Investigation of noise and vibration within an oil flooded sliding vane rotary air compressor

Abstract

The Sound Power Level and tonal character of the noise generated by all types of machinery is of significant importance to both manufacturer and consumer. The present investigation has analysed all the major sources of noise and vibration within an oil flooded sliding vane compressor mechanism and also considered the effect of the drive motor and cooling fan in relation to overall compressor noise levels. The sliding vane compressor has minimal out of balance and relatively low running speeds and therefore the potential to be a quiet machine. It has been shown that both mechanical vibration sources and aerodynamically generated noise contribute to the radiated noise spectrum in different frequency bands; mechanical vibration sources dominate below 2.5 kHz but in the range between 2.5 kHz and 5 kHz the sources are predominately aerodynamic. The elimination of the sealing arc bore within the compression mechanism to leave a purely circular bore significantly reduced vibration levels. The use of a specially designed reactive silencer reduced the impact that noise, generated at the discharge port, had on the compressor shell. Finally the cooling fan was identified as the major noise source and recommendations are made for its redesign.