Title: Study on Flow Phenomenon inside a Nozzle of a Ship Propulsion Equipment Directly Driven by High Pressure Air (Experimental Consideration of Flow inside a Nozzle According to Water-Flow Velocity)
Abstract: An experimental study by means of pressure measurements and flow visualization was performed to investigate unsteady flows inside a two-dimensional semi-open-type nozzle for a ship propulsion equipment directly driven by high-pressure gas. We found that ejected gas phase and water-flow phase are separated clearly of themselves, and the interface of these phase behave like interfacial waves. It is clarified by flow visualization with a high speed motion camera and a circulating water channel that these interfacial waves change their shapes according to water-flow velocity. The interfacial wavelength becomes longer in response to increasing water-flow velocity, and the mechanism that obtains thrust on the nozzle-wall changes. The thrust and flow patterns for the intermittent gas ejection according to water-flow velocity are also clarified.