A Velocity Parameter for the Correlation of Axial Fan Noise

An aerodynamic parameter is proposed to relate subsonic axial fan noise to the fundamental flow behavior in the blade row of the fan. This parameter is the peak or maximum blade surface velocity in the rotating reference frame and includes, either explicitly or implicitly, the influence of tip speed, volume flow rate, pressure rise, shaft horsepower and efficiency. Correlation of the noise associated with a very broad range of axial fans—ranging from very lightly loaded household fans to high-speed, high-pressure industrial fans and aircraft propulsion fans—yields good agreement and collapse of data when compared to currently-used correlation methods. Use of this parameter, rather than those based on overall performance, allows trade-off studies to be made within a given performance requirement so that a minimum noise configuration may be designed or selected.