Subsurface microtunneling in ductile material caused by multiple droplet impingement at subsonic speeds

0555114 - ÚGN 2023 RIV CH eng J - Journal Article
Hloch, Sergej - Souček, Kamil - Svobodová, J. - Hromasová, M. - Müller, M.
Subsurface microtunneling in ductile material caused by multiple droplet impingement at subsonic speeds.
Wear. Roč. 490-491, February 2022 (2022), č. článku 204176. ISSN 0043-1648. E-ISSN 1873-2577
R&D Projects: GA MŠMT(CZ) LO1406
Institutional support: RVO:68145535
Keywords : hydrodemolition * periodic water impingement * lateral flow * subsurface erosion * transient cavities * blind cavities * pulsating water jet * fractal erosion patterns * hydraulic penetration
OECD category: Mechanical engineering
Impact factor: 5, year: 2022
Method of publishing: Open access

This article deals with the analysis of the subsurface deformation effects of materials due to the periodic action of liquid droplets, each with a constant volume of approximately 36 mm(3) distributed with a spatial frequency of 20,000 i/mm. Sample grooves were analyzed within standoff distances where the prevailing mechanism is acceleration culmination depletion using the stair trajectory to avoid a possible Doppler effect. Using X-ray mu-CT, a network of cavities corresponding to a fractal shape was identified below the surface. It is apparent that the ability to erode does not end with the formation of a groove but continues into the core of the material in the form of microjetting, tunneling, or piercing. From that perspective, two types of these cavities have been identified, blind and transient, with diameters of a few micrometers. The topological changes in the subsurface region of the sample were analyzed using X-ray tt-CT progressive sectioning. The anticipated subsurface deformation was further explored and analyzed using SEM analysis. The integrity of the material around the cavities was assessed according to microhardness to explain the microjetting, tunneling, and piercing propagation. The results suggest that the effect of the lateral jetting after droplet collapsing causes extensive hydrodynamic tunneling in the material that is much higher during the intense periodic action of water droplets, even at subsonic speeds.
Permanent Link: http://hdl.handle.net/11104/0330896