| A Three-Dimensional Foil Bearing Performance Map Applied to Oil-Free Turbomachinery |
Apr-2009 |
22 pages |
| Authors:
Christopher Dellacorte; Kevin C Radil; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH GLENN RESEARCH CENTER
|
 | To effectively apply compliant foil gas bearings to increasingly larger and more challenging turbomachinery, a comprehensive method that compares a foil bearing's capabilities with the application's operating requirements is needed. Extensive laboratory and field experience suggests foil bearing failure is generally due to thermal stress brought on by excessive viscous power loss; therefore a map that graphically relates component and system-level parameters (bearing size, applied loads, and shaft rotational speeds) ... |
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| Moisture-Induced Delayed Alumina Scale Spallation on a Ni(Pt)Al Coating (Preprint) |
Apr-2009 |
32 pages |
| Authors:
James L Smialek; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH GLENN RESEARCH CENTER
|
| Delayed scale failure was examined for samples of a Ni(Pt)Al-coated CMSX4 single crystal superalloy, cyclically oxidized at 1150 degrees C for 2000 hr. One sample exhibited accentuated coating grain boundary wrinkling, initiating local alumina scale spallation to bare metal, resulting in a final weight loss of 3.3 milligrams/(square centimeter). Spallation under ambient conditions was monitored with time after cooldown and was found to continue for times up to 24 hr, ... |
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| A Survey of Intelligent Control and Health Management Technologies for Aircraft Propulsion Systems |
MAY 2005 |
26 pages |
| Authors:
Jonathan S. Litt; Donald L. Simon; Sanjay Garg; Ten- Heui Guo; Carolyn Mercer; Richard Miller; Alireza Behbahani; Anupa Bahwa; Daniel T. Jensen; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH GLENN RESEARCH CENTER
|
| Intelligent Control and Health Management technology for aircraft propulsion systems is much more developed in the laboratory than in practice. With a renewed emphasis on reducing engine life cycle costs, improving fuel efficiency, increasing durability and life, etc., driven by various government programs, there is a strong push to move these technologies out of the laboratory and onto the engine. This paper describes the existing state of engine control and ... |
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| Advanced Oxide Material Systems for 1650 Deg. C Thermal/Environmental Barrier Coating Applications |
DEC 2004 |
13 pages |
| Authors:
Dongming Zhu; Dennis S. Fox; Narottam P. Bansal; Robert A. Miller; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH GLENN RESEARCH CENTER
|
| Advanced thermal and environmental barrier coatings (TEBCs) are being developed for low- emission SiC/SiC ceramic matrix composite (CMC) combustor and vane applications to extend the CMC liner and vane temperature capability to 1650 degrees C (3000 degrees F) in oxidizing and water-vapor-containing combustion environments. The advanced 1650 degrees C TEBC system is required to have a better high temperature stability, lower thermal conductivity, and more resistance to sintering and thermal ... |
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| Intelligent, Robust Control of Deteriorated Turbofan Engines via Linear Parameter Varying Quadratic Lyapunov Function Design |
NOV 2004 |
18 pages |
| Authors:
James A. Turso; Jonathan S. Litt; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH GLENN RESEARCH CENTER
|
| A method for accommodating engine deterioration via a scheduled Linear Parameter Varying Quadratic Lyapunov Function (LPVQLF)-Based controller is presented. The LPVQLF design methodology provides a means for developing unconditionally stable, robust control of Linear Parameter Varying (LPV) systems. The controller is scheduled on the Engine Deterioration Index, a function of estimated parameters that relate to engine health, and is computed using a multilayer feed forward neural network. Acceptable thrust response ... |
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| Hierarchical Discrete Event Supervisory Control of Aircraft Propulsion Systems |
NOV 2004 |
20 pages |
| Authors:
Murat Yasar; Devendra Tolani; Asok Ray; Neerav Shah; Jonathn S. Litt; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH GLENN RESEARCH CENTER
|
| This paper presents a hierarchical application of Discrete Event Supervisory (DES) control theory for intelligent decision and control of a twin- engine aircraft propulsion system. A dual layer hierarchical DES controller is designed to supervise and coordinate the operation of two engines of the propulsion system. The two engines are individually controlled to achieve enhanced performance and reliability, necessary for fulfilling the mission objectives. Each engine is operated under a ... |
