In:
The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 133, No. 5_Supplement ( 2013-05-01), p. 3363-3363
Abstract:
As a countermeasure to reduce exhaust gas pulsation noise in a wide frequency range, the exhaust system employs expansion, resonance and sound absorbing structures with perforated pipes. However, whistle noise is generated near holes under some conditions. In straight-through-type mufflers, sound absorbing materials covering punching holes can suppress whistle noise generation. On the other hand, in the expansion-cavity-type muffler, which has inlet and outlet insertion pipes, effective countermeasures have not been clarified yet. The purpose of this study is to improve understanding of whistle noise generation mechanism in mufflers with perforated pipes. First, we measured sound pressure of whistle noise radiating from a straight-through-type sub-muffler with a perforated pipe with steady flow. Results show that the frequency of predominant whistle noise became higher stepwisely with increasing the flow velocity and was higher with smaller hole diameter. Strouhal number based on the hole diameter, the frequency of predominant whistle noise and flow velocity existed within a certain range while the hole diameter and flow velocity were varied. Next, we measured the sound pressure of whistle noise radiating from an expansion-cavity-type main muffler with a perforated pipe. The whistle noise generation is discussed in comparison with that for the sub-muffler.
Type of Medium:
Online Resource
ISSN:
0001-4966
,
1520-8524
Language:
English
Publisher:
Acoustical Society of America (ASA)
Publication Date:
2013
detail.hit.zdb_id:
1461063-2
Bookmarklink
