Bubble dynamics and pressure field characteristics of underwater detonation gas jet generated by a detonation tube

Liu, Wei; Li, Ning; Wang, Chunsheng; Huang, Xiaolong; Kang, Yang

doi:10.1063/5.0029729

Cited by 20 publications

(5 citation statements)

References 40 publications

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“…The flow rate and direction of the electrolyte affect the movement and detachment of bubbles in the electrolyte. Higher flow rates promote bubble detachment, while lower flow rates may lead to bubble retention and aggregation [76,77]. In summary, bubble detachment is affected by a variety of factors, including electrode surface properties, electrolyte concentration, current density, bubble size and morphology, and flow conditions.…”

Section: Factors Influencing Bubble Detachmentmentioning

confidence: 99%

Bubbles Management for Enhanced Catalytic Water Splitting Performance

Zhang,

Gu,

Wang

et al. 2024

Catalysts

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Water splitting is widely acknowledged as an efficient method for hydrogen production. In recent years, significant research efforts have been directed towards developing cost-effective electrocatalysts. However, the management of bubbles formed on the electrode surface during electrolysis has been largely overlooked. These bubbles can impede the active sites, resulting in decreased catalytic performance and stability, especially at high current densities. Consequently, this impediment affects the energy conversion efficiency of water splitting. To address these challenges, this review offers a comprehensive overview of advanced strategies aimed at improving catalytic performance and mitigating the obstructive effects of bubbles in water splitting. These strategies primarily involve the utilization of experimental apparatus to observe bubble-growth behavior, encompassing nucleation, growth, and detachment stages. Moreover, the review examines factors influencing bubble formation, considering both mechanical behaviors and internal factors. Additionally, the design of efficient water-splitting catalysts is discussed, focusing on modifying electrode-surface characteristics. Finally, the review concludes by summarizing the potential of bubble management in large-scale industrial hydrogen production and identifying future directions for achieving efficient hydrogen production.

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Section: Factors Influencing Bubble Detachmentmentioning

confidence: 99%

Bubbles Management for Enhanced Catalytic Water Splitting Performance

Zhang,

Gu,

Wang

et al. 2024

Catalysts

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“…Thereafter, a larger bubble with a diameter of d ≈3.5 mm exploded with a time delay (frame 6), despite it being subjected to shock compression earlier, being somewhat upstream with respect to the two bubbles that exploded earlier. Furthermore, this bubble expanded (frame 7), shrank again (frame 8) and expanded again (frames 9-11), taking the shape of a parachute (frames 12-14), and then broke up into small fragments (frames [15][16][17][18][19][20]. The processing of video records made it possible to gain information on the shockinduced motion of individual bubbles behind the traveling SW.…”

Section: Single Shock Wave Propagation In Bubbly Watermentioning

confidence: 99%

“…The diverging nozzle was shown to suppress water-gas mixing, increase the gas jet velocity, and enhance the bubble pulsation process. High-speed photography, digital particle image velocimetry, underwater pressure field measurements, and CFD calculations were used in [19,20] to study the two-phase flow nearby the open end of the detonation tube submerged in water. Stoichiometric explosive mixtures of methane, hydrogen, and acetylene with oxygen were detonated in the tube under the same fill conditions.…”

Section: Introductionmentioning

confidence: 99%

Interaction of Shock Waves with Water Saturated by Nonreacting or Reacting Gas Bubbles

et al. 2022

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A compressible medium represented by pure water saturated by small nonreactive or reactive gas bubbles can be used for generating a propulsive force in large-, medium-, and small-scale thrusters referred to as a pulsed detonation hydroramjet (PDH), which is a novel device for underwater propulsion. The PDH thrust is produced due to the acceleration of bubbly water (BW) in a water guide by periodic shock waves (SWs) and product gas jets generated by pulsed detonations of a fuel–oxidizer mixture. Theoretically, the PDH thrust is proportional to the operation frequency, which depends on both the SW velocity in BW and pulsed detonation frequency. The studies reported in this manuscript were aimed at exploring two possible directions of the improvement of thruster performances, namely, (1) the replacement of chemically nonreacting gas bubbles by chemically reactive ones, and (2) the increase in the pulsed detonation frequency from tens of hertz to some kilohertz. To better understand the SW-to-BW momentum transfer, the interaction of a single SW and a high-frequency (≈7 kHz) sequence of three SWs with chemically inert or active BW containing bubbles of air or stoichiometric acetylene–oxygen mixture was studied experimentally. Single SWs and SW packages were generated by burning or detonating a gaseous stoichiometric acetylene–oxygen or propane–oxygen mixture and transmitting the arising SWs to BW. The initial volume fraction of gas in BW was varied from 2% to 16% with gas bubbles 1.5–4 mm in diameter. The propagation velocity of SWs in BW ranged from 40 to 580 m/s. In experiments with single SWs in chemically active BW, a detonation-like mode of reaction front propagation (“bubbly quasidetonation”) was realized. This mode consisted of a SW followed by the front of bubble explosions and was characterized by a considerably higher propagation velocity as compared to the chemically inert BW. The latter could allow increasing the PDH operation frequency and thrust. Experiments with high-frequency SW packages showed that on the one hand, the individual SWs quickly merged, feeding each other and increasing the BW velocity, but on the other hand, the initial gas content for each successive SW decreased and, accordingly, the SW-to-BW momentum transfer worsened. Estimates showed that for a small-scale water guide 0.5 m long, the optimal pulsed detonation frequency was about 50–60 Hz.

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“…Research has found that the propulsion and specific impulse generated by the first detonation are significantly higher than the subsequent cyclic processes. To analyze the characteristics of the gas jet formed by a single detonation of the PDE, Liu [23] conducts an experimental and numerical simulation study of the single detonation of a PDE underwater, analyzing the expansion and shrinking process of the bubbles created by a gas jet via underwater detonation and the pressure characteristics of the flow field.…”

Section: Introductionmentioning

confidence: 99%

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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Bubble dynamics and pressure field characteristics of underwater detonation gas jet generated by a detonation tube

Cited by 20 publications

References 40 publications

Bubbles Management for Enhanced Catalytic Water Splitting Performance

Bubbles Management for Enhanced Catalytic Water Splitting Performance

Interaction of Shock Waves with Water Saturated by Nonreacting or Reacting Gas Bubbles

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

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