Experimental Study on Bubble Acoustic Characteristics of Elliptical Nozzles

Cong, Shanhao; Liu, Jingting

doi:10.1051/e3sconf/202129901009

Cited by 3 publications

(2 citation statements)

References 13 publications

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“…Moreover, the phenomenon of almost uniform pressure distribution and non-uniform velocity distribution within the bubble is found, which is basically in accordance with the results of experimental studies on underwater explosive charge performed by Liang [15] and Poplavski [16]. The experimental research on the gas jet generated by underwater detonation employs mostly pressure measurements and high-speed photography combined with particle image velocimetry (PIV) techniques to obtain the pressure oscillation characteristics of the field and the typical phenomena of the bubble evolution, such as bubble expansion, shrinking, and necking [17][18][19].…”

Section: Introductionsupporting

confidence: 82%

Investigation of the Effect of Nozzle on Underwater Detonation Shock Wave and Bubble Pulsation

Wang

Huang

et al. 2022

Energies

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The subject of a gas jet generated by underwater detonation is an important issue in the field of underwater propulsion. The experimental system of underwater detonation is established, which utilizes a high-speed camera to record the morphological changes in bubbles and various pressure sensors to measure the flow field pressure. The effect of nozzles and the pressure of the flow field are analyzed thoroughly. The comparison of the bubble and field pressure shows that the shrinking nozzle increases the peak pressure of the transmitted shock wave generated by underwater detonation compared with that of the straight nozzle. Simultaneously, the water–air mixing phenomenon caused by the gas jet is enhanced. Under the influence of the reflected shock wave and the converging angle of the nozzle, the pulsation process of the bubble is inhibited enormously, which results in the bubble energy being substantially below that of the straight nozzle. The bubble pulsation period is 24.2 ms when the shrinking nozzle is installed, and the pressure of the bubble pulsation is quite small, only 9.8 kPa. On the contrary, the expansion angle increases the velocity of the gas jet, suppressing the water–gas mixing phenomenon while enhancing the bubble pulsation process. The bubble pulsation period is 33.0 ms when the expanding nozzle is equipped, which is larger than the 31.2 ms of the straight nozzle and the bubble pulsation pressure is higher, at 26.1 kPa. Although the bubble energy is increased when the expanding nozzle is installed, thus generating a higher pulsation pressure, the peak pressure and direction of the shock wave are changed in the water.

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Section: Introductionsupporting

confidence: 82%

Investigation of the Effect of Nozzle on Underwater Detonation Shock Wave and Bubble Pulsation

Wang

Huang

et al. 2022

Energies

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“…They found that the turbulence intensity at the air-liquid interface increased considerably with an increase in fluid density, resulting in poorer jet stability. Regarding the noise characteristics of underwater gas jets, the noise from low-speed jets is primarily caused by bubbles [18][19][20][21][22]. However, based on the research conducted by Liu et al [23], who used a large eddy simulation (LES) to analyze the flow structure and noise radiation of underwater supersonic jets, the noise generated by high-speed jets originated primarily from the shockwave structure of the jet.…”

Section: Introductionmentioning

confidence: 99%

A Numerical Simulation of the Underwater Supersonic Gas Jet Evolution and Its Induced Noise

Wang

Zhang

2023

Applied Sciences

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To explore the complex flow field and noise characteristics of underwater high-speed gas jets, the mixture multiphase model, large eddy simulation method, and Ffowcs Williams–Hawking (FW–H) acoustic model were used for simulations, and the numerical methods were validated by the gas jet noise experimental results. The results revealed that during the initial stages, the jet collided with the water surface and created low-pressure high-temperature gas bubbles, accompanied by much high-frequency noise. When the jet reached its maximum length, its impact weakened, the bubble broke, the jet transformed into a conical shape, and the jet noise changed from high- to low-frequency. The pressure fluctuation peaked near the position at which the Mach number reached 1, indicating that the jet was the most unstable at the sonic point. Additionally, at low frequencies, the sound pressure levels between jets with different nozzle pressure ratios were similar, whereas above 400 Hz, under-expanded jets had higher sound pressure levels. This paper provides theoretical guidance for the study of underwater jet noise.

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Experimental study on asymmetric bubbles rising in water: Morphology and acoustic signature

Cong

Song

et al. 2022

Physics of Fluids

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This study develops a three-dimensional imaging system to obtain comprehensive information on asymmetric bubbles formed in five nozzles with exits of the same cross section to examine the relationship between their patterns of flow and their acoustic characteristics. Acoustic signals of the bubbles were recorded by a hydrophone, and were analyzed through filtering and the short-time Fourier transform. The results show that the morphology of the bubbles became complex with increasing aspect ratio of the cross section of the nozzle exit. This complexity was reflected in the shape of the bubbles as well as their manner of detachment and motion. Furthermore, the asymmetry of the bubbles had a significant impact on the sound pressure. Different bubble detachments from five nozzles can lead to different waveforms of sound pressures, viz., “triangle,” “tree,” and “fish.” The differences are proved to be closely associated with the bubbles having different patterns of flow. The work here can be used to identify the patterns of flow of bubbles, reduce noise, and detect failure.

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Experimental Study on Bubble Acoustic Characteristics of Elliptical Nozzles

Cited by 3 publications

References 13 publications

Investigation of the Effect of Nozzle on Underwater Detonation Shock Wave and Bubble Pulsation

Investigation of the Effect of Nozzle on Underwater Detonation Shock Wave and Bubble Pulsation

A Numerical Simulation of the Underwater Supersonic Gas Jet Evolution and Its Induced Noise

Experimental study on asymmetric bubbles rising in water: Morphology and acoustic signature

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