Australian Acoustical Society 1 Correlation of pump efficiency and shaft torsional vibra- tion using torsional laser vibrometry

The extensive use of centrifugal pumps in mining, potable water supply and sanitary installations potentially present an opportunity for energy savings through pump efficiency monitoring. Pumping units in these applications typically incorporate a flexible coupling between the motor and the pump. This coupling permits some shaft misalignment and provides vibration isolation. It is however unknown how significant torsional vibration is between the motor output and the impeller input. Changes in shaft torsional vibration could be a result of variations in the impeller’s torque due to hydrodynamic loading, which may indicate the pump’s efficiency. This paper presents a preliminary experimental study into the shaft torsional vibration on each side of the coupling of a centrifugal pump. This is achieved using a non-contact technique involving two torsional laser vibrometers. In addition to providing a correlation to pump effi-ciency, the method also permits the investigation of impeller angular velocity frequency content and these aspects are discussed in the context of current state-of-the-art in monitoring of pump’s performance