THE AMERICAN SOCIETY OF MECHANICAL ENGINEERS ,98-GT=41; „ 345E 47th St, New York, N.Y:10017 • • •

The Sodety shall not be•responsible for statements cir opinions advanced in papers or &mission. at meetings of the Sodety or oils Dions or ' Secaone, or rend in its publications. Discussion is printed only if the paper is published in an ASME journal. Authorization to Photocopy . • for internal or personal use is granted to libraries and other users registered with the Copyright Clearance Center (CCC) provided 53/article or $4/page is paid to CCC: 222 Rosewood Dr., Danvers, MA 01923. Requests .tor special permission• • or- bulitreproduction„ • should be addressed to the ASME.Technical publishing Department. Copyright 0 1998 by ASME All Rights Reserved Downloaded from http://asmedigitalcollection.asme.org/GT/proceedings-pdf/GT1998/78637/V002T03A001/2409728/v002t03a001-98-gt-041.pdf by guest on 01 October 2021

Extending Use of Marine Gas Turbines through Application of the LM2.500+

David L. Luck GE Marine and Industrial Engines 11111111111 ,1111111111 General Electric Company Evendale, Ohio

Abstract Applications The propulsion configurations of current powered military and Military propulsion systems commercial vessels have been established based include a variety of configurations, including the upon available power ratings of existing most commonly used combined prime mover engines, relative to the performance combinations, which are referred to as CODOG requirements of ship builders and operators. ' ( Turbine) and Development of the LM2500+ engine has COGAG (COmbined Gas turbine and Gas extended power capability with minimal Turbine). CODOG has been used where the changes to the physical parameters of the maximum power for high speed is provided by current LM2500 marine packages. This paper the gas turbines, while the low speed more explores the extended possibilities of gas turbine economical operation has been provided by based propulsion in both military and small diesels engines. For larger where commercial vessels through application of the maximum total power requires multiple increased gas turbine power in packages of (usually four) gas turbines, the lower speed essentially current size and weight such as the operation is provided by using a lesser number' LM2500+. of the installed engines.

Background Smaller vessels (less than 2000 tons displacement) of the or patrol vessel Gas turbines have become firmly classes have been able to achieve satisfactory established for applications performance with a single gas turbine CODOG, over the last 20 years, including extensive use in combined with multiple small diesels for low military vessels, and growing application in speed operation. CODOG propulsion specific segments of the commercial marine configurations for larger vessels (above 2000 market. The development of aeroclerivative gas tons displacement) have generally required at turbines, i.e. those derived from flying engines, least two gas turbines in order to achieve the has made efficient engines with a proven track required speed. The availability of higher power record of operation available for use in a variety marine gas turbines has the potential to extend of ship classes. use of the simpler and less expensive single gas

Presented at the international Gas Turbine & Aeroengine Congress & Exhibition Stockholm, Sweden — June 2-June 5, 1998 turbine CODOG to and larger size used simultaneously. For a ODGAG vessels. configuration, maximum power is generated from the combination of gas turbines. Figure 1 indicates the approximate distribution of the various configurations in Figure 1 shows no CODAG . ( Turbine) configurations, although that alternative is now The power requirement fix various ship being implemented for the German F124 and is classes indicated in Figure 1 depends not only being considered for a number of other projects. Downloaded from http://asmedigitalcollection.asme.org/GT/proceedings-pdf/GT1998/78637/V002T03A001/2409728/v002t03a001-98-gt-041.pdf by guest on 01 October 2021 on the ship displacement but on the maximum For the CODAG configuration the total power speed required. The total power indicated on available for maximum speed becomes the sum the horizontal axis represents the maximum of the gas turbine and diesel power. For the total power available to achieve the maximum CODAG configuration, use of a larger gas speed. For a CODOG configuration, maximum turbine can extend the Single Gas Turbine power is generated from the gas turbine(s), region well into the region of Two Gas Turbine because the diesels and gas turbine(s) cannot be ship classes.

