Evidence for hydrogen generation in laser- or spark-induced cavitation bubbles

Sato, Takehiko; Tinguely, Marc; Oizumi, Masanobu; Farhat, Mohamed

doi:10.1063/1.4793193

Cited by 40 publications

(37 citation statements)

References 28 publications

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“…Varying ∆p likely also varies this gas content, which varies the energy partition into the rebound for spherical collapses [11], and could be the reason for lower ∆p yielding relatively bigger rebounds in Figure 2. Indeed, the gas inside the bubble, in our experiment, likely comprises i) laser-generated gas, as has been reported in the past [12] -we assume this gas pressure to be proportional to the energy deposited by the laser to generate the bubble; ii) non-condensible gas, for which we assume the partial pressure to be proportional to the bubble volume; iii) diffused gas, for which we assume the partial pressure to be proportional to the total exposed bubble surface being covered during its lifetime; and iv) vapour, the partial pressure of which is assumed to be the vapour pressure of the liquid, p v , during most of the bubble's lifetime, but which may act as a non-condensible gas in the final collapse stages due to its condensation rate not being able to keep up with the bubble's rapid reduction in volume [13]. Much more thorough modeling is needed to obtain proper predictions of the gas effects on the rebound dynamics.…”

Section: Discussionsupporting

confidence: 72%

On the Rebounds of Spherical and Deformed Cavitation Bubbles

Supponen¹,

Obreschkow²,

Farhat³

2018

Proceedings of the 10th International Symposium on Cavitation (CAV2018)

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As a single cavitation bubble collapses, its energy is distributed into several powerful phenomena that contribute to its erosive potential. These events are the emission of shock waves that can reach GPa-level pressures, microjets reaching speeds of hundreds of ms −1 , and the extreme heating up to temperatures in the order of 10,000 K, which may yield light emission called luminescence. Much of what is left of the bubble's energy from its redistribution to these violent collapse effects goes to the formation of a rebound bubble, which will undergo its own collapse and can produce further damage. Here, we experimentally investigate the effect of a bubble's deformation on its rebound using single laser-induced bubbles deformed by gravity. While the driving pressure also affects the rebound dynamics, the bubble deformation dominates over its effect on the rebound beyond a certain level of pressure field anisotropy. Thanks to micro-gravity conditions, we are able to decouple the effects of the driving pressure and the gravity on the rebound.

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Section: Discussionsupporting

confidence: 72%

On the Rebounds of Spherical and Deformed Cavitation Bubbles

Supponen¹,

Obreschkow²,

Farhat³

2018

Proceedings of the 10th International Symposium on Cavitation (CAV2018)

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“…7), the plasma has fully recombined ( Fig. 9c), leaving a bubble filled with water vapor and minor amounts of other gases (Sato et al, 2013).…”

Section: Phase I: Bubble Generationmentioning

confidence: 99%

The quest for the most spherical bubble: experimental setup and data overview

et al. 2013

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We describe a recently realized experiment producing the most spherical cavitation bubbles today. The bubbles grow inside a liquid from a point-plasma generated by a nanosecond laser pulse. Unlike in previous studies, the laser is focussed by a parabolic mirror, resulting in a plasma of unprecedented symmetry. The ensuing bubbles are sufficiently spherical that the hydrostatic pressure gradient caused by gravity becomes the dominant source of asymmetry in the collapse and rebound of the cavitation bubbles. To avoid this natural source of asymmetry, the whole experiment is therefore performed in microgravity conditions (ESA, 53rd and 56th parabolic flight campaign). Cavitation bubbles were observed in microgravity (∼ 0g), where their collapse and rebound remain spherical, and in normal gravity (1g) to hyper-gravity (1.8g), where a gravitydriven jet appears. Here, we describe the experimental setup and technical results, and overview the science data. A selection of high-quality shadowgraphy movies and time-resolved pressure data is published online.

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“…After either laser-or spark-induced cavitation bubbles collapse, there are undissolved gases. The main component of the gases may be hydrogen produced by the plasma [18].…”

Section: Introductionmentioning

confidence: 99%

Improved Instruments and Methods for the Photographic Study of Spark-Induced Cavitation Bubbles

Zhang

Zhai

2018

Water

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An underwater spark is able to induce a cavitation bubble, and this principle has been utilized to make cavitation bubble generators for several decades. In this paper, an improved instrument for generating spark-induced cavitation bubbles is described in detail. The voltage time history inside the instrument is measured to show the working process and principle. Cavitation bubbles are generated by the instrument and recorded by a high-speed camera. The radius time history of the bubble is obtained using an image processing algorithm. The ratio of its minimum radius to its maximum radius reaches ~0.2, which indicates that there is little undissolved gas in the bubble. With the radius time history, the velocity fields around the bubbles were calculated by the 1D continuity flow equation, and the pressure fields were calculated by the 1D Euler equation. One cavitation bubble is chosen and discussed in detail. The velocity and pressure on the bubble interface achieve their maximums (~25 m/s and ~1.2 MPa, respectively) at the same time, when the radius is at its minimum (~1 mm). Some statistical results are also presented to show the effect of the instrument.

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Evidence for hydrogen generation in laser- or spark-induced cavitation bubbles

Cited by 40 publications

References 28 publications

On the Rebounds of Spherical and Deformed Cavitation Bubbles

On the Rebounds of Spherical and Deformed Cavitation Bubbles

The quest for the most spherical bubble: experimental setup and data overview

Improved Instruments and Methods for the Photographic Study of Spark-Induced Cavitation Bubbles

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