title: The implosion of cylindrical shell structures in a high-pressure water environment.
abstract: The implosion of cylindrical shell structures in a high-pressure water environment is studied experimentally. The shell structures are made from thin-walled aluminium and brass tubes with circular cross sections and internal clearance-fit aluminium end caps. The structures are filled with air at atmospheric pressure. The implosions are created in a high-pressure tank with a nominal internal diameter of 1.77 m by raising the ambient water pressure slowly to a value,Pc, just above the elastic stability limit of each shell structure. The implosion events are photographed with a high-speed digital movie camera, and the pressure waves are measured simultaneously with an array of underwater blast sensors. For the models with larger values of length-to-diameter ratio,L/D0, the tubes flatten during implosion with a two-lobe (mode 2) cross-sectional shape. In these cases, it is found that the pressure wave records scale primarily withPcand the time scale [Formula: see text] (whereRiis the internal radius of the tube andρis the density of water), whereas the details of the structural design produce only secondary effects. In cases with smaller values ofL/D0, the models implode with higher-mode cross-sectional shapes. Pressure signals are compared for various mode-number implosions of models with the same available energy,PcV, whereVis the internal air-filled volume of the model. It is found that the pressure records scale well temporally with the time scale [Formula: see text], but that the shape and amplitudes of the pressure records are strongly affected by the mode number.
authors.affiliation: Department of Mechanical Engineering , University of Maryland , College Park, MD 20742, USA.
authors.forename: C M
authors.initials: CM
authors.lastname: Ikeda
authors.affiliation: Department of Mechanical Engineering , University of Maryland , College Park, MD 20742, USA.
authors.forename: J
authors.initials: J
authors.lastname: Wilkerling
authors.affiliation: Department of Mechanical Engineering , University of Maryland , College Park, MD 20742, USA.
authors.forename: J H
authors.initials: JH
authors.lastname: Duncan
keywords: fluid–structure interaction; implosion; sound waves