A ventilated supercavitation is a technology which can generate a supercavitation in relatively low speed by gas injection and obtain a stable shape of cavity.
In this paper, the experimental equipments for ventilated supercavitation in cavitation tunnel is constructed and the basic data of ventilated supercavitation regard to the entrainment coefficient and Froude number is fulfilled. The experiments are conducted for disk cavitator with injecting air and the pressure inside cavity and the shape of cavity are measured.
As the entrainment coefficient increases and the Froude number is constant, the ventilated cavitation number decreases to a minimum value which is no more decreased even increasing the entrainment coefficient. The minimum value of ventilated cavitation number, caused by the blockage effect, decreases according to increasing which is the diameter ratio of test section to cavitator. The cavity length is rapidly enlarged near the minimum cavitation number.
In low Froude numbers, the cavity tail is up due to buoyancy and the air inside the cavity is evacuated with twin-vortex mode. However in high Froude numbers, there is no more twin vortex mode and the cavity shape becomes to axisymmetric so that the buoyancy effect is almost negligible.
In order to measure the cavity length and width, the two methods, which are to be based on the cavity shapes itself(Def, B) and the maximum width of cavity(Def. A), are applied. As the entrainment coefficient increases after the ventilated cavitation number address the minimum cavitation number, the cavity length gradually large but the ventilated cavitation number is constant to minimum cavitation number. These phenomenon can be explained by the measurement using ‘Def. B’. On the other hand, when the ‘Def. A’ is used, the results of the cavity length and width agree well with semi-empirical formular of natural cavity. So ‘Def. A’ can be a valid method with respect to cavitator design.