Combined gas and gas
{{Short description|Two-turbine, one-shaft marine propulsion}}
Combined gas turbine and gas turbine (COGAG) is a type of propulsion system for ships using two gas turbines connected to a single propeller shaft. A gearbox and clutches allow either of the turbines to drive the shaft or both of them combined. Marine usage of COGAG systems are similar to those found ashore.{{sfn|Soares|2015|pp=10, 27}}
Description
{{Combined-marine-propulsion}}
A COGAG system consists of two gas turbines, each connected to a reduction gearbox. These are each attached to a coupling with both connected to larger gearbox and then to the ship's propeller.{{sfn|Plaff|2021|p=95}}
Advantages and disadvantages
Advantages of the system include a large degree of automation along with quick startup time, they are easier to silence and protect from shock.{{sfn|Graves|Carleton|1963|p=12}} Compared to combined diesel and gas (CODAG) or combined diesel or gas (CODOG), COGAG systems have a smaller footprint but a much lower fuel efficiency at cruise speed and for CODAG systems it is also somewhat lower for high speed dashes.{{sfn|Soares|2015|p=31}} Issues with COGAG systems include their complexity and gearbox issues and high fuel use.{{sfn|Plaff|2021|p=92}}
List of COGAG ships
- {{Sclass|Kolkata|destroyer|0}} guided-missile destroyer (Indian Navy)
- {{INS|Vikrant|2013|6}} (aircraft carrier) (Indian Navy)
- Type 22 frigate (Batch 3) (Royal Navy)
- {{Sclass|Invincible|aircraft carrier|1}} (Royal Navy)
- {{Sclass|Cavour|aircraft carrier|1}} (Italian Navy)
- {{Sclass|Asagiri|destroyer|1}} (Japan Maritime Self-Defense Force), and subsequent destroyer classes
- {{Sclass|Hyūga|helicopter destroyer|1}} (Japan Maritime Self-Defense Force), helicopter carrier
- {{Sclass|Izumo|helicopter destroyer|1}} (Japan Maritime Self-Defense Force), helicopter carrier
- Type 055 destroyer (People's Liberation Army Navy)
- {{Sclass|Neustrashimy|frigate|1}} (Russian Navy)
- {{Sclass|Sejong the Great|destroyer|1}} (Republic of Korea Navy)
- {{Sclass|Skjold|corvette|1}} (Royal Norwegian Navy)
- {{Sclass|Arleigh Burke|destroyer|1}} (United States Navy)
- {{Sclass|Ticonderoga|cruiser|1}} (United States Navy)
Citations
{{reflist}}
References
- {{cite journal |title=Gas Turbines for Unconventional Craft |last1=Graves |first1=G. L. |last2=Carleton |first2=R. S. |journal=Bureau of Ships Journal |date=September 1963 |volume=12 |number=9 |pages=7–12}}
- {{cite book |last=Plaff |first=Manfred |date=2021 |title=Ship Operation Technology: Reference Book and Guidebook |publisher=Springer Fachmedien |location=Wiesbaden, Germany |isbn=978-3-658-32729-3}}
- {{cite book |last=Soares |first=Claire |date=2015 |orig-year=2008 |title=Gas Turbines: A Handbook of Air, Land and Sea Applications |edition=Second |publisher=Elsevier |location=Kidlington, Oxford |isbn=978-0-12-410461-7}}