The Noise Reduction of Thin Blade Propeller Fans

Abstract

An experimental investigation is carried out on the noise reduction of thin blade propeller fan. The center line of the cord of the circular blade inclines toward the inlet direction, and, at the same time, the rotative direction. The effect on the specific noise level is determined for the inclination angle toward the inlet direction (IATID). The most suitable angle for the noise reduction was found for IATID. The specific noise level in free air decreases as IATID increases. When the fan operates between the free air point and the so-called unsteady point of the characteristic, the specific noise level is the lowest at an IATID of 22.5°.