Publication

Water drops and cavitation bubbles in microgravity

Mohamed Farhat, Danail Obreschkow, Philippe Kobel
2005
Conference Papers

Abstract

We realized an experimental setup to study the dynamics of cavitation bubbles inside spherical water drops produced in microgravity (8th Student Parabolic Flight Campaign, European Space Agency ESA). Water volumes of up to 8 ml (25 mm diameter) were expelled through a specially designed injector tube. The latter contained a porous hydrophilic foam and was particularly coated to ensure a stable and attached water drop. Single cavitation bubbles were then generated by an electrical discharge inside the drop. The growth and collapse of the bubble were recorded using a high-speed visualization system (24’000 frames/s). Thereby, we could study for the first time the cavitation phenomenon in microgravity and observe the interactions between cavity and spherical free surface. In particular, the microjet/counterjet formation was visualized and significant counterjet broadening was found when passing from planar to spherical free surfaces.

Official source

https://infoscience.epfl.ch/entities/publication/58e33c1a-7422-4fbc-90de-265df92ac932

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Mohamed Farhat, Danail Obreschkow, Philippe Kobel
2005
Conference Papers

Abstract

Official source

https://infoscience.epfl.ch/entities/publication/58e33c1a-7422-4fbc-90de-265df92ac932

About this result

Related concepts (25)

Cavitation

Cavitation is a phenomenon in which the static pressure of a liquid reduces to below the liquid's vapour pressure, leading to the formation of small vapor-filled cavities in the liquid. When subjected to higher pressure, these cavities, called "bubbles" or "voids", collapse and can generate shock waves that may damage machinery. These shock waves are strong when they are very close to the imploded bubble, but rapidly weaken as they propagate away from the implosion. Cavitation is a significant cause of wear in some engineering contexts.

Gas-discharge lamp

Gas-discharge lamps are a family of artificial light sources that generate light by sending an electric discharge through an ionized gas, a plasma. Typically, such lamps use a noble gas (argon, neon, krypton, and xenon) or a mixture of these gases. Some include additional substances, such as mercury, sodium, and metal halides, which are vaporized during start-up to become part of the gas mixture. Single-ended self-starting lamps are insulated with a mica disc and contained in a borosilicate glass gas discharge tube (arc tube) and a metal cap.

Corona discharge

A corona discharge is an electrical discharge caused by the ionization of a fluid such as air surrounding a conductor carrying a high voltage. It represents a local region where the air (or other fluid) has undergone electrical breakdown and become conductive, allowing charge to continuously leak off the conductor into the air. A corona discharge occurs at locations where the strength of the electric field (potential gradient) around a conductor exceeds the dielectric strength of the air.