Sympathetic underwater implosion in a confining environment

• We report sympathetic underwater implosion phenomenon in confining environments.
• Implosion inside an open ended confining tube generates strong water hammer waves.
• Water hammer implosion waves can initiate damage in adjacently placed structures.
• Sympathetic implosion can possibly be used for water hammer wave mitigation purposes.

An experimental study is conducted to investigate the phenomenon of sympathetic underwater implosion of cylindrical metallic shells in a confining environment. Two aluminum 6061-T6 implodable volumes with different collapse pressures are placed inside a confining tube with one end open to the environment and are hydrostatically loaded up to the weaker implodable volumes’ critical collapse pressure. Experiments show that implosion of the weaker implodable volume (critical pressure=Pc) inside the confining tube leads to the subsequent sympathetic implosion of the stronger implodable volume (critical pressure=1.2Pc). Implosion of the weaker implodable volume produces strong oscillating water hammer waves with 1.6Pc1.6Pc peak over-pressure, which initiates the implosion of the stronger implodable volume. Pressure histories recorded within the confining tube indicate that the sympathetic implosion of the stronger implodable volume generates low pressure high frequency implosion waves. The superposition of the low pressure waves with the high pressure water hammer waves mitigates to a great extent the later cyclic water hammer loading within the confining tube.

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