Publication de 4 numéros par an
ISSN Imprimer: 2169-2785
ISSN En ligne: 2167-857X
Indexed in
EXPERIMENTAL MEASUREMENT OF THE ELECTRIC FORCES ACTING ON A GROWING GAS BUBBLE IN QUASI-STATIC CONDITIONS
RÉSUMÉ
This work was aimed at measuring the resulting electric forces acting on a gas bubble growing quasistatically, with gas supplied to it through a circular orifice, and to compare them with their theoretical counterparts. An experimental apparatus has been set up, consisting essentially of an orifice drilled in a flat stainless steel plate submerged in the test fluid (FC−72). A dedicated gas injection system allowed creating slowly growing or even static bubbles of any desired volume, up to the detachment volume. An electric field could be imposed by means of a washer-shaped electrode laid parallel to the surface and centered on the orifice. The apparatus could be operated with the orifice both in upward and in downward direction to investigate the favorable or adverse role of the buoyancy force. Data were acquired via a highresolution video camera, equipped with a microscopic lens, and were digitized and processed via dedicated software, implemented in Matlab. The resulting forces acting on the bubbles were derived from bubble shape and size. The data in the absence of electric field were compared with their theoretical counterpart to validate the method and the image processing technique and showed an excellent agreement. In a second phase, data with electric field were acquired. The resulting electric force was evaluated from the force balance, as the opposite of the sum of all the other forces acting on the bubble. The values of measured electric forces showed excellent agreement with the theoretical evaluations.
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