A Novel Axial Vibration Model of Multistage Pump Rotor System with Dynamic Force of Balance Disc
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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.
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.
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.
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.
KeywordsBalance disc Axial dynamic characteristics Transient force model Multistage pump rotor Finite element method (FEM)
List of Symbols
- b1, b2
Radial and axial clearance
- fr, fz, fθ
Body force components in the radial, axial and circumferential direction
Length of shaft element
- l1, l2
Length of radial and axial clearance
- p1, p2, p3
Inlet pressure, inner pressure and outlet pressure of balance disc
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
Kinetic energy of rotor system
Kinetic energy of elastic shaft element
- ur, uz, uθ
Velocity in the radial, axial and circumferential direction
Potential energy of rotor system
Potential energy of elastic shaft element
Shaft mass for length unit
This work was supported by the National Natural Science Foundation of China (Grant No. 51706087), the Project funded by China Postdoctoral Science Foundation (Grant No. 2018M642177), the Zhejiang Postdoctoral Preferential Foundation (Grant No. zj20180009), the Open Research Subject of Key Laboratory of Fluid and Power Machinery (Xihua University), Ministry of Education (Grant No. szjj2019-009), the Key Research and Development Program of Zhenjiang (Grant No. GY2018023) and Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD). The authors also thank Anthony Akurugo Alubokin and Longjie Yu for their help.
Compliance with Ethical Standards
Conflict of Interest
There are no conflicts of interest as declared by the authors.
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