1826 遠心送風機発生騒音の能動音源制御

概要

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Based on the detailed investigation of the effective noise source distribution of blade-passing frequency (BPF) noise radiated from a centrifugal blower, active cancellation of noise sources is conducted. The extent of the effective noise sources of fundamental and higher-order BPF lies on the volute-side surface on the scroll relatively apart from each other, i.e., noise source of fundamental BPF exists on the vicinity of the cut off apex, while that of higher-order BPF lies relatively downstream area on the casing scroll. Therefore, simultaneous reduction of both fundamental and higher-order BPF can be possible. In the experiments, piezoelectric actuators are used to oscillate the casing wall directly. Noise level of fundamental and higher-order BPF can be reduced about 15 decibels, and discrete tones are almost disappeared from the power spectra of the blower radiated noise.
2000-07-31