The Prediction of Industrial Fan Sound Power Levels

In this paper, the aerodynamic, mechanical and electromagnetic sources of noise within a fan are considered. The results of measurement are also included and the observed phenomena are described. The concept of fan similarity for the prediction of sound power is described and various proposed similarity laws discussed. It is concluded that there are not universally applicable similarity laws and that there is not a linear relationship between sound power and fan speed, even at a fixed rating point on the fan's characteristic.