Experimental and numerical investigations of liquid mercury droplet impacts

Abstract

A broad investigation into the hydrodynamics of liquid mercury has been motivated of late by its use in MW-scale spallation neutron sources. One area of particular concern relates to the erosion suffered by vessel walls from the cumulative effects of liquid mercury droplet impacts arising from the collapse of cavitation bubbles. The low speed (< 5m/s) range of such events forms the focus of this paper and to this end a series of experiments is conducted on spherical droplets of diameter 2:5mm impacting upon a dry quartz surface. A reasonable simulation of such impacts is made possible by using the VOF (volume of fluid) solver interFoam (a part of the open source package OpenFOAM) in combination with an empirical expression for the dynamic contact angle of the air-mercury-quartz system. This latter represents a ‘best fit’ to data obtained from high resolution imaging of the droplet profile for a range of contact line velocities. Experiment and simulation are subsequently compared throughout the stages of initial deposition, spread, recession with break-up and, finally, bounce.

Keywords

• mercury
• mercury droplet impacts
• mercury droplet breakup
• surface tension
• volume of fluid method
• openfoam’s interfoam