On the Cavitation Occurring at the Bottom of a Suddenly Accelerated Circular Cylinder. Effects of Air Content in Water on Incipient Cavitation.

This study is intended to investigate the cavitation at the end surface of a cylinder when this is impulsively put into a longitudinal motion along its axis. The principle is that a longitudinal stress wave accompanying the longitudinal particle displacement is generated at one end of the cylindrical rod by an impact given at the other end ; the stress wave then propagates into the adjacent water as pressure fluctuations causing cavitation when the negative pressure reaches a certain value with a certain time duration. The results of the investigation can be summarized as follows (1) Cavitation is more susceptible with the air content in water. The pressures at the onset of cavitation increase with the air content. (2) Though the minimum pressures at the test surface decreases with increasing impact speed of the rod, the cavitation occurs at a pressure higher than the minimum and this incipient pressure is almost independent of the impact speed. (3) The incipient cavitation pressure can be negative when the air content in water is reduced from the saturated value.