Experience in Extending the Life of Gas Turbine Blades

This paper presents the effects of deterioration of gas turbine blade life with prolonged service exposure. This deterioration is primarily due to internal microstructural changes and the formation of creep voids or cavitation. Methods of evaluating residual blade life or life trend curves are presented along with a documentation of the creep damage observed. The extension of blade life by Hot isostatic pressing versus reheat treatment is discussed and data is presented to show that complete recovery of properties can be achieved even after the material has suffered extensive internal creep damage. As a result, the time between overhauls for blades can be significantly extended, and the need for replacement blades can be minimized.

A Gas Turbine Maintenance Information System for the Saudi Arabian East-West Crude Oil Pipeline

The 747-mile East-West Crude Oil Pipeline across Saudi Arabia employs 60 gas turbines for pumping and power generation. Mainline pump drives are three United Technologies Corporation FT4A-9 modular industrial gas turbines at each of 11 pumping stations. Two of the three mainline gas turbines are required for maximum throughput, while the third is an operational spare. High reliability and availability constraints and the remote unmanned station concept underscore the need for a modern maintenance information system. This paper describes an independent multiple-fault diagnostic/prognostic system, employing a patented gas path analysis technique.

Future Trends in Subsonic Transport Energy Efficient Turbofan Engines

Details of the NASA sponsored General Electric Energy Efficient Engine (E3) technology program are presented along with a description of the engine, cycle and aircraft system benefits. Opportunities for further performance improvement beyond E3 are examined. Studies leading to the selection of the E3 cycle and configuration are summarized. The advanced technology features, cycle and component performance levels are also presented. An evaluation of the benefits of the fully developed Flight Propulsion System (FPS) is made relative to the NASA program goals by comparing the FPS with the CF6-50C where both are installed in advanced subsonic transport aircraft. Results indicate that a mission fuel saving from 15 to 23 percent is possible depending on mission length.

Gas Turbine Propulsion Systems for Small Naval Ships

Analysis of gas turbine-powered naval ships of 500- to 4000-ton size has been performed for ocean escort and patrol missions with performance levels appropriate to gas turbines of both current and advanced technology. The use of gas turbine systems allows the realization of high mission effectiveness with relatively small ships. For advanced marine gas turbines, the most significant ship benefit would result from increased thermal efficiency of cruise engines by means of regenerative cycles. A secondary improvement, particularly for high dash speeds, would be the reduction of specific weight for dash engines. With such advanced gas turbines, ship sizes may be further reduced for given mission capabilities.

Development of a Coal Fired Pressurized Fluidized Bed for Combined Cycle Power Generation

A program to design, construct and operate a pilot electric plant using a pressurized fluidized bed (PFB) combustor burning high sulfur coal to produce electricity at competitive costs and in an environmentally acceptable manner is proceeding under DOE sponsorship. Three components were identified needing experimental test data to validate the selected design configurations or material selections. These components included: (a) PFB in-bed heat exchanger tubes, (b) hot gas cleanup system, and (c) turbine blades. R&D test programs utilizing laboratory rigs, commercial fluid bed reactors, and a large scale PFB technology rig were conducted for a cumulative test time of over 10,000 hr. Design criteria and configurations were selected and verified. This paper presents the results of the technology development presents the results of the technology development tests. Also, the large scale PFB technology rig design and test program are presented. The results of operating a small gas turbine coupled to the PFB combustor and hot gas cleanup system within this technology rig are discussed.

Existing Military Trainer Engine Designed to Achieve Low Maintenance Cost

The LARZAC 04 turbofan engine has been designed, developed and qualified by two French gas turbine engine companies linked by a controlling group known as Groupement Turbomeca-SNECMA. The LARZAC engine is in production for the Alpha Jet, a military aircraft developed by Avions Marcel Dassault-Breguet Aviation and Dornier GmbH. Teledyne CAE has an agreement to market, service and, optionally, to manufacture the LARZAC 04 in the United States and Canada and has designated this engine the Model 490-4. This paper addresses the criteria used to design the Model 490-4 and achieve high reliability and low maintenance cost. For example: (a) modular construction and how it reduces maintenance cost, (b) high reliability design and its payoff in low maintenance costs, and (c) the planned growth of the inspection intervals to achieve minimum Life Cycle Cost. Also addressed in this paper is the rugged design of the engine as proven by cyclic component tests, large and small bird ingestion, water and hail ingestion, short cycle testing and Simulated Mission Endurance Tests.

Design and Test of a 73-MW Water Cooled Gas Turbine

This paper presents a preliminary design of a water-cooled gas turbine capable of operating on coal derived fuels and producing 73 MW when burning low Btu coal gas. Particular emphasis is placed on the critical technology issues of combustion and heat transfer at 2600 deg firing temperature. The recent technology developments; i.e., materials developments, composite construction, water cooling, fuels cleanup, etc., which now make this advanced concept possible are discussed. Detailed descriptions of the hot gas path components, the staged sectoral combustor, the water cooled nozzles and buckets, are described showing the implementation of these recent developments. The component development test program which is underway, is described and where testing results are available, design confirmation is demonstrated. Future plans for the construction of a full scale prototype machine and for design verification testing are presented. An analytical evaluation is included which demonstrates the advantages of the water-cooled gas turbine in an integrated gasification combined cycle.

Testing of Ceramic Rotors: Hot Spin Test Rig and Rotor Preparation

A series of duo-density silicon nitride gas turbine rotors have been prepared for testing and tested at Ford Motor Company. The paper reviews the duo-density fabrication process, and covers in detail the rotor preparation process, which includes machining, inspection, and cold proof spinning. The paper describes the hot spin test rig used for the hot testing of the rotors, and summarizes the results of the hot spin test program.

Elastomer Damper Performance: A Comparison With a Squeeze Film for a Supercritical Power Transmission Shaft

This paper describes the design and testing of an elastomer damper on a super-critical power transmission shaft. The elastomers were designed to provide acceptable operation through the fourth bending mode and to control synchronous as well as nonsynchronous vibration throughout the operating range. The design of the elastomer was such that it could be incorporated into the system as a replacement for a squeeze-film damper without a reassembly, which could have altered the imbalance of the shaft. This provided a direct comparison of the elastomer and squeeze-film dampers without having to assess the effect of shaft imbalance changes.

Gas Turbine Engine Disk Retirement-for-Cause: An Application of Fracture Mechanics and NDE

Historically, gas turbine engine disks are retired when they accrue an analytically determined lifetime where the first fatigue crack per 1000 disks could be expected. By definition then, 99.9 percent of these components are being retired prematurely. Retirement-for-Cause (RFC) is a procedure, based on Fracture Mechanics, which would allow safe utilization of the full life capacities of each individual disk. Since gas turbine disks are among the most costly of engine components, adopting a RFC philosophy could result in substantial systems life cycle cost savings. These would accrue from reduced replacement costs, conservation of strategic materials such as cobalt, and energy savings.