GE gas turbine chosen for Constellation-class frigate propulsion system

Written by Nick Blenkey
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An artist rendering of the new Constellation class formerly FFG (X) —guided-missile frigate . [U.S. Navy graphic]

GE Marine reports that it has been awarded a contract to provide shipbuilder Fincantieri Marinette Marine with a GE LM2500+G4 aeroderivative marine gas turbine to power the Navy’s first Constellation class (FFG 62) frigate. GE also will provide the gas turbine auxiliary skids (electric start, fuel forwarding and water wash systems) and the gas turbine control system.

The FFG 62 class (formerly FFG (X)) uses the Italian/French FREMM multipurpose frigate as the parent class design.The Constellation class frigates will use the same power dense GE LM2500+G4 gas turbine as the Italian Navy Carlos Bergamini class FREMM frigates in a COmbined Diesel eLectric And Gas turbine (CODLAG) propulsion system.

“The FFG 62 marks the initial U.S. Navy use of the LM2500+G4 engine,” says Kris Shepherd, Vice President, General Manager, GE Marine. “To date, 37 LM2500+G4 gas turbines have been chosen for surface combatants and two for commercial marine ships, as well as more than 1,100 of these engines operating worldwide in industrial settings.

The LM2500+G4 gas turbine for the new class of frigate is certified to a U.S. Navy rating of 30.3 MW (U.S. Navy standard day). GE will ensure the gas turbine and all associated auxiliary equipment is to specification compliance and fully integrated with the propulsion plant.

The LM2500+G4 will be supplied in GE’s state-of-the-art composite gas turbine module. One of the most important design features of this new module, says GE, is that it provides a safer environment and improved access for sailors. By using lightweight composites versus the steel enclosure predecessor, wall temperatures are 25ºF to 50ºF degrees cooler so there is less heat rejected into the engine room. GE also offers water mist fire suppression capability to the composite enclosure. The LM2500+G4 engine will be made at GE’s manufacturing facility in Evendale, Ohio.

The LM2500+G4 marine gas turbine was introduced in 2012 with the commissioning of the French Navy’s FREMM multipurpose frigate Aquitaine (also a 10-ship program). Since then, the LM2500+G4 has been selected for the Italian Navy’s FREMM frigates and PPA multipurpose offshore patrol ships; the first of seven PPA’s will be commissioned in 2021.

The LM2500+G4 fleet of naval and industrial engines has logged more than 4.5 million operating hours. GE’s cLM2500 family of engines have significant commonality, as all are two spool engines. The LM2500+ and LM2500+G4 differ from the LM2500 in that they have a zero-stage high pressure compressor blisk (bladed disk); and each have technical improvements to allow for increased air flow (22% and 33% greater air flow at ISO than the LM2500, respectively) and higher firing temperatures.

While the LM2500+G4 is extremely well proven, as we reported recently, the U.S. Congress has taken note that the FFG 62’s complex Combined Diesel Electric and Gas Hull, Mechanical and Electrical (HM&E) drive train has not previously been used on U.S. Navy ships. Accordingly, the just-passed National Defense Authorization Act (NDAA) for 2021 has a requirement that it be tested in a full-scale land based engineering and test site (LBETS) prior to delivery of the first ship in the new class.

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