The fire and other component tests verified the use of a composite material to markedly reduce weight and improve performance. In addition, the package design has progressed to incorporate updated package sensors and components.
Participants of the MMP include GE, General Dynamics Bath Iron Works and the United States Navy; the program commenced in 2014.
“Ships are constantly challenged by weight to meet present and future capability needs and to lower life cycle costs,” said GE’s Brien Bolsinger, Vice President, General Manager. “That’s why the MMP is designed with customer needs in mind: to update the gas turbine module with proven new technologies that reduce the enclosure weight by approximately 50%, while also reducing life cycle costs, noise emission and improving safety.”
The new monolithic composite structure of GE’s LM2500 marine module does not use bolted joints between the walls and ceiling. This feature greatly improves assembly and noise attenuation through the elimination of noise channels. The use of composites also allows the module doors and access panels to be made larger, yet lighter for ease of handling. The use of composites eliminates rusting of doors, hinges and access panels, reducing maintenance while improving safety.
Fire testing was conducted at Southwest Research Institute (SwRI) to validate that the composite design meets U.S. Navy fire resistance requirements. SwRI is an accredited testing laboratory and a third-party quality assurance and inspection agency.
The SwRI testing also revealed the following:
- Module composite wall passed direct flame and indirect heat impingement tests, which tests emitted smoke and gas toxicity.
- The composite wall and ceiling panel passed fire resistance and structural integrity tests. These tests measured the materials’ capacity to withstand a rapid rise fire and the structural ability to carry load (including firefighting personnel) during a fire event. The panel was subjected to a rapid rise in temperature and held at 2000 degrees F.
- Tests and analysis of steel and composite wall sections subjected to 500 degrees F – along with the full package calibrated heat transfer analysis — showed marked improvements with the GE composite wall design. These tests suggest that external skin temperatures would be reduced.
- Acoustic panel comparison tests showed improvements in transmitted sound pressure (dBA) levels.
The MMP focuses on the GE-designed enclosure that surrounds the entire LM2500 gas turbine (inlet, engine and exhaust) that serves several important functions. The enclosure limits heat rejection to the machinery room and provides thermal protection to the crew from the >1000 degrees F temperatures radiating from the gas turbine and exhaust. The enclosure forms an acoustic and fire boundary around the gas turbine for the safety of the ship. Based on testing, the new LM2500 composite enclosure will better attenuate noise while maintaining the same fire resistance characteristics as the steel enclosure.
Fully certified to U.S. Navy shock requirements
The assembly of a prototype enclosure is now underway and will be tested in a full-scale gas turbine test cell to confirm noise attenuation and thermal performances predicted earlier by component tests and analysis. The composite enclosure will then be subjected to barge shock testing to U.S. Navy requirements. These tests are scheduled to be completed by mid-2018.
The gas turbine module developed under the MMP will be available in 2018 with the first application intended on the U.S. Navy’s DDG-51 Flight III ships. The lightweight composite enclosure and updated components will be available for international navies in 2018, as well. Separately, GE is presently manufacturing a retrofit composite door assembly for a naval customer.
Worldwide, more than 1,400 GE gas turbines log over 14 million hours serving 35 navies on 500 naval ships for 100 military ship programs ranging from patrol boats, destroyers and cruisers to corvettes, frigates, amphibious ships and aircraft carriers.
Companies: GE Aviation