gas turbines
the DDG 117 and DDG 118 destroyers USS Paul Ignatius and USS Daniel Inouye. The gas turbines (four per shipset) will be delivered this year to the respective builders, General Dynamics/Bath Iron Works and Huntingdon Ingalls Industries. These LM2500 units will feature improvements made through GE’s common engine programme, including upgrades of the compressor rotor, turbine mid-frame, compressor rear frame and power turbine. The programme fosters cost control, enhanced manufacturing and durability, and reduced spares lead times. Common engine changes are contained within the gas turbine to avoid impact on ship interfaces and onboard maintenance activities. Overseas navies also continue to provide business for GE Marine. Three Hobart-class air warfare destroyers completing at the domestic ASC yard for the Royal Australian Navy (RAN) each incorporate twin LM2500 sets within a CODOG configuration. The ships are based on a design developed and applied by Navantia of Spain for the Spanish Navy’s F100 frigate programme. The RAN already operates 16 x LM2500 units in its Adelaide- and ANZAC-class frigates; further sets will be deployed in a pair of Canberra-class LHD vessels, each featuring
one gas turbine as part of a CODLAG system. A combined diesel-electric and gas turbine propulsion plant incorporating a single LM2500 will also drive the German Navy’s new F125-class frigates; the first of four such ships was christened in December at ThyssenKrupp Marine Systems in Hamburg, part of a German construction consortium. GE is supplying the LM2500 turbines from its Evendale, Ohio, facility to MTU Friedrichshafen in Germany for assembly into propulsion modules. Four LM2500 gas turbines together delivering 80MW will power the Indian Navy’s first domestic-built aircraft carrier, INS Vikrant, which will be handed over after extensive trials in late 2016/early 2017. The propulsion modules were assembled, inspected and tested in India by Hindustan Aeronautics using GE-supplied kits; the licensee’s modules also power three Indian Navy stealth frigates. LM2500 sets in service are benefiting from digital fuel control (DFC) system retrofits to improve gas turbine reliability and deliver lower maintenance and reduced long-term costs. The DFC kits from GE incorporate the most advanced controls now standard for new LM2500, LM2500+ and LM2500+G4 turbines in contrast to the hydro-mechanical control
systems of earlier generation sets. DFC technology secures more accurate fuel and air scheduling within the turbine installation through electrical feedback and closed-loop control; and fuel characteristics and variable stator vane (VSV) positions can be recalibrated via the control software inputs. Furthermore, gas turbine control sensor redundancy is available for compressor discharge pressure, compressor inlet temperature and pressure, gas generator speed, VSV position and fuel metering valve position. Improved operator signals, alarms and troubleshooting are provided by additional electrical sensors and actuator feedback. DFC kits also offer improved capabilities for data capture and condition monitoring as well as enhanced engine resistance to possible fuel contamination through oil actuation of the VSV fuel metering valve. GE Marine has teamed up with China’s Dalian Shipbuilding Industry Co and Lloyd’s Register to develop a gas turbine-powered LNG carrier design, reviving an earlier unsuccessful challenge in that market also mounted by Rolls-Royce. The growing popularity of gasfuelled propulsion solutions and an expanding LNG bunkering network should stimulate interest in gas turbine power for appropriate commercial tonnage. MP
Vericor targets fast naval and passenger projects Georgia, USA-based Vericor Power Systems’ is targeting fast patrol boat, attack craft, corvettes and hovercraft propulsion markets, while the compactness and light weight of its TF Series system have also earned installations in fast ferries and megayachts. The company’s pedigree extends over more than 30 years, although the company dates only from 1999. Its parentage started with AVCO Lycoming, which originated the TF Series marine gas turbines, and culminating with MTU Aero Engines.
Vericor TF Series turbines have operated successfully on a 50/50 mix of algae-based fuel and marine diesel oil
48 I Marine Propulsion I April/May 2014
Lycoming Turbine Engine was acquired in 1995 by AlliedSignal (now Honeywell) from Textron, along with its TF marine gas turbine. In 1999 AlliedSignal set up a joint venture with MTU Aero of Munich for marine and industrial business under the name Vericor Power Systems. Vericor became (and remains) a wholly-owned subsidiary of MTU Aero Engines in 2002. Vericor’s aero-derived TF Series gas turbines – TF40, ETF40B and TF50A models – cover continuous power ratings from just under 3,000kW to 3,803kW (with boost power ratings from 3,430kW to 4,176kW). Propulsion and electrical power generation applications in naval and commercial vessels are addressed. The cold end-drive turbine can be integrated into a package by cantilever mounting directly to the reduction gearing or mounting to a horizontal support frame and connecting to the gearing via a shaft and coupling. More powerful packages can be created by integrating two or three turbines in either side-by-side, over/under or Tripak configurations, depending on the space constraints of the hull.
Typical of Vericor’s fast naval installations are US Navy Landing CraftAir Cushion (LCAC) vessels, which feature four Vericor ETF40B engines for driving the lift and propulsion fans. Last year the US Navy ordered another eight ETF40B engines, taking the total to 16 for LCAC Service Life Extension Programme (SLEP) requirements in fiscal 2013. The engine delivers around 20 per cent more power than the model it replaces on LCACs, fostering improved performance in hot weather and a higher payload, as well as reducing life-cycle costs. The SLEP version of the LCAC extends service life from 20 to 30 years. TF Series gas turbines are designed to burn marine diesel oil, kerosene or jet fuel. Successful running on a 50/50 mix of algae-based fuel and conventional marine diesel has been demonstrated by an LCAC installation, however, with no operational problems or degradation of performance reported. A subsequent inspection found the engines to be cleaner than when operating on straight marine diesel.
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