Comparison of vibration and acoustic responses in a rotary machine balancing process

Abstract

Balancing a rotating machine is a vital step towards ensuring it will operate reliably and safely. To achieve this condition monitoring is an important aspect for early faulty detection and it can also result in the improvement of the operational continuity and equipment safety. Imbalance itself, is a common problem in rotating machinery and it can lead to poor or even dangerous vibration levels. And, for example, it is also well known that misalignment can lead to bearing defects. So, in order to overcome these problems many balancing techniques have been developed that are largely based on measured vibration data using accelerometers attached to the faulty device. The three-point method is well known as a basic phase-less technique; this method has been used for balancing equipment and is widely regarded as an industry standard technique. In this work we avoid placing sensors on the device under investigation. This is achieved by utilizing a microphone method located in the nearfield of the investigated device. By comparing the traditional vibration technique with the acoustic contact-less method we can demonstrate the method’s remarkable accuracy. Finally, the experimental results show that there is a similar trend between both the vibration and acoustical responses of the machine, and it is proven that it is possible to balance a rotating machine by just utilizing the acoustical response. This is a contactless method and an innovation in machine-dynamics condition monitoring.