Experimental investigation on the property of high-speed ventilated supercavitation

The submerged vehicles can achieved super-high speed by virtue of the technique of supercavitating drag reduction. The comprehensive model experiments were conducted to research the gas entrainment property of ventilated supereavity in the high-speed water tunnel at NPU. Several dimensionless variables about ventilated cavity such as the gas entrainment coefficient, cavitation number and drag coefficient were investigated experimentally. The different shape and size of ventilated supercavity that controlled by volumetric gas quantity were obtained. The amount of ventilation gas required to maintain the artificial ventilation cavity at different natural cavitation number was presented. The relationships between cavitation number and gas entrainment coefficient were researched by measure quantitatively the average pressure of the cavity. In addition, the drag coefficients that at least depend on the cavitation number was also investigated experimentally. It was shown experimentally that increase of gas entrainment coefficient causes to increase of the cavity relative length. The lower of ventilated coefficient corresponds to the smaller natural cavitation number when the same cavity length holds. The experimental results indicated that the maximal ratio of drag reduction coefficient can exceed 85% compared with the case of fully wetted. It can be conclude that the cavitator must be matched reasonably with afterbody of the given model for the sake of the optimization efficiency of drag reduction.