The Influence of Surface Irregularities on Cavitation: Field Study and Limited Cavitation near Wire Screen Roughness.

摘要

Two sizes of wire screen roughness height (0.015 and 0.046 inches) have been experimentally investigated to determine their wall shear stress and cavitation characteristics. The wall shear stress was computed from the boundary layer velocity profile utilizing the law of the wall. Desinent cavitation numbers were obtained visually with varying free stream velocity. The maximum range in velocity was from 30 to 46 feet per second. The maximum range in velocity was from 30 to 46 feet per second. The linear relationship between cavitation inception and wall shear stress, characteristic of distributed roughness, was verified. An investigation was also made of real surface roughness to determine the relative size of real irregularities, what types exist and where they occur, what types are isolated or distributed, and what types may contribute most to the occurrence of cavitation. The results of this study will be applied in a program to determine the tolerance on real surface roughness for a specified cavitation performance. (Author)