On Testing Materials for Cavitation Damage Resistance

Abstract

Recent experiments with a magnetostriction apparatus show that cavitation-damage rate is time dependent. This is confirmed by an analysis of the experimental data obtained in various earlier investigations. There are four zones of damage rate with respect to testing time; namely, (a) incubation, (b) accumulation, (c) attenuation, and (d) steady state. In the fourth, or steady-state zone, the damage rate varies as the square of the amplitude of oscillation within the range tested for water at 80 F. The damage rate increases with frequency and then decreases with increasing frequency. The depth of liquid in the beaker, the beaker diameter and the depth of immersion of the specimen do not seem to affect the damage rate substantially. The average depth of erosion is independent of the diameter of the specimen. Based on these experimental results, certain recommendations are made for testing materials for cavitation damage resistance.

Discussion: “Effect of Exposure Time on Cavitation Damage” (Plesset, M. S., and Devine, R. E., 1966, ASME J. Basic Eng., 88, pp. 691–699)

“…The result that the decrease in cavitation damage rate is due to the interaction of the surface roughness on the hydrodynamics of bubble collapse confirms our own earlier conclusion, reference [2] of the original paper. The second conclusion that "the depth of deformation of the structure does not change even after appreciable surface erosion has taken place" does not contradict any of our results.…”

“…In light of these facts, none of our results reported in references [1][2][3][4][5] of this paper are proven erroneous by the conclusions of these authors. The unsubstantiated remarks of these authors about our investigations characterizing them as "misinterpretations" and "misunderstandings" are, we believe, due to their own lack of understanding of our results.…”

A review on synergy of cavitation and sediment erosion in hydraulic machinery

“…frontiersin.org as well as sediment erosion and the complex interaction between cavitation and sediment particles, lead to great challenges in understanding the physical mechanism of synergy between cavitation and sediment erosion. Specifically, the typical cavitation erosion curves (volume loss in time and volume loss rate of erosion) show four stages: incubation stage, acceleration, deceleration, and equilibrium (Thiruvengadam and Preseir, 1964;ASTM G32-16, 2016;ASTM G134-17, 2017), while sand erosion has no incubation period and damage is proportional to time. Sediment erosion alone which is approximately the 3rd power of velocity causes 4 times more weight loss than cavitation erosion alone which is approximately the 6th power or higher of velocity, and combined action causes 16 times weight loss (Mei and Wu, 1996).…”