Diplom Total raw•r

Two arrow

Gas Tortilla COO AO —7

Two .

00000 - On Turbin• CO 000

Single • •• 0•• Turblas • . • I C0000 • 000

•

•

20.0 30.0 404 50.0 00.0 70.0 00.0 TeS11.0wWW.1, Figure 1 Distribution of Gas Turbine Power Plants in Warships

independently drive waterjets, allowing Commercial Ship Applications simultaneous operation of both prime mover types. Multiple gas turbines are also used in the Gas turbines have only recently been COGAG configuration. Higher rated gas put to serious use in commercial ships, as the turbines offer extended capability in both compact, low weight characteristics of the commercial configurations. engines have satisfied an urgent need. The development of the fast ferry market (generally Changes in the Marine Market vessels carrying over 50 passengers at over 25 knot speed) created a growing sector of volume The range of gas turbine sizes applied sensitive ships carrying low density cargo, such in the commercial marine market has been 3 as passengers and cars, which need compact and MW to about 23 MW. Low power applications light weight propulsion systems (1,2). have generally been in very weight sensitive Similarly, cruise ships place a premium on ships such as hydrofoils. The largest efficient use of internal ship volume, and commercial ship applications have total power represent a potential application area (3). requirements of approximately 68 MW or more Commercial ship propulsion configurations also resulting in multiple gas turbine COGAG. include CODAG (Combined Diesel And Gas Commercial vessel configurations have included Turbine), where the diesels and gas turbines catamarans and monohull vessels.

2 total power is therefore the sum of that available Many catamaran vessels have been from all prime movers. The German F124 built which use two sets of propulsion systems vessels will employ CODAG with a single gas with total power less than 30 MW. The fast turbine and two diesels. Use of this same ferry trend has moved towards larger vessels concept with a more powerful gas turbine can with more capacity, operating at speeds over 40 allow propulsion of larger ships with a single knots. This trend in larger catamarans requires gas turbine, up to the size that had previously total power over 50 MW, divided into two required two gas turbines in a CODOG Downloaded from http://asmedigitalcollection.asme.org/GT/proceedings-pdf/GT1998/78637/V002T03A001/2409728/v002t03a001-98-gt-041.pdf by guest on 01 October 2021 systems for the two catamaran hulls. A arrangement. considerable advantage in volume, weight, and cost can be realized if that power can be What does the LM2500+ bring? provided by a single gas turbine in each hull. The LM2500 gas turbine has In the military marine sector, powering established a long history of operation in requirements are changing for a different military marine applications and is now being reason Instead of continued growth to larger used also in commercial marine vessels (1,2). ships with larger power requirements, a down The engine has evolved though a systematic sizing trend seems to be indicated. Instead of program of component improvements which the larger , destroyers, and cruisers have increase the available power (4) and the which have dominated naval shipbuilding in maintenance and reliability (5). The available recent years, interest in vessels of the offshore power rating of the LM2500 for military marine patrol vessel and corvette size is increasing. applications is 22 MW for U. S. Navy and up to Ships of these classes normally have 23.5 MW for some other international navies displacements around 2500 tans or less, as depending upon the definition of their rating compared to the larger combatant vessels of conditions. In commercial applications with 4000 tons and larger common in earlier continuous power requirements at maximum programs. output, the LM2500 has been applied at 21 to 22 MW depending upon the condition of operation Smaller ships do not necessarily mean for the vessel. less capable ships. The operational capability requirements for these smaller ships are in some The LM2500+ development extends the ways more difficult to achieve than with larger available power while maintaining substantial ships, since the combat systems payload is commonality with the current LM2500. The extensive. In addition, the speed requirement LM2500+ will be ISO rated at 29 MW after the for these ships must usually match the capability accumulation of some operating experience with of an existing fleet. larger ships have used initial installations. The marine rating for multiple gas turbines to achieve the speed continuous operation is slightly over 26 MW for required, which is normally 30 knots or greater. ambient temperature operation at about 20° C. Small ships of 1200 ton displacement can The engine therefore provides approximately 5 achieve this speed with a single gas turbine in a MW additional power for most typical marine CODOG configuration. Ships with 2000 ton or applications. The marinized technology of the more displacement have required two gas 1242500 is carried forward in the LM2500+ turbines or have settled for diesel propulsion and with a large degree of commonality in lower speed. To maximize the payload of these components. Long experience in ship operation ships while providing the operational speed helps to ensure that LM2500+ is designed for needed, a single gas turbine CODOG systems is that environment. desirable, because of the weight, space and cost savings. Design of the LM2500+

