scholarly journals Study on measurement of sound attenuation coefficient in bubble wake by pool

2020 ◽  
Vol 206 ◽  
pp. 03013
Author(s):  
Jing Han ◽  
Shuai Lv ◽  
Zhongpeng Wu ◽  
Mingwei Zhang ◽  
Jin Bai
Keyword(s):  
Attenuation Coefficient ◽  
Bubble Size ◽  
Sound Attenuation ◽  
Signal Frequency ◽  
Sound Waves ◽  
Air Inlet ◽  
Stimulation Tests ◽  
Measurement Experiment ◽  
Small Bubbles ◽  
Attenuation Characteristics

In this paper, bubbles are generated by controlling the air inlet volume of the ceramic tube array with a gas divider valve. Stimulation tests of sound attenuation characteristics of the wake of bubbles in a laboratory pool are performed. A measurement experiment of sound attenuation coefficient was carried out in the case of still water and bubbles with different particle sizes. The signal frequency is 20-200kHz. Through experimental research, it is found that the existence of bubbles makes the sound attenuation coefficient significantly larger. And the attenuation coefficient is related to the frequency of the sound waves and the size of the bubbles. At the same frequency, the larger the bubble size , the larger the attenuation coefficient will be. When the bubble size is constant, the attenuation of the acoustic signal in small bubbles will change greatly below 50kHz. Above 50kHz, the attenuation coefficient changes relatively smoothly and the fluctuation is small. In the case of medium and large bubbles, the fluctuation of the attenuation coefficient becomes larger than that in the small bubbles. Finally, the theoretically calculated sound attenuation coefficient is compared with the experimentally measured results. And the change trends of the two results are basically the same.

A MEASUREMENT OF ULTRASONIC ATTENUATION COEFFICIENT BY FREQUENCY RESPONSE IN STEELS WITH DIFFERENT GRAIN SIZES

2003 ◽  
Vol 26 (4) ◽  
pp. 389-402
Author(s):  
Kyung-Cho Kim
Keyword(s):  
Frequency Response ◽  
Attenuation Coefficient ◽  
Evaluation Method ◽  
Ultrasonic Attenuation ◽  
Wave Length ◽  
Structural Behavior ◽  
Response Property ◽  
Sound Waves ◽  
Grain Sizes ◽  
Plate Specimen

A new evaluation method of ultrasonic attenuation in materials is proposed based on the frequency response property of the material evaluated by employing the sound impulse of a wide frequency band. Borrowing from ordinary system theory, the material to be tested is considered to have a characteristic impulse response, representing its micro-structural non-uniformities and thus resulting in the sound attenuation of the material. The concept is resumed as an attenuation system that simulates the material’s micro-structural behavior. Experimental results on a series of specimens, having different grain sizes but all made of a single austenitic stainless steel, showed that the attenuation could properly be evaluated from a single bottom echo in a plate specimen. The attenuation coefficient α, was corrlated in this case to the grain size, D, by the equation, αD=H(πD/λ)n, where λ is wave length and H and n are constants. It was also shown that the micro structural change of materials could be evaluated by the energy loss of sound waves passing through the attenuation systems.

Giant Quantum Attenuation of Sound Waves in Bismuth. II. Line Shape of the Attenuation Coefficient

1970 ◽  
Vol 28 (5) ◽  
pp. 1211-1221 ◽  
Author(s):  
Yasukuni Matsumoto ◽  
Takeshi Sakai ◽  
Shōichi Mase
Keyword(s):  
Attenuation Coefficient ◽  
Line Shape ◽  
Sound Waves

