Structural Analysis and Life Prediction for Ceramic Gas Turbine Components for the Mercedes-Benz Research Car 2000

The paper considers the design and the application of ceramic components in a high temperature gas turbine, which is being developed as an alternative for passenger-car propulsion. Silicon nitride turbine wheels were analyzed using 3-dimensional finite element methods. Calculations of temperatures and stresses were carried out for several steady-state and transient load conditions. Time dependent reliability was also computed using the theory of Weibull including subcritical crack growth. The results of these calculations are presented and discussed. The basic theory for ceramic life prediction methodology is reviewed, including the relative importance of various parameters. From the results, conclusions are derived for ceramic design. Finally some operating-experiences of ceramic turbine wheels are reported.

John Deere Score™ Engines in Marine Applications

The paper gives a basic description of the stratified charge combustion process in the Stratified Charge Omnivorous Rotary Engine - SCORE. The inherent advantages of the Wankel geometry combined with spark ignition of a stratified mixture for a unique combustion cycle are explained with diagrams. The discussion points out why the engine is neither octane or cetane sensitive, making it a truly multifuel (omnivorous) intermittent combustion engine. A brief description of the parts and their function help to explain the inherent compactness of the engine and confirm its simplicity and efficiency. The engine specific size, weight, air flow and fuel flow are compared to an equivalent output turbine engine to place the performance in a familiar context. A most impressive feature of the engine, attractive cost of production, is demonstrated by the modular nature of its design. This feature is amplified by an in-depth description of the “Family of Engines” concept, highlighting the large number of common parts in a family of one to six rotor models. The ability to cover a complete market segment with one geometry is attractive for production costs, service, training and logistics. Modular design also enhances application flexibility. Development programs are underway for a diversity of applications for families of SCORE engines. Each application utilizes the unique characteristics available with this engine and is further justified by the economies realized in volume production. Thus low volume, high power applications (1000kW and up) can realize savings by utilizing the same major parts tooled for higher volume use in smaller engines. Some potential applications are discussed with particular emphasis on marine installations. Specific comparisons with other powerplants for shipboard electrical generation are presented.

The Allison 570/571 Gas Turbine for Patrol Boat Power

This paper discusses the use of 570/571-KF engine in patrol boat propulsion applications. The text is composed of two basic sections — 1. The Engine, and 2. The Applications: The engine section includes a brief review of the background and development of this free turbine engine, as well as a description of the main components and design features. The performance characteristics and fuel consumption rates are discussed relative to patrol missions. In the applications section a comparison is made of the current 570 installations (both civil and military), along with a survey of the planned applications. Finally a review of proposed uses of these engines in other naval vessels is included to show the adaptability of this size engine in FPB and PB missions, and demonstrate the feasibility of retrofitting other turbine or diesel powered patrol boats with 570/571-KF engines. The conclusion is drawn that for patrol boats with conventional or modified hull forms, the Allison 570/571 engines are well suited due to their excellent performance and power density ratios.

Durability and Damage Tolerance Assessment of the TF34-100 Engine

The critical nature of the TF34-100 engine to the Air Force’s A-10 Close Air Support weapon system made it important to obtain the best possible visibility of the engine’s future structural maintenance needs and component life limits. Accordingly, an in-depth structural durability and damage tolerance assessment was performed on this engine by a joint Air Force/General Electric team. Results of the assessment team’s unprecedented analysis efforts culminated in a comprehensive Structural Maintenance Plan that identified both current and future maintenance actions necessary for insuring maximum flight safety. The plan entailed component inspection and replacement intervals, inspection systems, preferred modifications/reworks, and a life growth plan for extending the useful life of the TF34-100 upwards to 8000 A-10 mission hours. This paper details the nature and extent of effort undertaken in conducting the 18 month structural assessment.

