GE LM2500+G4

History

The GE LM2500+G4 is the fourth generation of the LM2500 marine gas turbine family. GE Aerospace describes it as the most powerful and efficient member of the family, with substantially greater output than the original LM2500 while retaining the same basic footprint.

The LM2500+G4 was introduced in 2012. It has been used for naval propulsion and is also available in a generator-set configuration for electrical generation applications.

The engine currently powers FREMM frigates operated by Italy, France, Egypt, and Morocco. It has also been selected for additional naval programs in the United States and South Korea.

Development

The LM2500+G4 was developed from the LM2500+ with increased flow capacity and materials derived from more recent aircraft-engine technology. Compared with the base LM2500, the LM2500+G4 incorporates a zero-stage high-pressure compressor blisk and technical changes that increase airflow by 33 percent. Higher permissible firing temperatures contribute to the increased power output while the engine retains the footprint of the base LM2500.

GE Aerospace states that the LM2500+G4 provides 41 percent more power than the base LM2500. Technical information for the engine is available from the GE Aerospace LM2500+G4 page.

Naval selections

The LM2500+G4 was selected for the United States Navy Constellation-class FFG-62 frigate program. It was later selected for the DDG(X) Land Based Test Site while the United States Navy develops the design of its future destroyer class.

In 2026, the Republic of Korea Navy selected the LM2500+G4 for the KDDX next-generation destroyer program. GE Aerospace is to supply 12 engines for six ships, with two engines installed in each destroyer. The engines are planned to operate as part of the KDDX full electric propulsion configuration. The selection was reported by Naval News and Asia-Pacific Defence Reporter.

For the KDDX installation, each engine will be enclosed in a lightweight composite enclosure developed by GE Aerospace. Compared with the previous steel enclosure, the composite design reduces weight by more than 2,500 kg while retaining the same footprint as the base LM2500 installation. GE Aerospace also states that the enclosure reduces noise by 60 percent and lowers wall temperatures by approximately 14 to 28 degrees Celsius, corresponding to the reported reduction of 25 to 50 degrees Fahrenheit.

Hanwha Aerospace is to manufacture various engine components in South Korea and will assemble, test, and provide service support for the KDDX engines in the country. NRTEC in Busan is to manufacture the lightweight composite engine enclosure locally.

Design

The LM2500 family uses a two-spool gas turbine architecture. The LM2500+G4 retains this family configuration while incorporating changes intended to increase airflow, operating temperature, and power output.

Compressor and hot section

A major difference from the base LM2500 is the addition of a zero-stage high-pressure compressor blisk. Together with other aerodynamic and thermal improvements, this contributes to a 33 percent increase in airflow. Advanced materials derived from aircraft-engine technology permit higher operating temperatures.

Maintenance

The engine uses a modular design intended to simplify repair and refurbishment. Supported maintenance features include a split compressor casing, in-place replacement of blades and vanes, in-place hot-section maintenance, and externally accessible fuel nozzles.

Marine and electrical applications

The LM2500+G4 can be used for mechanical marine propulsion or as a generator set. Its combination of high output and a footprint comparable with the base LM2500 permits it to be integrated into warships requiring increased propulsion or electrical-generation capacity without a corresponding increase in the basic engine footprint.

Operational history

The LM2500+G4 currently powers FREMM frigates in Italian, French, Egyptian, and Moroccan service. These operational installations demonstrate the engine's use in large modern surface combatants.

The engine has subsequently been selected for newer naval programs including the United States Navy Constellation-class frigate program, the DDG(X) Land Based Test Site, and the Republic of Korea Navy KDDX destroyer program. The KDDX installation is planned around two LM2500+G4 engines per ship in a full electric propulsion configuration.

Operators

• Italy: LM2500+G4 engines power Italian FREMM frigates.
• France: LM2500+G4 engines power French FREMM frigates.
• Egypt: LM2500+G4 engines power Egyptian FREMM frigates.
• Morocco: LM2500+G4 engines power Moroccan FREMM frigates.

Program status

The United States Navy selected the LM2500+G4 for the Constellation-class FFG-62 program and for the DDG(X) Land Based Test Site. The available sources do not establish operational service of these specific installations.

For South Korea's KDDX program, GE Aerospace is to provide 12 engines for six planned destroyers. Each ship is planned to receive two LM2500+G4 engines. Local participation includes component manufacturing, engine assembly, testing, service support, and production of the composite enclosure in South Korea.

Specifications (LM2500+G4)

General characteristics

• Type: Two-spool marine gas turbine engine
• Rated output: 35,320 kW (47,370 shp)
• Specific fuel consumption: 214 g/kW-hr (0.352 lb/shp-hr)
• Exhaust gas flow: 93 kg/s (205 lb/s)
• Exhaust gas temperature: 549 degrees Celsius (1,020 degrees Fahrenheit)
• Power turbine speed: 3,600 rpm

GE Aerospace states that these performance figures represent average performance at 60 Hz, 15 degrees Celsius, sea level, 60 percent relative humidity, and without inlet or exhaust losses.