Revival of the previously employed The increase in power available with CODAG (Combined Diesel And Gas Turbine) is the LM2500+ is realized through increased air cccurring in military shipbuilding. This flow. An increase in operating efficiency is also configuration allows the operation of diesel and achieved through a small increase in firing gas turbine power sources simultaneously. The temperature. Specific improvements in each

3 major assembly of the LM2500+ have been the standard combustors resulting in greater previously published (6). For completeness the temperature margin than in the LM2500, even major upgrades are summarized as follows: though the firing temperature is increased. Materials and coating upgrades in the RFT Compressor blades and nozzles plus improvements in cooling will result in longer operating intervals One additional stage of compressor blades has between refurbishments for these items, even at been added forward of the LM2500's first stage the higher ratings of the LM2500+. blades. The number of compression stages is Downloaded from http://asmedigitalcollection.asme.org/GT/proceedings-pdf/GT1998/78637/V002T03A001/2409728/v002t03a001-98-gt-041.pdf by guest on 01 October 2021 increased to 17 (from 16) and the air flow is Power turbine increased by about 20% relative to the LM2500. Compressor airfoils for stages two and three Redesigned power turbine blades and increased have increased efficiency. Overall the disk sizing has been incorporated in the compressor pressure ratio increases from 18.8 LM2500+ to support the higher torque for the LM2500 to 23.1 for the LM2500+. associated with increased power. These improvements have also increased the low cycle Hot Section (Combustor and high pressure fatigue limits of the power turbine. This is turbine) especially important for fast ferry applications, which generally have highly cyclic operating Improved materials in the hot section result in a profiles. more durable configuration with longer repair intervals. Thermal bather coating is added to

LM2500+ New compressor stage 0, HP turbine material Redesigned PT blades VIGV, now pant mods and cooling upgrades and increased disk sizing T t.it‘ttio .,11[11141111111 Allatillibilli 1 1_ III II a !vain', .... ri■---alsidieZ A k aNIm ■ 11111...t. ZIMINIThrrrri,FATi,A. 0 II"•rnorsh.Ailllii ,„., rifires. • ' 1' all 6 ""itlirt- 1.,114130 LM2500

Figure 2- Comparison of LM2500+ with LM2500

Installation Parameters for Marine are the improvements in power per unit volume Applications and weight which the LM2500+ provides. Because gas turbines are of most interest for Table 1 compares the specific ships which are volume limited, i.e. those which installation and performance parameters of the carry light density cargo, the improved power LM2500+ to the current LM2500. Increased density translates directly into additional efficiency and power output are reflected in the revenue producing space in commercial vessels. table. Of additional interest for ship application In military vessels the reduction in volume

4 occupied by the propulsion prime mover results to the LM2500 because the package is in greater combat systems payload. essentially the same. This further reduces first cost per unit power for a ship installation A likely reduction in cost per unit because of the increased power available. power makes LM2500+ more attractive on a first cost basis. Installation costs are very close

Installation and Performance Parameters Downloaded from http://asmedigitalcollection.asme.org/GT/proceedings-pdf/GT1998/78637/V002T03A001/2409728/v002t03a001-98-gt-041.pdf by guest on 01 October 2021

