The water jet propeller is powered by a water pump, sucking water from the bottom hole of the ship, discharging the water from the rear of the ship through the side pipe, and relying on the reaction force of the water to propel the ship. The basic principle of water jet propulsion: By spraying water with a certain speed on a ship or other aircraft in the opposite direction of its movement, the hull will receive the reaction force of the water flow based on the action force and reaction force, and this force is the thrust. The magnitude of thrust = the rate of change of momentum per unit time when the fluid flows through the propeller flow channel. The thrust on a waterjet propulsion device can be defined as the resultant force of pressure and shear stress on all the inner surfaces of the propulsion device in contact with water in the opposite direction of the nozzle area vector. These surfaces include the inlet duct, impeller, impeller bushing and nozzle.
