空洞形消音器の減衰量特性におよぼす気流騒音の影響 : 定音圧音源における実験

概要

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The attenuation characteristics of the simple type and insertion tube type expansion chamber mufflers are measured by using the duct system with a constant pressure sound source made of a driver unit at the mean velocity range under 80m/s. The experimental results are summarized as follows. The attenuation values measured for the silencer tested agree fairly well with the theoretical characteristics values calculated by the equivalent acoustical networks of the system, so far as the difference between the acoustic power of the primary sound source and the flow noise generated in the silencers is sufficiently large. But the attenuations go down as the sound pressure levels measured approach those of the calculations. These attenuation drops are remarkable in the region of the frequency at which the acoustical performance required to the silencer becomes high levels. It is possible to prevent these effects of flow noise on the attenuation characteristics, by inserting a tube with a large number of small holes into the chamber.
東海大学の論文