259. Determining Sound Attenuation Characteristics of HPDS Exposed to Impulse Noise

2005 ◽  
Author(s):  
D. Carpenter ◽  
P. Parrish ◽  
D. DeCamp ◽  
S. Purdy ◽  
I. Rybczynski ◽  
...  
Keyword(s):  
Impulse Noise ◽  
Sound Attenuation ◽  
Attenuation Characteristics

scholarly journals Modeling of inclusion removal in a tundish by gas bubbling

2021 ◽  
Author(s):  
John Patrick Rogler
Keyword(s):  
Bubble Size ◽  
Physical Modeling ◽  
Gas Flow ◽  
Separation Efficiency ◽  
Bubble Formation ◽  
Particle Separation ◽  
Contact Angles ◽  
Inclusion Removal ◽  
Gas Bubbling ◽  
Small Bubbles

Inclusion removal from liquid steel by attachment to rising gas bubbles has been reviewed. A mathematical model of inclusion removal by gas bubbling in a tundish has been developed and it is found that minimization of bubble size is critical to enhance removal. However, small bubble formation in a tundish may be problematic as bubble size is controlled by high contact angles between liquid metal and bubble orifice materials. A physical modeling technique has been developed to simulate inclusion removal by tundish bubbling. The influence of a floating particle sink, a flow pattern modifying impact pad, and a bubbler, on particle separation was examined. The influence of gas flow rate, tundish residence time, particle size and bubble size was also examined. Physical modeling confirms that particle separation by gas bubbling in a tundish can be efficient at enhancing inclusion removal. It was also confirmed that relatively small bubbles (<1mm in diameter) are required for maximum separation efficiency.

scholarly journals Fluidic Generator Of Microbubbles – Oscillator With Gas Flow Reversal For A Part Of Period

2015 ◽  
Vol 9 (4) ◽  
pp. 195-203
Author(s):  
Václav Tesař
Keyword(s):  
Bubble Size ◽  
High Speed ◽  
Gas Flow ◽  
Oscillation Period ◽  
Large Bubble ◽  
High Speed Camera ◽  
Fluidic Oscillator ◽  
Fluidic Device ◽  
Working Distance ◽  
Small Bubbles

Abstract Paper presents a fluidic device developed for generation of small (less than 1 mm in diameter) microbubbles in a liquid from gas passing gas through small passages. Until now the bubbles are larger than the size of aerator passage exits so that making the passages smaller did not result in obtaining the desirable microbubbles. Analysis of high-speed camera images (obtained with a special lens of large working distance) have shown show that the large bubble size is caused by slow ascent motion of very small bubbles so that they get into mutual contact and grow by conjunction. The solution is to pulsate the supplied gas flow by a no-moving-part fluidic oscillator. The generated small bubble is moved back into the aerator passage where it is for a part of oscillation period protected from the conjunction with other, previously generated microbubbles.

Attenuation and dispersion of sound in bubbly fluids via the Kramers—Kronig relations

1990 ◽  
Vol 211 ◽  
pp. 61-72 ◽  
Author(s):  
S. Temkin
Keyword(s):  
Attenuation Coefficient ◽  
Acoustic Waves ◽  
Sound Propagation ◽  
Phase Speed ◽  
Order Estimate ◽  
Sound Waves ◽  
Bubble Liquid ◽  
Bubbly Fluids ◽  
Speed Of Propagation ◽  
Additional Support

Sound propagation in a dilute bubble–liquid mixture is studied by means of the Kramers–Kronig relationships, which relate the real and imaginary parts of the general susceptibility of a linear medium. These relationships are adopted for the case of acoustic waves, where they become coupled integral equations. A simple but approximate procedure is used to obtain from these equations the phase speed of sound waves for the case when the attenuation coefficient is independently known. The procedure can be used to obtain the speed of propagation of sound waves in acoustic media having internal dissipation, but is here applied only to fluids containing radially pulsating bubbles. Approximate results for the speed of propagation and for the attenuation per wavelength are obtained for this case on the basis of a first-order estimate for the attenuation coefficient. These results are the same as those derived previously on the basis of model equations for bubbly liquids. They therefore provide additional support for those equations, while indicating some of their limitations.

Sign in / Sign up

Export Citation Format

Share Document