This paper proposes a new type of nozzle which generates a high-speed two-phase water jet as a propulsion device for a ship. The high-pressure gas accelerates the two-phase jet by temporal and local pressure gradients ; therefore, the principle of accelerating water flow is different from that of jet pumps. A two-dimensional nozzle was set in a towing tank, and the thrust was measured for various parameters such as pressure of the injection gas, towing speed, air injection angle, and front and/or near opening angle. The thrust increases monotonically as the gas pressure increases for all flow velocities, but it converges to a maximum value. The propulsion effeciency increases as the flow velocity increases, but it is higher when the gas pressure is lower. It was proven that the proposed device is applicable to ship propulsion by operation of a model ship using this device.
