Experimental Investigation on Cavity Pressure Inside Sheet Cavitation

Abstract

The gas content is one of the important factors in cavitation, which may increase the pressure inside the cavity through the diffusive mass transfer of the dissolved gas into the cavity. In the present study, we try to directly measure the cavity pressure inside the sheet cavity at the throat of a converging-diverging nozzle. Then the influences of the flow velocity and the gas content (amount of dissolved oxygen) on the gas partial pressure are investigated. It is found that, even in low gas content level, the cavity pressure is slightly but apparently higher than the saturated vapor pressure, indicating the presence of gas partial pressure. It is observed that the gas partial pressure in significantly developed cavitation is almost constant regardless of the flow velocity but slightly increases against the increase of the saturation level of dissolved gas. It is also found that the gas partial pressure inside cavity depends on the degree of cavitation development; the gas partial pressure decreases with the development of cavitation.