Parameter Unit LM2500LM2500+ ISO Power Rating MW 25 29 SFC (at ISO rating) gm/kw-hr 227 218 Thermal Efficiency 96 37.0 38.4 Weight * mton 14 15 Volume * cubic meters 63.6 66.8 Power/unit volume KW/cu meter 393 434 Power/unit weight KW/KG 1.78 1.93

* Typical commercial marine installation package

Table 1

The Military Marine Market to achieve 30 knots is of the order of 27 MW (7). Although current diesels can provide that The current trend in military warship level of power with 4 x 20 cylinder systems, a construction is toward smaller vessels such as considerable weight and volume penalty is paid. or offshore patrol vessels in the 1000 to 2000 ton class. This trend has been noted for Competing requirements are placed at least the last three years and is driven by two upon military ship developments from two factors: first is the general reduction in defense categories, operational requirements and life budgets and the high cost of larger ships; cycle cost limitations. Operational requirements second is the increased attention to the include such capabilities as a) carrying a possibility of regional conflicts versus the past helicopter, b) supporting vertical launch for concentration on global wars. Smaller vessels anti-air and anti-ship warfare, c) having low satisfy requirements for littoral operations, and detectibility which means low noise, 111, and provide capability for extended capability as radar signatures, d) being able to achieve 30 well. knot top speed, e) maintaining long endurance on station or extended range. Life cycle costs For the low end of the surface requirements include a) reduced manning, b) combatant displacement spectrum (1000 to 1200 low maintenance, and c) reduced fuel tons), the propulsion requirements can be expenditure. satisfied by multiple diesel CODA]) plants if lower speed (25 knots or less) is adequate for the The combination of operational mission. If greater speed is required, a single requirements listed above drive the propulsion gas turbine CODOG plant can provide speeds in configuration to deliver high power with low excess of 30 knots. Examples are the Korean weight and volume for the system. Previous Dons Hae and Po Hang classes, the Danish designs have made use of two gas turbine Niels Ale] class and the Israeli Eilat class. CODOG configurations for larger vessels to When additional capability is required, i.e. more achieve the required power. CODAG combines combat system capability or the requirement to the smaller cruise diesels with the gas turbine to carry larger helicopters is added, the increase the boost power, but this results in displacement of the ship approaches 1800 to considerable complication in controlling the 2000 tons. At 2000 tons the power requirement combination of diesels and gas turbines, and

5 requires a multiple speed input gear to use the required operating conditions which may diesels at a wide range of speeds effectively. include ambient temperatures at 20 to 25° C.

