Directions in High Temperature Intermetallics Research

1988 ◽  
Vol 133 ◽  
Author(s):  
Dennis M. Dimiduk ◽  
Daniel B. Miracle
Keyword(s):  
High Temperature ◽  
Air Force ◽  
Evolutionary Process ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Paper Briefly ◽  
Research Directions ◽  
Intermetallic Materials ◽  
Turbine Performance ◽  
Structural Intermetallic

ABSTRACTStructural intermetallic materials have undergone an evolutionary process whereby some of the materials could provide major payoffs in gas turbine engines. This maturation of select intermetallic systems has provided significant hope for making still greater advances in turbine performance through further developments in other intermetallic materials. The same maturation process has highlighted specific limitations and requirements which are key to the utilization of intermetallic systems. This paper briefly reviews some critical ground rules for high temperature intermetallics development and identifies research directions being pursued by the Air Force for advancing intermetallic materials.

HAYNES ALLOY 75

Alloy Digest ◽  
1999 ◽  
Vol 48 (7) ◽  
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Heat Treating ◽  
Turbine Engines ◽  
Chromium Alloy ◽  
Gas Turbine Engines ◽  
Typical Application ◽  
Good Oxidation Resistance ◽  
Temperature Performance ◽  
Haynes Alloy

Abstract Haynes alloy 75 is an 80 nickel-20 chromium alloy with both good oxidation resistance and good mechanical properties at high temperatures. It is amenable to all forms of fabrication and welding. A typical application for sheet metal is fabrications in gas turbine engines. This datasheet provides information on composition, physical properties, elasticity, and tensile properties as well as creep. It also includes information on high temperature performance as well as forming and heat treating. Filing Code: Ni-557. Producer or source: Haynes International Inc.

On the Integration of Hot Foil Bearings Into Gas Turbine Engines: Theoretical Treatment

2019 ◽  
Author(s):  
Hooshang Heshmat ◽  
James F. Walton
Keyword(s):  
High Temperature ◽  
System Dynamics ◽  
High Performance ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Structural Stiffness ◽  
Foil Bearings ◽  
Foil Bearing ◽  
High Temperature Operation ◽  
Bearing System

Abstract To achieve high power density Gas Turbine Engines (GTEs), R&D efforts have strived to develop machines that spin faster and run hotter. One method to achieve that goal is to use high temperature capable foil bearings. In order to successfully integrate these advanced foil bearings into GTE systems, a theoretical understanding of both bearing and rotor system integration is essential. Without a fundamental understanding and sound theoretical modeling of the foil bearing coupled with the rotating system such an approach would prove application efforts fruitless. It is hoped that the information provided in this paper will open up opportunistic doors to designs presently thought to be impossible. In this paper an attempt is made to describe how an advanced foil bearing is modeled for extreme high temperature operation in high performance turbomachinery including GTEs, Supercritical CO2 turbine generators and others. The authors present the advances in foil bearing capabilities that were crucial to achieving high temperature operation. Achieving high performance in a compliant foil bearing under the wide extremes of operating temperatures, pressures and speeds, requires a bearing system design approach that accounts for the highly interrelated compliant surface foil bearing elements such as: the structural stiffness and frictional characteristics of the underlying compliant support structure across the operating temperature and pressure spectrum; and the coupled interaction of the structural elements with the hydrodynamic pressure generation. This coupled elasto-hydrodynamic-Finite Element highly non-linear iterative methodology will be used by the authors to present a series of foil bearing design evaluations analyzing and modeling the foil bearing under extreme conditions. The complexity of the problem of achieving foil bearing system operation beyond 870°C (1600°F) requires as a prerequisite the attention to the tribological details of the foil bearing. For example, it is necessary to establish how both the frictional and viscous damping coefficient elements as well as the structural and hydrodynamic stiffness are to be combined. By combining these characteristics the influence of frictional coefficients of the elastic and an-elastic materials on bearing structural stiffness and hence the bearing effective coupled elasto-hydrodynamic stiffness coefficients will be shown. Given that the bearing dynamic parameters — stiffness and damping coefficients — play a major role in the control of system dynamics, the design approach to successfully integrate compliant foil bearings into complex rotating machinery systems operating in extreme environments is explored by investigating the effects of these types of conditions on rotor-bearing system dynamics. The proposed rotor/bearing model is presented to describe how system dynamics and bearing structural properties and operating characteristics are inextricably linked together in a manner that results in a series separate but intertwined iterative solutions. Finally, the advanced foil bearing modeling and formulation in connection with resulting rotor dynamics of the system will be carried out for an experimental GTE simulator test rig. The analytical results will be compared with the experiments as presented previously to demonstrate the effectiveness of the developed method in a real world application [1].

scholarly journals Some Aerodynamic Problems of Aircraft Engines: Fifty Years After -The 2007 IGTI Scholar Lecture-

2009 ◽  
Vol 131 (3) ◽  
Author(s):  
Edward M. Greitzer
Keyword(s):  
Gas Turbine ◽  
Collaborative Research ◽  
Research Process ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Aircraft Engines ◽  
Jet Engines ◽  
Organizational Boundaries ◽  
Turbine Performance ◽  
Single Discipline

Problems of high technological interest, for example the development of gas turbine engines, span disciplinary, and often organizational, boundaries. Although collaboration is critical in advancing the technology, it has been less a factor in gas turbine research. In this paper it is proposed that step changes in gas turbine performance can emerge from collaborative research endeavors that involve the development of integrated teams with the needed range of skills. Such teams are an important aspect in product development, but they are less familiar and less subscribed to in the research community. The case histories of two projects are given to illustrate the point: the development of the concept of “smart jet engines” and the Silent Aircraft Initiative. In addition to providing a capability to attack multidisciplinary problems, the way in which collaboration can enhance the research process within a single discipline is also discussed.

