Confined Underwater Implosions Using 3D Digital Image Correlation

This study experimentally investigates fluid structure interactions occurring during confined implosions using high-speed digital image correlation (DIC). Aluminum tubular specimens are placed inside a confining cylindrical structure with one end open to a pressurized environment. These specimens are exposed to hydrostatic pressure, which is slowly increased until they collapse onto themselves. The implosion event is viewed through an acrylic window on the confining structure. Full field deformation and velocities are captured with DIC and are synchronized with the pressure history. Experiments show that implosion inside a confining structure leads to extremely high oscillating water hammer effects. Both peak structural velocities and hammer impulses increase linearly with increasing collapse pressure.