AGT101 Advanced Gas Turbine Technology Update

The Garrett/Ford Advanced Gas Turbine Technology Development Program, designated AGT101, has made significant progress during 1985 encompassing ceramic engine and ceramic component testing. Engine testing has included full speed operation to 100,000 rpm and 1149C (2100F) turbine inlet temperature, initial baseline performance mapping and ceramic combustor start and steady state operation. Over 380 hours of test time have been accumulated on four development engines. High temperature foil bearing coatings have passed rig test and a thick precious metal foil coating selected for engine evaluation. Ceramic structures have been successfully rig tested at 1371C (2500F) for over 27 hours. Interface compatibility testing conducted during these runs indicate RBSN-to-RBSN or SASC-to-SASC result in “sticking” — however, RBSN-to-SASC in either planar or line contact show no evidence of sticking. Ceramic combustor rig tests have demonstrated acceptable lightoffs using either a conventional ignitor or a commercially available glow plug. Operation to 1371C (2500F) combustor discharge temperatures have also been demonstrated. Ceramic turbine rotor fabrication efforts have continued at ACC and Ford. Kyocera and NGK-Locke also have been working on the rotor. Several rotors have been received and are currently undergoing final machining and qualification tests. Testing of the all-ceramic AGT101 engine is currently scheduled for late 1985.

Study and Experiments of a Small Radial Turbine for Auxiliary Power Units

The design of a small inward flow turbine with a 3.6 expansion ratio has been undertaken by MICROTURBO, in cooperation with ONERA for calculations and test results analysis. Initially, the purpose and constraints of this study are underlined. Preliminary calculations have led to the design of the blade shape of the Nozzle Guide Vane and of the rotor. Following this, the results of the quasi-3D-flow computations, performed for the stator and the rotor, are given. Both the cold bench tests on this turbine and the corresponding hot tests on the turboshaft engine enable performances to be checked. The value of the calculations is confirmed when we look at the high total and static adiabatic efficiencies obtained. These good results are encouraging for the future use of this kind of turbomachine.

The GTCP36-300, a Gas Turbine Auxiliary Power Unit for Advanced Technology Transport Aircraft

The Garrett GTCP36-300 Series Auxiliary Power Unit is being developed for use on advanced technology transport aircraft in the 150-passenger size class. The first application will be the Airbus Industries A320 Aircraft. The APU uses a 6:1 pressure ratio, single-stage compressor and turbine, driving a single-stage load compressor and accessory gearbox. The 480 horsepower APU delivers compressed air to the aircraft pneumatic system and drives a customer furnished 90 kva, 24,000 rpm electrical generator. State-of-the-art aerodynamics, materials, and digital electronics are used to give the user-airlines an APU delivering maximum performance with minimum envelope, weight, and cost of ownership.

NDT of Injection Molded Green and Sintered SiC Turbine Parts

Nondestructive evaluation of ceramic turbine components has to give special consideration to geometrical as well as to material requirements of these parts. Test procedures have to be able to detect all essential defects. As present X-ray penetration, especially the microfocus technique, is the most promising examination routine for special ceramics of complex shape. Actual developments discussed, include the use of image intersifiers for real time monitoring and utilization of digital image processing to increase defect detectability, to decrease costs and to fabricate ceramic turbine parts of higher reliability.

Engine Component Life Prediction Methodology for Conceptual Design Investigations

The increasing emphasis on engine durability requires that an analytical capability be acquired to assess engine component lives during the conceptual/preliminary design phases. A generalized methodology has been developed to provide a fundamental understanding of the impact of engine design decisions, material selections, and a detailed consideration of engine usage for critical gas turbine engine components.

Intercooled/Recuperated Shipboard Generator Drive Engine

Adverse consequences of losing electrical power to complex electronic and fire control equipment, or of the sudden variations of shore power, cause naval combatants to operate two generators most of the time, each at light load where specific fuel consumption of simple-cycle gas turbines is particularly high. The recuperated gas turbine with variable power-turbine nozzles has a much better specific fuel consumption, especially at part load. Herein described is a compact recuperated gas turbine with variable power-turbine nozzles designed for marine and industrial use, suitable with or without intercooling. These features yield a specific fuel consumption that is comparable to marine diesels used for generator drive, and essentially flat across the entire usable load range.