Cavitation damage as a result of polyfractional erosion process

Abstract

The paper reports on the progress in development of the fractional model of cavitation erosion kinetics. The model was proposed by the author in the end of nineties as a tool aimed at overcoming the incompatibility in cavitation erosion resistance assessments based on tests conducted at different facilities. The methodology proposed assumes testing materials under different conditions and describing their resistance to each load fraction under consideration by parameters of an analytic function modelling the monofractional cumulative erosion curves. A differential superposition law is used to derive the erosion curve under a polyfractional impingement. The fractional model has been used to retrieve cavitation load at test facilities involved in the International Cavitation Erosion Test project and to predict erosion at a rotating disk rig basing on the results of the cavitation tunnel tests. The technique of determining the erosive load basing on the pressure pulses amplitude distribution is currently considered the main weakness of the approach. Statistical analysis of pit distribution in a soft material in the initial period of erosion and the use of research results of LEGI lab (Grenoble, France) is proposed as a solution. Some further research aimed at refining the methodology is suggested as well.