Abstract
Reducing noise in a low frequency region of 1 kHz or less has become an important problem as a result of emergence of an ultra-high bypass engine in aircraft engines. Therefore, an attempt was made of experimenting and analyzing noise absorption characteristics in low-frequency noises. In the experiment, a low-frequency flow with an air volume of about 3 m{sup 3}/minute was made at a stable operating point of a fan device consisting of moving blades and static blades, with a sound absorbing duct disposed in the forward section. The duct is a 500-mm long steel box with an oblong cross section, in which the top and the bottom parts can move vertically, and a variable air layer was formed between a sound absorbing material (a sheet material made of microfine spherical resin powders solidified to a thickness of 6 mm) and a rigid wall made of iron plate. Noise waves and sound absorption amount were measured on different air layer thicknesses, and analyzed theoretically. As a result, such findings were obtained as: the sound absorption amount is affected by the main stream direction mode of sound pressures in cavity; valleys are formed where the sound absorption amount decreases remarkably in
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Kaneko, K;
Fujii, S;
[1]
Shirasaya, H
[2]
- University of Osaka Prefecture, Osaka (Japan). Faculty of Engineering
- Kawasaki Heavy Industries, Ltd., Tokyo (Japan)
Citation Formats
Kaneko, K, Fujii, S, and Shirasaya, H.
Low-frequency noise reduction of fans using the acoustically treated duct; Kyuon duct ni yoru fan soon no teishuhaiki teigen.
Japan: N. p.,
1994.
Web.
Kaneko, K, Fujii, S, & Shirasaya, H.
Low-frequency noise reduction of fans using the acoustically treated duct; Kyuon duct ni yoru fan soon no teishuhaiki teigen.
Japan.
Kaneko, K, Fujii, S, and Shirasaya, H.
1994.
"Low-frequency noise reduction of fans using the acoustically treated duct; Kyuon duct ni yoru fan soon no teishuhaiki teigen."
Japan.
@misc{etde_52255,
title = {Low-frequency noise reduction of fans using the acoustically treated duct; Kyuon duct ni yoru fan soon no teishuhaiki teigen}
author = {Kaneko, K, Fujii, S, and Shirasaya, H}
abstractNote = {Reducing noise in a low frequency region of 1 kHz or less has become an important problem as a result of emergence of an ultra-high bypass engine in aircraft engines. Therefore, an attempt was made of experimenting and analyzing noise absorption characteristics in low-frequency noises. In the experiment, a low-frequency flow with an air volume of about 3 m{sup 3}/minute was made at a stable operating point of a fan device consisting of moving blades and static blades, with a sound absorbing duct disposed in the forward section. The duct is a 500-mm long steel box with an oblong cross section, in which the top and the bottom parts can move vertically, and a variable air layer was formed between a sound absorbing material (a sheet material made of microfine spherical resin powders solidified to a thickness of 6 mm) and a rigid wall made of iron plate. Noise waves and sound absorption amount were measured on different air layer thicknesses, and analyzed theoretically. As a result, such findings were obtained as: the sound absorption amount is affected by the main stream direction mode of sound pressures in cavity; valleys are formed where the sound absorption amount decreases remarkably in a specific cycle; and peaks are built where the sound absorption amount increases in other regions. 7 refs., 12 figs.}
journal = []
issue = {580}
volume = {60}
journal type = {AC}
place = {Japan}
year = {1994}
month = {Dec}
}
title = {Low-frequency noise reduction of fans using the acoustically treated duct; Kyuon duct ni yoru fan soon no teishuhaiki teigen}
author = {Kaneko, K, Fujii, S, and Shirasaya, H}
abstractNote = {Reducing noise in a low frequency region of 1 kHz or less has become an important problem as a result of emergence of an ultra-high bypass engine in aircraft engines. Therefore, an attempt was made of experimenting and analyzing noise absorption characteristics in low-frequency noises. In the experiment, a low-frequency flow with an air volume of about 3 m{sup 3}/minute was made at a stable operating point of a fan device consisting of moving blades and static blades, with a sound absorbing duct disposed in the forward section. The duct is a 500-mm long steel box with an oblong cross section, in which the top and the bottom parts can move vertically, and a variable air layer was formed between a sound absorbing material (a sheet material made of microfine spherical resin powders solidified to a thickness of 6 mm) and a rigid wall made of iron plate. Noise waves and sound absorption amount were measured on different air layer thicknesses, and analyzed theoretically. As a result, such findings were obtained as: the sound absorption amount is affected by the main stream direction mode of sound pressures in cavity; valleys are formed where the sound absorption amount decreases remarkably in a specific cycle; and peaks are built where the sound absorption amount increases in other regions. 7 refs., 12 figs.}
journal = []
issue = {580}
volume = {60}
journal type = {AC}
place = {Japan}
year = {1994}
month = {Dec}
}