Erosion behavior of aluminum by an inclined cavitating jet

Abstract

The erosion behavior of pure aluminum by an inclined cavitating jet in the acceleration period was experimentally investigated for potential applications in peening and cleaning. The mass loss and surface topography of the eroded specimens were investigated to unravel the erosion mechanism under inclined impingement with various feeding pressure. The cavitation cloud motion was numerically investigated in various erosion stages with two-phase CFD calculation. Results show that at the first optimum standoff distance of mass loss l1 close to the nozzle bottom, erosion occurs in two ring-like areas, whereas the erosion at the downstream second optimum standoff distance l2 appears as a single ring at inclined angles αi∈ [0∘, 15∘] and as separated crescent-shaped areas at αi = 30∘ and 45∘. The increasing αi induces a higher cumulative erosion ratio in the acceleration period at Pin = 15 MPa and 13 MPa, whereas the aggressive ability of inclined impingement is attenuated at Pin = 11 MPa due to the low cavitation intensity. An obvious transition from plastic deformation to erosion damage is found on the boundary of the main erosion area. Under the inclined impingement, the upper side of the main erosion area shows much more severe erosion damage than the lower side due to the blocking effect, where the upward spread of the cavitation clouds is blocked and their collapse primarily occurs in the erosion valley. The erosion develops with the a ring-shaped pattern at αi∈ [0∘, 5∘]. At higher inclined impingement angles αi∈ [15∘, 45∘], the erosion primarily develops along the surface normal direction in the part of the main erosion area closer to the nozzle exit.