抄録
This paper presents structural design measures to suppress fluid noises of large capacity open motors at their generation stages without any silencers. Interaction noise, which has high peaks at certain frequencies, is largely reduced by as much as 5dB (A) in the overall noise level by nonuniform distribution of the rotor radial vent openings along the rotor circumference. Turbulent noise, which appears in a wide frequency range, is significantly lowered by as much as 6dB (A) in the overall noise level by unaligning the rotor radial ducts with respect to the stator radial ducts by a vent width. These two structural design contribute to reduce the size of large capacity open motors as small as 1/3 compared to the conventional motors.
