Vibration in a Multistage Centrifugal Pump under Varied Conditions

Ling Bai,Ling Zhou,Qinglong Pang,Daoxing Ye,Xiaoping Jiang

doi:10.1155/2019/2057031

Abstract

Multistage pumps are intended to improve designs with low-vibration and -noise features as the industry applications increase the technical requirements. In this frame, it becomes really important to fully understand the vibration patterns of these kinds of complex machines. In this study, a vibration test bench was established to examine the vibration and stability of a cantilever multistage centrifugal pump under different flow rates. The vibration spectrum diagrams for the inlet and outlet sections and the pump body were evaluated under varied flow conditions. Results showed the effects of operational conditions on the vibration of the cantilever multistage centrifugal pump. Vibration velocity was primarily caused by mass unbalance at the shut-off flow rate point. Under different flow conditions, the blade passing frequency (BPF) and two times the blade passing frequency (2BPF) were the main excitation frequencies. The vibration frequency of the final pump body remained at the BPF under different flow conditions due to the contact with the outlet section. The major type of vibration frequency for the inlet and outlet was high frequency.

Highlights

As an important device used for energy conversion and fluid transportation, multistage centrifugal pumps are widely used in agriculture and industry [1,2,3]
E blade passing frequency (BPF) fbp is the harmonics of shaft frequency fs, which can be calculated through the impeller blade number z1, as fbp z1 and fs 373.3 Hz
Tests were performed under different flow conditions, including the shut-off flow rate point (0Qdes), design flow rate point (1.0Qdes), and overloading flow rate point (1.5Qdes). e vibration spectra were analyzed to assess the vibration state of the pump [18, 19]

Summary

Introduction

As an important device used for energy conversion and fluid transportation, multistage centrifugal pumps are widely used in agriculture and industry [1,2,3]. E vibration spectrum analysis at the inlet pipe and inlet cavity showed that the dominant frequency at the pump inlet was two times the BPF (2BPF), with larger amplitude vibration under the low flow condition. At the design flow rate, the peak value appeared at two times the blade frequency of the third stage and reached 2.24 mm/s.

Results

Conclusion