Underwater implosion of glass spheres

Underwater implosion experiments were conducted with thin-wall glass spheres to determine the influence that structural failure has on the pressure pulse. Four experiments were conducted with glass spheres having an outside diameter of 7.62 cm , thickness of 0.762 mm , and an estimated buckling pressure of 7.57 MPa . The experiments were performed in a pressure vessel at a hydrostatic pressure of 6.996 MPa . The average peak pressure of the implosion pressure pulse was 26.1 MPa , measured at a radial distance of 10.16 cm from the sphere center. A computational fluid structure interaction model was developed to assess how the failure rate of the glass structure influences the pressure time history. The model employed a specified glass failure sequence that is uniform in time and space. It was found that for the conditions of the test, a glass failure rate of 275 m ∕ s provided a reasonable representation of the test data. The test data and the model results show that the failure time history of the structure has a significant influence on an implosion pressure pulse. Computational prediction of an implosion pressure pulse needs to include the failure time history of the structure; otherwise it will overpredict the pressure time history.