Test Experience With Turbine-End Foil Bearing Equipped Gas Turbine Engines

The Garrett Turbine Engine Company, a Division of the Garrett Corporation, authorized under Air Force Contract F33615-78-C-2044 and Navy Contract N00140-79-C-1294, has been conducting development work on the application of gas-lubricated hydrodynamic journal foil bearings to the turbine end of gas turbine engines. Program efforts are directed at providing the technology base necessary to utilize high-temperature foil bearings in future gas turbine engines. The main thrust of these programs was to incorporate the designed bearings, developed in test rigs, into test engines for evaluation of bearing and rotor system performance. The engine test programs included a full range of operational tests; engine thermal environment, endurance, start/stops, attitude, environmental temperatures and pressures, and simulated maneuver bearing loadings. An 88.9 mm (3.5-inch) diameter journal foil bearing, operating at 4063 RAD/SEC (38,800 rpm), has undergone test in a Garrett GTCP165 auxiliary power unit. A 44.4 mm (1.75-inch) diameter journal foil bearing, operating at 6545 RAD/SEC (62,500 rpm) has undergone test in the gas generator of the Garrett Model JFS190. This paper describes the engine test experience with these bearings.

Gas Turbine Power Systems for Military Tracked Vehicles

The gas turbine engine has been examined as a power plant for military tracked vehicles for over 30 years. Advocates have stressed the potentially high power density and high reliability as factors in favor of the turbine. Several turbine engines have been evaluated experimentally in military tracked vehicles resulting in a better understanding of such aspects as response characteristics and air inlet filtration requirements. Moreover, although the small volume and light weight of aircraft derivative gas turbines have certain virtues, it generally has been concluded that some form of waste heat recuperation is essential to achieve an acceptable level of fuel consumption, despite the increased weight and volume incurred. The selection of the AVCO Lycoming AGT1500 recuperated gas turbine as the power unit for the U.S. Army new M1 “Abrams” main battle tank was a major milestone in the evolution of gas turbine engines for tank propulsion.

Component Qualification and Initial Build of the AGT 100 Advanced Automotive Gas Turbine

In advance of initial dynamometer testing of the AGT 100 engine, all prime components and subsystems were bench/rig tested. Included were compressor, combustor, turbines, regenerator, ceramic components, and electronic control system. Results are briefly reviewed. Initial engine buildup was completed and rolled-out for test cell installation in July 1982. Shakedown testing included motoring and sequential firing of the combustor’s three fuel nozzles.

STOL Fighter Technology Program

In recent years, the Air Force has provided additional funds to investigate the technologies and problems associated with providing fighters a Short Take Off and Landing (STOL) capability without seriously degrading today’s maneuver, load, and cruise performance. Within the Flight Dynamics Laboratory, this technology thrust has been planned and organized under the title of “Runway Independence.” The thrust is multi-disciplined in that the following technologies are being investigated both singularly and in integrated combinations to quantify their contribution to providing options in solving the STOL design task. These technologies are: aerodynamics, integrated controls, thrust vectoring/reversing exhaust nozzles, landing gear, and cockpit aids and controllers necessary to operate under weather and/or at night. To help focus these technology efforts and to mature existing technology, the STOL Technology Fighter program was formulated. The objective of the program is to flight validate and mature near-term advanced technologies applicable to providing a STOL capability without sacrificing today’s maneuver, cruise or dash performance. Specific technologies to be addressed in this program are: two-dimensional thrust vectoring/reversing exhaust nozzle; integrated flight/propulsion control; advanced high lift systems; rough/soft field landing gear; and cockpit aids and controllers necessary to locate and land a fighter on the usable portion of the runway at night and in weather. The program will either modify an existing fighter like the F-15, F-16 or F-18 or build a hybrid vehicle like the X-29 with these technologies integrated into the vehicle. The contract will be awarded in 1983 with first flight in late 1987. The end objective of the program is to demonstrate take offs and landings under wet runway conditions of under 1500 feet including dispersion. This paper discusses the integration of these technologies into a total flight program.

