Combining active control and synchrophasing for vibration isolation of a floating raft system: An experimental demonstration

Tiejun Yang,Zhigang Liu,Michael J Brennan,Lei Wu,Xinhui Li,Minggang Zhu

doi:10.1177/1461348420933381

Abstract

Vibration isolation of a floating raft system typically found in a marine application is of concern in this paper. Housed on the raft are electrical motors each driving two counter rotating shafts with eccentric masses attached. An experimental study is described in which vibration transmitted to a large-scale, laboratory-based hull-like structure is attenuated by using three measures. They are, the use of vibration isolators between the raft and the hull-like structure, adjustment of the phase of the electrical supply between the motors to minimize vibration transmitted through the isolators, and the application of an active vibration control system using hydraulic actuators placed in parallel with the isolators. The results show that this combination of measures is extremely effective at reducing the vibration transmission to the hull-like structure, and consequent reduction the sound radiation. It is more effective than the application of any of the vibration control measures applied by themselves.

Highlights

Vibration isolation using passive isolators is widely used in marine applications through different configurations, such as a single-stage, a double-stage, and a floating raft isolation system
This paper has described an experimental study into the vibration control of transmitted vibration from a machinery raft that houses four synchronous machines
As the machines are driven by electrical motors, the phases of the machines were adjusted prior to implementing an active control system to minimize the vibration transmitted to a hull-like structure and suppress the corresponding sound radiation

Summary

Introduction

Vibration isolation using passive isolators is widely used in marine applications through different configurations, such as a single-stage, a double-stage, and a floating raft isolation system. If the machines generating the vibration are electrical, synchrophasing may be an alternative vibration control strategy. The idea behind this can be traced back many years to the control of vibration by adjusting the speed and phase angles of two engines in a steam ship.[13] little attention has been paid to the control the vibration of raft-mounted machinery using this control scheme.[14,15] It has been used to control sound in aircraft cabins[16,17,18] and ducts.[19,20] Recent research on synchrophasing in aircraft has concentrated on active synchrophasing, using microphones and accelerometers positioned throughout the aircraft, together with adaptive

Objectives

Results

Conclusion