Availability of the LM2500+, which The LM2500+ at a commercial rating can provide the required power for 30 knots in a of approximately 26 mw may satisfy the 2000 tons vessel, has several benefits. First the requirements of the larger catamaran with one initial cost, volume and weight of the propulsion engine in each hull. This simple cycle, low system is reduced relative to 4 diesels CODAD weight propulsion system may extend the size of or the 2 gas turbine CODOG. Second, the economically viable catamaran vessels to over Downloaded from http://asmedigitalcollection.asme.org/GT/proceedings-pdf/GT1998/78637/V002T03A001/2409728/v002t03a001-98-gt-041.pdf by guest on 01 October 2021 operational benefits of gas turbine operation are 100 meter length. Lower vibration, reduced realized, including reduced manning for emissions, and reduced maintenance are likely maintenance and operation, much lower from this simple propulsion configuration, and acoustic signature for ASW operations, and will complement the design advantages of lower greater low speed range because of the more propulsion weight and volume. efficient cruise diesels combined with the larger fuel load. The other segment of the high speed commercial market which continues to expand The Commercial Marine Market is the fast monohull vessel. Early application of a single LM2500 in combination with MTU The commercial marine market for fast diesels in the Rodriquez built Aquastrada class ferries has developed in at least three distinct has proven successful in over 5 years of segments. At the low vessel size and power end operation. Larger monohulls are now being (less than 10 MW total power), the market is built, both with multiple diesel CODA]) by dominated by the , except where BAZAN and with multiple LM2500 gas turbines weight and volume are so critical that gas CODAG by Fuicantieri. turbines are required. Examples of such ships include the Kvaerner Fjellstrand Foilcat and the Application of the higher power FBM Tricat. At the high end of the market available from the LM2500+ extends the size of where total power required is over 60 MW, monohull vessels which can be powered by a multiple gas turbines are required because the single gas turbine CODAG. A vessels of 120 weight and volume of diesel engines is meter length with 200 car capacity achieving prohibitive. The middle of the market is over 40 knots operating speed is possible with characterized by catamarans of the 74 to 90 this configuration. metes size which have power requirements about 24 to 28 MW. These have been satisfied by four Summary high speed diesel engines, although gas turbines have penetrated this market to a smaller extent. Propulsion configurations for both An example of gas turbine propulsion in this military and commercial vessels employing gas size vessels is the Danyard Seajet 250. This has turbines have been developed around available been the fastest growing segment of the market size power units. In the military configurations. with a large number of vessels sold. Larger CODOG plants with one or two gas turbines and vessels are being offered as more operating COGAG two or four gas turbine plants have experience is accumulated. become standard. Commercial vessels have fallen into two categories also. Catamarans The trend of the medium size have two or four gas turbines COGAG, catamaran market is toward larger vessels with monohuils have one or two gas turbine CODAG. increasing power requirements. Designs are presently being considered with a power Market evolution in both military and requirement exceeding 50 MW to achieve speed commercial vessels has created a need for a in the 40 knot range. Power requirements of 50 higher power gas turbine unit. Military vessels MW are beyond the capacity of a four diesel of the corvette size need a larger gas turbine for power plant, but may be achieved with gas a single CODOG or a more powerful CODAG. turbines capable of continuous ratings at the Demand for vessels of this type is increasing due to changing military requirements and budgets.

6 Fast commercial vessels are changing as the market develops. Larger catamarans require increased power to permit applications over 100 meters with two gas turbines. Monohull vessels are increasing in size beyond 120 meters. A higher power engine allows single gas turbine CODAG to provide the required power for these vessels. Downloaded from http://asmedigitalcollection.asme.org/GT/proceedings-pdf/GT1998/78637/V002T03A001/2409728/v002t03a001-98-gt-041.pdf by guest on 01 October 2021

The availability of the LM2500+ responds to the broader requirements of both the military and commercial vessel designs. Higher power with minimal increase in physical weight and volume for the propulsion system extends the application possibilities in both of these evolving markets.

REFERENCES

(1) C.O. Brady and D. L. Luck, "The Increased Use of Gas Turbines as Commercial Marine Engines" ASME paper 93-GT-142 (2) D.L. Luck, "Recent Gas Turbine Applications in Large Commercial Vessels" ASME paper 94-GT-120 (3) Carl Brady and David Luck, "Aeroderivative Gas Turbine Cruise Ship Power System Update", proceedings of Cruise and Ferry 97 conference (4) Carl 0. Brady, "LM2500 Marine Gas Turbine Sealift Program Uprate", ASME paper 94-GT-498 (5) Robert E. Reid and John J. Hartranft, "GE LM2500 Marine Gas Turbine Experience Update", ASME paper 91-GT-23 (6) F. G. Haaser, "Developing the LM2500+: Improving the LM2500 for Customer Needs", IGTI-Vol. 9, ASME COGEN- TURBO ASME 1994 (7) P. A. Dupuy, "Combined Diesel and LM2500 Gas Turbine Propulsion Enhances Corvette/Frigate Missions", July 1984 vol. 106. Journal of Engineering for Gas Turbines and Power

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