Results 211 to 220 of about 34,975 (261)
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The Journal of the Acoustical Society of America, 1953
Using the apparatus described by Reynolds, Wilson, and Beranek, measurements were made of the acoustic power in watts in twenty-four bands each one-third octave wide for three vaneaxial-type and two centrifugal-type fans of grades sizes. Formulas were derived empirically, enabling the computation of the over-all acoustic power of the noise for the ...
C. E. Peistrup, J. E. Wesler
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Using the apparatus described by Reynolds, Wilson, and Beranek, measurements were made of the acoustic power in watts in twenty-four bands each one-third octave wide for three vaneaxial-type and two centrifugal-type fans of grades sizes. Formulas were derived empirically, enabling the computation of the over-all acoustic power of the noise for the ...
C. E. Peistrup, J. E. Wesler
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The Journal of the Acoustical Society of America, 1955
Extensions of earlier studies [J. Acoust. Soc. Am. 26, No. 2(1953)] on ventilation system noise are reported. It is shown here that in properly engineered ventilation systems the over-all sound power level in decibels re 1013a watt is related to the horsepower rating of the fan motor by the formula: PWL = 100+10 1og10hp.
Leo L. Beranek +2 more
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Extensions of earlier studies [J. Acoust. Soc. Am. 26, No. 2(1953)] on ventilation system noise are reported. It is shown here that in properly engineered ventilation systems the over-all sound power level in decibels re 1013a watt is related to the horsepower rating of the fan motor by the formula: PWL = 100+10 1og10hp.
Leo L. Beranek +2 more
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Journal of Sound and Vibration, 1971
Abstract Helicopter rotor noise theories are used to determine the noise of subsonic fans produced solely by the rotor, which results from aerodynamic intake flow distortions. Extensions to the theories allow for both stationary, phase-related distortions and distortions which vary randomly with time and may therefore be considered to rotate with ...
B. Barry, C.J. Moore
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Abstract Helicopter rotor noise theories are used to determine the noise of subsonic fans produced solely by the rotor, which results from aerodynamic intake flow distortions. Extensions to the theories allow for both stationary, phase-related distortions and distortions which vary randomly with time and may therefore be considered to rotate with ...
B. Barry, C.J. Moore
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Noise Notes, 2000
The cause of high noise generated by a table fan has been investigated. The noise source was identified by sound intensity mapping and frequency analysis of noise signal. The base of the fan stand was radiating high noise. The cause of this noise was found to be due to the resonance of fan stand.
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The cause of high noise generated by a table fan has been investigated. The noise source was identified by sound intensity mapping and frequency analysis of noise signal. The base of the fan stand was radiating high noise. The cause of this noise was found to be due to the resonance of fan stand.
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Passive Noise Reduction for a Contra-Rotating Fan
Volume 1A: Aircraft Engine; Fans and Blowers, 2014There has been renewed interest in the contra-rotating (CR) fan configuration in aviation and other applications where size and weight are important design factors. Contra-rotation recovers swirl energy compared with the single-rotor design, but this advantage is not fully harnessed due to, perhaps, the issue of noise. This study explores passive noise
Wang, C, Huang, L
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Journal of Thermal Science, 2008
In the wake-rotor interaction fan noise, a number of the interacting modes at the blade passing frequency (BPF) and its harmonics are generated which are prescribed by the number of stator and rotor blades etc. In the present study, the dominant mode is tried to be suppressed by the secondary sound from the loudspeaker actuators.
Nobuhiko Yamasaki, Hirotoshi Tajima
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In the wake-rotor interaction fan noise, a number of the interacting modes at the blade passing frequency (BPF) and its harmonics are generated which are prescribed by the number of stator and rotor blades etc. In the present study, the dominant mode is tried to be suppressed by the secondary sound from the loudspeaker actuators.
Nobuhiko Yamasaki, Hirotoshi Tajima
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The Journal of the Acoustical Society of America, 1993
A gas turbine engine rotor assembly such as a fan or compressor includes a plurality of rotor blades spaced axially from a plurality of stator vanes inside an annular duct. The number of vanes is selected for a predetermined number of blades for obtaining substantially equal values of a cut-off ratio for at least two blade passing frequency harmonics ...
Phillip R. Gliebe, Patrick Y. S. Ho
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A gas turbine engine rotor assembly such as a fan or compressor includes a plurality of rotor blades spaced axially from a plurality of stator vanes inside an annular duct. The number of vanes is selected for a predetermined number of blades for obtaining substantially equal values of a cut-off ratio for at least two blade passing frequency harmonics ...
Phillip R. Gliebe, Patrick Y. S. Ho
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The Journal of the Acoustical Society of America, 1995
An axial flow fan includes blades mounted on a hub and extending radially outward to a shroud disposed around the hub. Pairs of stators are connected to the shroud at positions angularly spaced about the inner periphery of the shroud. Each pair of stators includes a trailing stator angularly spaced from a leading stator by a distance related to the ...
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An axial flow fan includes blades mounted on a hub and extending radially outward to a shroud disposed around the hub. Pairs of stators are connected to the shroud at positions angularly spaced about the inner periphery of the shroud. Each pair of stators includes a trailing stator angularly spaced from a leading stator by a distance related to the ...
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The Journal of the Acoustical Society of America, 1981
A fan for moving a gaseous fluid, e.g., air, is described in which the high audible frequency noise resulting from the phenomenon occurring at the trailing edges of the blades, known as vortex shedding, is reduced. This is accomplished by notching an edge of each of the blades so that the pattern of vortices leaving the blade, which causes the noise ...
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A fan for moving a gaseous fluid, e.g., air, is described in which the high audible frequency noise resulting from the phenomenon occurring at the trailing edges of the blades, known as vortex shedding, is reduced. This is accomplished by notching an edge of each of the blades so that the pattern of vortices leaving the blade, which causes the noise ...
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Fan and compressor noise attenuation
The Journal of the Acoustical Society of America, 2010The present invention is a noise attenuation system (40) and related method for suppressing noise having a primary tone generated by a jet engine (20). An exciting sound wave generator (40) is positioned within the nacelle (22) of the jet engine at its inlet (26) to generate an exciting sound wave having a primary frequency generally different from a ...
Man-Chun Tse, André LeBlanc
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