Water Piston Engine for Marine Vehicle Propulsion

This paper describes an environment friendly propulsion system with negligible noise. The Propulsion system is based on a novel engine called a water piston engine. All moving parts in the classical internal combustion engine are eliminated; the piston, connecting rod, and crankshaft. Also, cams and follower valves are replaced by solenoid valves which inject compressed air into the cylinders. A water column in the cylinder is used to replace the metallic piston. The water column itself inside the cylinder acts as a piston. This Water Piston Engine is powered by pressurized air only. So, a pressure vessel is used to store compressed air. The Pressure derived from the compressed air tanks is directly used in providing thrust by pushing the water out of the cylinder through a 90-degree elbow as a water jet. When the water is ejected from the cylinder and the air pressure inside the cylinder decreases to near atmospheric, the water that surrounds the engine fills the cylinder. Four cylinders are used; each two cylinders are fired simultaneously in order to maintain thrust. This system uses an Arduino microcontroller unit to deal with how much time the pressurized air is needed to discharge the cylinder and to switch the airflow between the engine cylinders. Several field tests have been made in a lake. The experimental data were compared to the theoretical based data in addition to simulate this model using Ansys fluent. The advantages of this novel engine over internal combustion engines are clarified. Videos of the experiments are recorded.