scholarly journals Development of New C&W Superalloys for High Temperature Disk Applications

2011 ◽  
Vol 278 ◽  
pp. 405-410 ◽  
Author(s):  
Alexander Devaux ◽  
Eric Georges ◽  
Philippe Héritier
Keyword(s):  
Phase Diagram ◽  
High Temperature ◽  
Cobalt Content ◽  
Industrial Processes ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Creep Properties ◽  
Disk Alloy ◽  
Nickel Base ◽  
Moderate Cost

The enhancement of efficiency in gas turbine engines requires the development of new superalloys capable of withstanding higher temperatures. The development of novel industrial cast and wrought (C&W) disk alloys with required combination of strength, creep and fatigue resistances at 700°C is particularly desired due to the expensive cost of powder metallurgy. In this context, new C&W disk alloys were recently developed to fulfill these requirements. TMW4 shows higher properties than the current C&W disk alloy despite an expensive cost due to its high cobalt content, where as 718Plus presents a moderate cost with restricted creep properties at 700°C compared to the current U720Li disk alloy. The new nickel base superalloys developed by Aubert & Duval were therefore designed to offer a better compromise between high temperature properties at 700°C and cost. This paper describes the alloy metallurgical features and is especially focused on the alloy design which is extensively based on phase diagram modeling. The study was firstly carried out on small ingots of 6 kg to optimize the chemistry before forging 200 kg ingots by industrial processes. The ability to be processed by the conventional cast & wrought route and the control of the highly expensive elements contents confer to the alloys an attractive cost comparable to that of 718Plus alloy. The high amount of ’ and the molybdenum-tungsten levels insure higher creep and tensile properties than those obtained with 718Plus.

scholarly journals The Basics of Powder Lubrication in High-Temperature Powder-Lubricated Dampers

1991 ◽  
Author(s):  
Hooshang Heshmat ◽  
James F. Walton
Keyword(s):  
High Temperature ◽  
High Speed ◽  
Basic Mechanism ◽  
Test Facility ◽  
Experimental Program ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Powder Lubrication ◽  
Basic Features ◽  
Selection Of

The objective of this investigation is to develop a novel powder-lubricated rotor bearing system damper concept for use in high-temperature, high-speed rotating machinery such as advanced aircraft gas turbine engines. The approach discussed herein consists of replacing a conventional oil lubrication or frictional damper system with a powder lubrication system that uses the process particulates or externally-fed powder lubricant. Unlike previous work in this field, this approach is based on the postulate of the quasi-hydrodynamic nature of powder lubrication. This postulate is deduced from past observation and present verification that there are a number of basic features of powder flow in narrow interfaces that have the characteristic behavior of fluid film lubrication. In addition to corroborating the basic mechanism of powder lubrication, the conceptual and experimental work performed in this program provides guidelines for selection of the proper geometries, materials and powders suitable for this tribological process. The present investigation describes the fundamentals of quasi-hydrodynamic powder lubrication and defines the rationale underlying the design of the test facility. The performance and the results of the experimental program present conclusions reached regarding design requirements as well as the formulation of a proper model of quasi-hydrodynamic powder lubrication.

Moisture Condensation Effect on Turbine Performance Tests

2004 ◽  
Author(s):  
I. Roumeliotis ◽  
K. Mathioudakis
Keyword(s):  
Turbine Engines ◽  
Performance Tests ◽  
Gas Turbine Engines ◽  
Performance Parameters ◽  
Atmospheric Air ◽  
Turbine Performance ◽  
Working Medium ◽  
Component Test ◽  
Moisture Condensation ◽  
Condensation Effect

Water is always present in the atmospheric air in the form of vapour, affecting the operation of turbomachinery components in gas turbine engines. Due to water presence in the working medium, condensation may occur, which can influence the thermal performance of the component and alter the measurements taken for calculations. This can lead to erroneous evaluation of component performance parameters during development performance tests. Procedures to detect condensation and if possible to correct the measurements during engine or component test should be used to avoid such situations. A method allowing the prediction of condensation and the correction of the measurements for low speed expansion is presented. The method is implemented in turbine testing measurements where condensation occurs and the results show that condensation may be predicted and its effects corrected.

Future Research Directions for Ship Propulsion Materials

2009 ◽  
Author(s):  
David A. Shifler
Keyword(s):  
High Temperature ◽  
Gas Turbine ◽  
Fuel Efficiency ◽  
High Strength ◽  
Turbine Engines ◽  
Future Research ◽  
Oxide Surface ◽  
Materials Testing ◽  
Gas Turbine Engines ◽  
Protective Oxide

High temperature applications demand materials that have a variety of properties such as high strength, toughness, creep resistance, fatigue resistance, as well as resistance to degradation by their interaction with the environment. All potential metallic materials are unstable in many high temperatures environments without the presence of a protective coating on the component surface. High temperature alloys derive their resistance to degradation by forming and maintaining a continuous protective oxide surface layer that is slow-growing, very stable, and adherent. In aggressive environments, the superalloy oxidation and corrosion resistance needs to be augmented by coatings. Propulsion materials for Naval shipboard gas turbine engines are subjected to the corrosive environment of the sea to differing degrees. Increasing fuel efficiency and platform capabilities require higher operating temperatures that may lead to new degradation modes of coatings and materials. Fuel contaminants or the lack of contaminants from alternative synthetic fuels may also strongly influence coating and/or materials performance which, in turn, can adversely affect the life in these propulsion or auxiliary gas turbine engines. This paper will dwell on some past results of materials testing and offer some views on future directions into materials research in high temperature materials in aggressive environments that will lead to new advanced propulsion materials for shipboard applications.

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