EFFECTS OF BLADE DESIGN ON CENTRIFUGAL FAN NOISE AND PERFORMANCE

This paper presents a mathematical model, based on dimensional analysis, of the sound power level generated by any type of aerodynamic noise source, The model is applied to evaluate the effect of blade design on the acoustical performance of centrifugal fans, The theoretical acceleration of the airflow through the channels between the blades is calculated from the equations for un-separated flow, Large negative flow accelerations are indicative of flow separations, Blade shapes that had substantial negative acceleration caused large increases in the wideband sound power level as a result of flow separation, while increasing the aerodynamic losses only moderately. (C) 1995 Institute of Noise Control Engineering.