Image post-processed approaches for cavitating flow in orifice plate

A comprehensive investigation on cavitating flow and cavitation-induced erosion was performed experimentally in an orifice plate system. Three image post-processed approaches were applied to analyze the test data, in order to obtain the cavitation characteristics. The cavitating flow pattern was studied by high speed images. In one cavitation developing period, there could be three distinct cavitation clouds, whereas the second one is not fully developed. The first image post-processing approach was applied to obtain the mean value and standard deviation distribution, which indicate the erosion area may cover almost all the cavitation developing route and the most vulnerable erosion area locates near the cavitation collapse site. It is coincides with the erosion tests analyzed through the pit-count algorithm approach. The cavitation circulation frequency was invested via PSD analysis approach. It shows that the frequency linearly decreasing with decreasing cavitation number. Additionally, the cavitation intensity effect on cavitation erosion was quantitatively studied based. It is found that the damages are strongly enhanced when increasing the flow velocity. Moreover, the growth rate of eroded pits number is actually stepwise instead of linear (similar to our previous work in a venturi tube), which supports the idea that the cloud cavitation collapse is the primary reason for erosion. The present approaches applied here shows good potential ability of investigating cavitating flows and can be utilized for other apparatus.