Temporal evolution of thermocavitation bubbles using high speed video camera

Padilla-Martínez, Juan Pablo; Aguilar, Guillermo; Ramírez-San-Juan, J. C.; Ramos-Garcı́a, R.

doi:10.1117/12.894467

Cited by 10 publications

(9 citation statements)

References 15 publications

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“…Due to the short light penetration depth (∼74 µm), changing the position of the focal point only changes the volume of the superheated volume and, therefore, the size of the bubble and amplitude of the emitted shockwave. 7,29 In contrast, bubbles created with short pulsed lasers in transparent solutions are always produced at the focal point where the intensity is the highest. The left-most image in Figure 2(a) corresponds to the shadow produced just before vapor bubble formation.…”

Section: Experimental Descriptionmentioning

confidence: 99%

Optic cavitation with CW lasers: A review

et al. 2014

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The most common method to generate optic cavitation involves the focusing of short-pulsed lasers in a transparent liquid media. In this work, we review a novel method of optic cavitation that uses low power CW lasers incident in highly absorbing liquids. This novel method of cavitation is called thermocavitation. Light absorbed heats up the liquid beyond its boiling temperature (spinodal limit) in a time span of microseconds to milliseconds (depending on the optical intensity). Once the liquid is heated up to its spinodal limit (∼300 °C for pure water), the superheated water becomes unstable to random density fluctuations and an explosive phase transition to vapor takes place producing a fast-expanding vapor bubble. Eventually, the bubble collapses emitting a strong shock-wave. The bubble is always attached to the surface taking a semi-spherical shape, in contrast to that produced by pulsed lasers in transparent liquids, where the bubble is produced at the focal point. Using high speed video (105 frames/s), we study the bubble’s dynamic behavior. Finally, we show that heat diffusion determines the water superheated volume and, therefore, the amplitude of the shock wave. A full experimental characterization of thermocavitation is described.

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Section: Experimental Descriptionmentioning

confidence: 99%

Optic cavitation with CW lasers: A review

et al. 2014

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“…The width and height of the liquid column can be influenced by the laser parameters and the droplet's volume. The laser power and beam focus position determine the bubble size and consequently, the APW amplitude driving the column's formation (Korneev et al, 2011;Padilla-Martinez et al, 2011) and force exerted on the interface, while the droplet volume determines the width and height of the liquid column. In order to determine the effect of the APW, the laser focus position was varied from z = 0 to z = 400 µm in intervals of 100 µm, inside a droplet of 20 µL volume.…”

Section: Resultsmentioning

confidence: 99%

“…The present paper reports observations and a theoretical model of the evolution of thermocavitation bubbles (Ramirez-San-Juan et al, 2010Korneev et al, 2011;Padilla-Martinez et al, 2011) formed inside a highly absorbing liquid droplet using a midpower (275 mW) continuous wavelength (CW) laser. The acoustic pressure wave (APW) produced immediately after bubble collapse creates stable liquid columns whose length exceeds its circumference (L > 2πR), beyond the traditional onset of R-P Atomization and Sprays instability.…”

Section: Introductionmentioning

confidence: 99%

Breaking the Rayleigh-Plateau Instability Limit Using Thermocavitation Within a Droplet

et al. 2013

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We report on the generation of liquid columns that extend far beyond the traditional Rayleigh-Plateau instability onset. The columns are driven by the acoustic pressure wave emitted after bubble collapse. A high-speed video imaging device, which records images at a rate of up to 10 5 fps, was employed to follow their dynamics. These bubbles, commonly termed thermocavitation bubbles, are generated by focusing a midpower (275 mW) continuous wavelength laser into a highly absorbing liquid droplet. A simple model of the propagation of the pressure wavefront emitted after the bubble collapse shows that focusing the pressure wave at the liquid-air interface drives the evolution of the liquid columns. Control over the aspect ratio of the liquid column is realized by adjusting the cavitation bubble's size, beam focus position, and droplet volume.

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“…The vapor bubbles produced by this method are commonly termed as thermocavitation bubbles. Further details concerning thermocavitation and its dynamics can be found in [32,34,35,[41][42][43][44]. The laser-induced bubble is always in contact with the substrate taking a hemispherical shape.…”

Section: A Vapor Bubble Formation and Liquid Jet Evolutionmentioning

confidence: 99%

Controllable direction of liquid jets generated by thermocavitation within a droplet

et al. 2017

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A high-velocity fluid stream ejected from an orifice or nozzle is a common mechanism to produce liquid jets in inkjet printers or to produce sprays among other applications. In the present research, we show the generation of liquid jets of controllable direction produced within a sessile water droplet by thermocavitation. The jets are driven by an acoustic shock wave emitted by the collapse of a hemispherical vapor bubble at the liquid-solid/substrate interface. The generated shock wave is reflected at the liquid-air interface due to acoustic impedance mismatch generating multiple reflections inside the droplet. During each reflection, a force is exerted on the interface driving the jets. Depending on the position of the generation of the bubble within the droplet, the mechanical energy of the shock wave is focused on different regions at the liquid-air interface, ejecting cylindrical liquid jets at different angles. The ejected jet angle dependence is explained by a simple ray tracing model of the propagation of the acoustic shock wave inside the droplet.

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Temporal evolution of thermocavitation bubbles using high speed video camera

Cited by 10 publications

References 15 publications

Optic cavitation with CW lasers: A review

Optic cavitation with CW lasers: A review

Breaking the Rayleigh-Plateau Instability Limit Using Thermocavitation Within a Droplet

Controllable direction of liquid jets generated by thermocavitation within a droplet

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