EAGLE/DTA: A Life Cycle Cost Model for Damage Tolerance Assessment

The U.S. Air Force and Pratt & Whitney Aircraft are currently engaged in developing technology to minimize low-cycle fatigue maintenance requirements in future gas turbine engines. The Life Cycle Cost/Damage Tolerance Assessment (LCC/DTA) program is directed toward furthering technology development in two important areas that relate to the overall life cycle cost of advanced Air Force weapon systems: life cycle cost modeling and analysis, and damage tolerance design (DTD). A major goal of the LCC/DTA program is to establish hot-section disk design criteria specifying acceptable levels for life and maintenance actions based on minimum life cycle cost. This paper discusses the methodology developed to evaluate the weapon system LCC impact of designing to damage tolerance criteria.

Danish Navy Experience With the KV-72 LM2500 CODOG Propulsion Plant

For more than twenty years the Royal Danish Navy (RDN) has been using gas turbine engines for propulsion of fast patrol vessels as well as frigates. This paper, which is the result of a joint effort by the Royal Danish Navy, Aalborg Vaerft Shipyard, and General Electric Company USA, describes how the propulsion system design was developed using previous RDN gas turbine system experience. A detailed description of the ship, the selection of machinery, and design of the propulsion configuration, including the LM2500 gas turbine module, is included. The three Royal Danish “KV-72” corvettes of the NIELS JUEL class have now been in operation for almost three years. Since the start-up of the NIELS JUEL machinery in November 1978 the CODOG propulsion plants aboard this class have accumulated more than 8,000 running hours, of which over 1,500 hours have been in the gas turbine or “sprint” drive mode. Operational experience with the GE LM2500 gas turbines is also described.

The Impact of Computers on the Test Cell of Tomorrow

Rapidly increasing fuel costs, the increasing complexity of the new engines now available, along with the inaccuracies, inefficiencies and long test cycles inherent in manual testing push the cost of engine testing to unnecessary levels. One promising avenue of relief is the automation of gas turbine testing through the use of real-time computer data acquisition and processing systems. Remarkable progress has been made in the area of closed-loop or fully automatic operation of the test process from start-up using various programmable steps, recording results as dictated by the test procedure, controlling operation and a safe engine shut down. This paper discusses the successful application of a real-time computer system with both closed and open-loop capabilities. This particular system called “ADAPS™” (Automatic Data Acquisition and Processing System) handled its first 3,000 hours of engine operation without a single hardware or software interruption. Savings in manpower alone in that period was nearly 18,000 man-hours.

Computer Systems: An Aid to the Development of Gas Turbine Engines

This paper presents a concept as to the stepwise extension of computer-systems application by KHD Luftfahrttechnik’s engineering departments engaged in gas turbine engine development. A base line system is in used today and criteria have been established to expand this into an efficient engineering tool. Discussed are the principle conditions and targets including items such as cost effectiveness, data communications between different departments, programming, personnel training as well as data analysis and requirements for soft and hardware.

Royal Naval Marine Gas Turbines in the South Atlantic in 1982

The Royal Navy has now over 20 operational gas turbine powered warships, the majority with a two Olympus/two Tyne COGOG main propulsion fit. Many of these were deployed in the South Atlantic during the Falklands crisis in the Spring of 1982. The paper analyses the lessons learnt during 4 months of strenuous operations in a hostile environment.

Aircraft Usage and Effects on Engine Life

Factors which affect engine life include design practices, manufacturing processes, materials, engine installations, usage, and maintenance system practices. While engine life definition and management are dependent upon the development and organization of these factors, aircraft engine power usage is a major factor affecting engine life in field operations. This statement is based upon an improved understanding of engine usage as functions of aircraft characteristics and the nature of missions which are flown. Increasing amounts of data have been acquired in recent years that provide insights into the magnitude and variability of engine life for several aircraft systems. This paper will compare aircraft usage and engine life relationships for representative aircraft systems. An outline of procedures used to evaluate engine usage and its effects shall also be presented.