Revised: 8 July 2019 / Accepted: 30 July 2019 © Krishtel eMaging Solutions Private Limited 2019
Abstract Purpose In this paper, a novel axial dynamic model including the transient force of balance disc is proposed to predict the vibration characteristics of multistage pump rotor system. Methods To obtain the dynamic force, the rotating effect of the rotor system is considered and the Navier–Stokes equations are further simplified on the basis of the geometric structure and inner flow characteristic of the balance disc. In addition, based on finite element method and matrix operation, a novel axial motion model of rotor system is established. The efficient Newmark method is applied to describe the dynamic response of the coupled rotor system. Results The pressure distribution in axial clearance and the corresponding dynamic force present obvious nonlinear reduction as the axial gap increases from 0.2 mm to 1 mm. The inner chamber pressure is more sensitive to the inlet pressure than the rotating speed, especially when the axial gap is 0.2 mm. Moreover, the axial steady amplitude of the rotor system is directly proportional to the rotating speed and initial axial gap, while it is inversely proportional to the outer radius of the balance disc. In addition, the vibration frequencies for axial vibration are multiple even when the motion of the rotor system is regularly reciprocating. Conclusions The transient force of the balance disc needs to be considered in the calculation of axial rotor dynamics for the multistage pump. The calculated results can provide references for the design of the balance disc and an axial vibration model of the multistage pump rotor system. Keywords Balance disc · Axial dynamic characteristics · Transient force model · Multistage pump rotor · Finite element method (FEM) List of Symbols A Cross-sectional area b1, b2 Radial and axial clearance E Young’s modulus fr, fz, fθ Body force components in the radial, axial and circumferential direction l Length of shaft element l1, l2 Length of radial and axial clearance * Wenjie Zhou [email protected] 1
School of Energy and Power Engineering, Jiangsu University, Zhenjiang 212013, China
2
Mechanical Engineering Department, University College London, London WC1E 7JE, UK
3
Research Center of Fluid Machinery Engineering and Technology, Jiangsu University, Zhenjiang 212013, China
4
Key Laboratory of Fluid and Power Machinery, Ministry of Education, Xihua University, Chengdu 610039, China
p Pressure p1, p2, p3 Inlet pressure, inner pressure and outlet pressure of balance disc Qbd Total axial force of balance disc q1, q2 Flux in radial and axial clearance r1, r2 Inner radius and outer radius of radial clearance r3, r4 Inner radius and outer radius of axial clearance T Kinetic energy of rotor system T
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