Cavitation Erosion-Corrosion Modeling.

摘要

Due to the increased occurrence of cavitation erosion in hydrodynamic systems operating in an ocean environment, there is a need to study the role of corrosion on the process of cavitation erosion. Previously, for noncorrosive systems, correlation of experimental data with the theory of erosion resulted in a time-scale modeling law of erosion. The changes in this scaling law due to corrosion were then investigated. A high-frequency, 20 Khz, piezoelectric vibratory apparatus was employed to generate erosion time history data for HY-130, HY-80, SAE 1020 steels, and Al 5086 H117 at several different erosion intensities in sea and distilled water. Results indicated that the relative erosion rate curves for materials susceptible to corrosion were different, and that the changes due to corrosivity increased with increasing erosion intensities. By coupling changes in corrosivity with maximum erosion rate increases, and times to the maximum rates, it is possible to make prototype performance predictions for either seawater or distilled water conditions. Qualitative relationships were found between the relative erosion rates and galvanic potentials of tested materials. A mechanism was proposed to account for the corrosive influence on erosion based on hydrogen-generated micropit destruction of a material surface that accelerates cavitation erosion. (Author)