Study on the Performance Improvement of Ship Propulsion Equipment Directly Driven by High-Pressure Gas

(The Effect of Intermittent Gas Ejection and a Flow Visualization Study inside the Nozzle)

Abstract

The flow inside the two-dimensional semi-open-type nozzle for ship propulsion equipment, directly driven by high-pressure gas was investigated experimentally. The flow was unsteady and the gas and water phases clearly separated. We found that these waves appear on the interface for continuous gas ejection. It was clarified that waves play an important role in the pressure distribution. Intermittent gas ejection was also tried. The thrust itself decreases compared with continuous gas ejection, but propulsion efficiency, considering the gas ejection duration is increased. The flow patterns for intermittent gas ejection were also clarified.