Circulatory drive

The closed-circuit drive is a method for propulsion of submarines that is independent of the outside air . It essentially consists of a diesel engine that is operated underwater with compressed or liquid oxygen.

history

The circular drive was developed in Germany during the Second World War and, with and after the Walter drive, was the most advanced submarine drive of its time. From 1944 onwards, almost all submarine designs by the Office for Warship Construction were equipped with a closed-circuit drive. Due to the end of the war, however, the planning and test bench runs remained.

After the war, the outside air-independent Walter technology was tested by England, the United States and the Soviet Union ( Project 615 ). However, accidents in the handling of the concentrated hydrogen peroxide soon led to the discontinuation of further development.

Today the closed-circuit drive is still used in some civil submersible vehicles, such as the TOURS class. In conventionally powered military submersibles, diesel-electric propulsion has largely been retained. A few newer boats use closed-circuit drives based on turbines ( MESMA system ) to increase range and speed. With the further development of passive sonar technology , quieter drives and thus fuel cells appear increasingly advantageous.

Working principle

The diesel engine works with outside air when sailing above water or snorkeling. For a deeply submerged ride, it is switched to circulation. Instead of the outside air, a mixture of carbon dioxide from the exhaust gas and oxygen from the boat's supply is used, which contains a similar proportion of oxygen as the outside air. In this way, the proportion of oxygen in the combustion air mixture remains the same. A pressure regulator ensures that exactly the right amount of exhaust gas is pushed outboard to keep a constant pressure in the circuit. The oxygen is stored either in pressurized gas bottles or in cryogenic / LOX in cylindrical tanks, the latter being more space-saving but technically more complex.

literature

Ulrich Gabler, Fritz Abels: Unterseebootbau , Bernard & Graefe, Koblenz 1997, ISBN 3-7637-5958-1 .