Gas Turbine Electric Start System (GT-ESS) Ship Integration

Abstract

The U.S. Navy has incorporated a realm of new technologies into ship warfare in the last few years. This availability has led to advances in ship machinery systems that have enabled the Navy to improve and sustain its mission capabilities. Since 2003, the Navy has worked with manufacturers to develop, test and evaluate a gas turbine electric starter system (GT-ESS) capable of meeting all starting requirements of the General Electric LM2500 marine gas turbine. This engine is used on U.S. Navy Surface Combatants for vessel propulsion. The GT-ESS has also been used to start a newly acquired naval engine from Rolls Royce, the MT30. The GT-ESS has endured extensive test and evaluation at the Land Based Engineering Site (LBES) of the Naval Surface Warfare Center, Carderock Division in Philadelphia, PA. Throughout this time the system has been redesigned as well to comply with more restrictive shipboard requirements. This effort had a direct impact on the packaging of the system. Additional effort has been directed to machinery integration. Full integration of the GT-ESS onto the LM2500 engine entails sharing a common lubrication and cooling loop. This is a challenge for the engine since its lubrication is critical for its service life. It poses a challenge for the GT-ESS since its design must guarantee that the lubrication system will remain free of contamination. The GT-ESS also poses integration challenges for a ship installation. The ideal location of the GT-ESS in the ship is adjacent to the propulsion engine within the machinery room space. Switchboards that provide power to the system are located several decks above the machinery space. Additionally, dedicated power supplies are required to handle the power requirements of the GT-ESS. Thus this power demand calls for an assessment of the power loads onboard ship. This new technology also has an impact on other ship systems. The GT-ESS driver is water cooled and designed to feed from the chill water system of the ship. Its electric motor lubrication has ties with another naval technology (digital fuel control). In turn these two are tied to the lube oil system and conditioning assembly (LOSCA) of the engine. Thus issues of oil pressure, temperature, backpressure, suction, and starvation are addressed and assessed. This paper explores the impact of ship machinery design for ship installation and its impact on other machinery systems as well as ship’s power. It targets proper hardware packaging as a means to achieve a well balanced design for ship application.