A toroidal bubble is a vortex ring with a gas core in a liquid. Current interest in toroidal bubbles is partially due to the discovery that small toroidal bubbles can occur in the cavitation collapse of a spherical bubble near the surface of a solid. This can occur near a propeller blade, causing both damage and acoustic emission. Another motivation is that dolphins generate a rich variety of large vortex bubbles. The objectives of this thesis are the construction of an apparatus that generates large toroidal bubbles in a tank of water, and the establishment of the parameter space in which toroidal bubbles occur. The apparatus employs a variable electrical input, interchangeable solenoid valve, interchangeable needle valve, and pressurized nitrogen gas. The tank is an acrylic cylinder with diameter one foot and height four feet. It is observed that whether or not a toroidal bubble forms is highly stochastic. This is studied by varying several parameters of the apparatus. Preliminary results of possible acoustic emission are presented. Future work with the apparatus is discussed, including digital photography of toroidal bubble formation and the effect of ensonification on the motion.
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