scholarly journals Characteristics of aerodynamic sound sources generated by coiled wires in a uniform air-flow

2003 ◽  
Vol 18 (6) ◽  
pp. 759-770 ◽  
Author(s):  
H. Matsumoto ◽  
K. Nishida ◽  
K. Saitoh
Keyword(s):  
Air Flow ◽  
Sound Sources ◽  
Aerodynamic Sound

scholarly journals Characteristics of Aerodynamic Sound Sources Generated by Coiled Wires in a Uniform Air Flow

2002 ◽  
Author(s):  
Hiroki Matsumoto ◽  
Kohshi Nishida ◽  
Ken-ichi Saitoh
Keyword(s):  
Output Power ◽  
Sound Source ◽  
Velocity Fluctuation ◽  
Air Flow ◽  
Source Region ◽  
Wire Diameter ◽  
Outer Diameter ◽  
Sound Sources ◽  
Aerodynamic Sound

This study deals experimentally with aerodynamic sounds generated by coiled wires in a uniform air flow. The coiled wire is the model of the hair dryer’s heater. In the experiment, the effects of the outer diameter D, wire diameter d and spacing between coils s of the coiled wire on the aerodynamic sound have been clarified. The results of frequency analyses of the aerodynamic sounds show that an aeolian sound is generated by the coiled wire, when s/d is larger than 1. And the peak frequencies of aeolian sounds generated by the coiled wires are higher than the ones generated by a cylinder having the same diameter d. To clarify the characteristics of the aerodynamic sound sources, the directivity of the aerodynamic sound generated by the coiled wire has been examined. And the coherent function between the velocity fluctuation around the coiled wire and the aerodynamic sound has been measured. Moreover the band overall value of coherent output power between the sound and the velocity fluctuation has been calculated. This method has clarified the sound source region of the aeolian sound generated by the coiled wire. These results show that the aeolian sound is generated by the arc part of the coiled wire which is located in the upper side of the air flow.

Numerical Study on Air-Reed Instruments With LES

2011 ◽  
Author(s):  
Kin’ya Takahashi ◽  
Masataka Miyamoto ◽  
Yasunori Ito ◽  
Toshiya Takami ◽  
Taizo Kobayashi ◽  
...  
Keyword(s):  
Numerical Study ◽  
Sound Field ◽  
Acoustic Analogy ◽  
Empirical Theory ◽  
Sound Sources ◽  
Aerodynamic Sound ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Semi Empirical ◽  
2D And 3D

The acoustic mechanisms of 2D and 3D edge tones and a 2D small air-reed instrument have been studied numerically with compressible Large Eddy Simulation (LES). Sound frequencies of the 2D and 3D edge tones obtained numerically change with the jet velocity well following Brown’s semi-empirical equation, while that of the 2D air-reed instrument behaves in a different manner and obeys the semi-empirical theory, so called Cremer-Ising-Coltman theory. We have also calculated aerodynamic sound sources for the 2D edge tone and the 2D air-reed instrument relying on Ligthhill’s acoustic analogy and have discussed similarities and differences between them. The sound source of the air-reed instrument is more localized around the open mouth compared with that of the edge tone due to the effect of the strong sound field excited in the resonator.

scholarly journals Experimental visualization of aerodynamic sound sources using parallel phase-shifting interferometry

2020 ◽  
Vol 61 (9) ◽  
Author(s):  
Risako Tanigawa ◽  
Kohei Yatabe ◽  
Yasuhiro Oikawa
Keyword(s):  
Optical Method ◽  
High Speed ◽  
Near Field ◽  
Phase Shifting ◽  
Flat Plates ◽  
Noise Sources ◽  
Sound Sources ◽  
Aerodynamic Sound ◽  
Phase Shifting Interferometry ◽  
Pressure Fields

Abstract Aerodynamic sound is one of the causes of noise in high-speed trains, automobiles, and wind turbines. To investigate the characteristics of aerodynamic sound generation, measurements around the sound sources are required. Aerodynamic sound is typically measured using microphones. However, microphones cannot capture the near-field of aerodynamic sound because they become new noise sources inside the air flow. To observe the aerodynamic sound near-field, we performed two-dimensional visualization of aerodynamic sound using an optical method. The optical method used in this research, parallel phase-shifting interferometry (PPSI), can detect the pressure within the measurement area as variations of the phase of light. PPSI can therefore visualize the pressure fields. We visualized both the sound pressure and flow components of the sound generated by flow around a square cylinder and flat plates. The visualized pressure fields are provided as animations in the online resources. Analysis of the sound and flow component time variations confirmed the correlations between them. Graphic abstract

1009 Analysis of Aerodynamic Sound Sources in Wing Tip Flow and Prediction of Far-field Sound generated from the Flow

2010 ◽  
Vol 2010 (0) ◽  
pp. 277-278
Author(s):  
Kazuaki YAMASARI ◽  
Fabbro NICOLAS ◽  
Masaaki OHNISHI ◽  
Kentaro YATUDUKA ◽  
Chisachi KATO ◽  
...  
Keyword(s):  
Far Field ◽  
Sound Sources ◽  
Aerodynamic Sound ◽  
Wing Tip ◽  
Field Sound
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