HIGH-SPEED STEREO-OBSERVATIONS OF VIOLENT VIBRATIONS ASSOCIATED WITH 3 TYPES OF CAVITATION

In order to improve the reliability of high-speed hydraulic machinery, detailed behavior of the violent vibrations appearing on a typically low-drag Eppler foil is systematically observed by means of high-speed stereophotography. We can clearly observe the following three types o f violent vibrations: (i) the vibrations resulting from a singly-attac hed cavity, usually arising at a higher incidence alpha(i), (ii) ones resulting from large travelling bubbles arising at a lower incidence, (iii) a mixture of these two types.