Direct inducer cavitation instability identification using high speed visualization

Abstract

Direct identification of inducer cavitation instability was conducted via high speed video footage without pressure information. A two-bladed inducer undergoing alternate blade cavitation has been tested. The fluctuation of grayscale values for each pixel were shown to be closely correlated with the actual pressure fluctuation. Using each frame of the high speed video footage, not only the classic visual inspection, but also quantitative method including traveling wave energy analysis and mode analysis was performed. By only using the pixel grayscale fluctuation data, quantitative methods, which have been only applied to the pressure signals to identify the cavitation instabilities, were also successively applied and the type of cavitation instability was well determined.