Large cavitation bubbles in the tube with a conical-frustum shaped closed end during a transient process

The transient process accompanied by extreme acceleration in the conical sections of hydraulic systems (e.g., draft tube, diffuser) can induce large cavitation bubbles both at closed ends and bulk liquid. collapses cause severe damage to solid walls. We conduct experiments tubes with different conical-frustum shaped `tube-arrest' method observe generated these two locations. For close end we propose onset criteria, consisting universal non-dimensional parameters $Ca_1$ $Ca_2$, separating water column. investigate their dynamics including collapse time speed. results indicate that larger angle, faster collapse. liquid, numerically study time, jet characteristics pressure pulse bubble a much stronger tubes, comparing near an infinite plate. Our provide guidance design safe operation machinery complex geometries, considering during process.