2-Stroke Marine Diesel Engine
2-stroke marine diesel engines are the primary source of propulsion for large cargo ships, tankers, and bulk carriers. These massive low-speed engines are among the most efficient internal combustion engines in the world, designed to operate continuously under heavy loads for long ocean voyages.
Unlike automotive or medium-speed engines, a 2-stroke ship engine completes a full power cycle in a single crankshaft revolution. This design allows the engine to produce extremely high torque at low rotational speeds, enabling the crankshaft to drive the propeller directly, without the need for a gearbox.
Combustion and Gas Exchange Process
After combustion, hot exhaust gas exits the cylinder through an exhaust valve located in the cylinder head. As the piston continues downward, scavenge ports open near the bottom of the cylinder liner, allowing fresh, oxygen-rich air to flow in.
This incoming air pushes the exhaust gas out of the cylinder while simultaneously refilling it for the next combustion cycle. This process is known as uniflow scavenging, a key feature of modern 2-stroke marine engines.
Turbocharging and Air Supply
Fresh air is supplied by a turbocharger, which converts exhaust gas energy into compressed intake air. Before entering the cylinder, the air passes through an air cooler to reduce its temperature and a mist catcher to remove water droplets. Cooler, cleaner air improves combustion efficiency and protects internal engine components.
Fuel Injection and Power Generation
Fuel oil, typically Heavy Fuel Oil (HFO) or marine diesel is injected directly into the combustion chamber at very high pressure. The fuel ignites due to the high temperature of the compressed air, producing a powerful downward force on the piston. This force turns the crankshaft and drives the ship’s propeller.
Camshaft vs Electronic Control System (ECS)
Traditional marine engines use a camshaft-driven system to control fuel injection and exhaust valve timing. Modern engines increasingly rely on Electronic Control Systems (ECS), which use computer control and hydraulics to precisely manage engine timing. ECS technology improves fuel efficiency, operational flexibility, and emissions performance.
Because of their massive size and internal complexity, 2-stroke marine diesel engines are difficult to understand through photos or diagrams alone. High-quality 3D animation makes it possible to clearly visualize airflow, combustion, valve motion, fuel injection, and mechanical interaction inside the engine, processes that cannot be seen in real operation.