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| Experimental Investigation of Diffuser Hub Injection to Improve Centrifugal Compressor Stability |
OCT 2004 |
22 pages |
| Authors:
Gary J. Skoch; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH GLENN RESEARCH CENTER
|
| Results from a series of experiments to investigate whether centrifugal compressor stability could be improved by injecting air through the diffuser hub surface are reported. The research was conducted in a 4:1 pressure ratio centrifugal compressor configured with a vane-island diffuser. Injector nozzles were located just upstream of the leading edge of the diffuser vanes. Nozzle orientations were set to produce injected streams angled at -8,0 and +8 degrees relative ... |
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| Propulsion Control and Health Management (PCHM) Technology for Flight Test on the C-17 T-1 Aircraft |
OCT 2004 |
38 pages |
| Authors:
Donald L. Simon; Sanjay Garg; Michael Venti; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH GLENN RESEARCH CENTER
|
| The C-17 T-1 Globemaster III is an Air Force flight research vehicle located at Edwards Air Force Base. NASA Dryden and the C-17 System Program Office have entered into a Memorandum of Agreement to permit NASA the use of the C-17 T-1 to conduct flight research on a mutually coordinated schedule. The C-17 Propulsion Control and Health Management (PCHM) Working Group was formed in order to foster discussion and coordinate ... |
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| Reduced-Order Modeling and Wavelet Analysis of Turbofan Engine Structural Response Due to Foreign Object Damage (FOD) Events |
AUG 2004 |
43 pages |
| Authors:
James Turso; Charles Lawrence; Jonathan Litt; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH GLENN RESEARCH CENTER
|
| The development of a wavelet-based feature extraction technique specifically targeting FOD-event induced vibration signal changes in gas turbine engines is described. The technique performs wavelet analysis of accelerometer signals from specified locations on the engine and is shown to be robust in the presence of significant process and sensor noise. It is envisioned that the technique will be combined with Kalman filter thermal/health parameter estimation for FOD-event detection via information ... |
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| Sensor Needs for Control and Health Management of Intelligence Aircraft Engines |
AUG 2004 |
15 pages |
| Authors:
Donald L. Simon; Sanjay Garg; Gary W. Hunter; Ten- Huei Guo; Kenneth J. Semega; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH GLENN RESEARCH CENTER
|
| NASA and the U.S. Department of Defense are conducting programs which support the future vision of "intelligent" aircraft engines for enhancing the affordability, performance, operability, safety, and reliability of aircraft propulsion systems. Intelligent engines will have advanced control and health management capabilities enabling these engines to be self-diagnostic, self- prognostic, and adaptive to optimize performance based upon the current condition of the engine or the current mission of the vehicle. ... |
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| A Foreign Object Damage Event Detector Data Fusion System for Turbofan Engines |
AUG 2004 |
25 pages |
| Authors:
James A. Turso; Jonathan S. Litt; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH GLENN RESEARCH CENTER
|
| A Data Fusion System designed to provide a reliable assessment of the occurrence of Foreign Object Damage (FOD) in a turbofan engine is presented. The FOD-event feature level fusion scheme combines knowledge of shifts in engine gas path performance obtained using a Kalman filter., with bearing accelerometer signal features extracted via wavelet analysis, to positively identify a FOD event. A fuzzy inference system provides basic probability assignments (bpa) based on ... |
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| Effect of Surface Impulsive Thermal Loads on Fatigue Behavior of Constant Volume Propulsion Engine Combustor Materials |
AUG 2004 |
15 pages |
| Authors:
Dongming Zhu; Dennis S. Fox; Robert A. Miller; Louis J. Ghosn; Sreeramesh Kalluri; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH GLENN RESEARCH CENTER
|
| The development of advanced high performance constant-volume- combustion-cycle engines (CVCCE) requires robust design of the engine components that are capable of enduring harsh combustion environments under high frequency thermal and mechanical fatigue conditions. In this study, a simulated engine test rig has been established to evaluate thermal fatigue behavior of a candidate engine combustor material, Haynes 188, under superimposed CO2 laser surface impulsive thermal loads (30 to 100 Hz) in ... |
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| Evaluation of an Enhanced Bank of Kalman Filters for In-Flight Aircraft Engine Sensor Fault Diagnostics |
AUG 2004 |
16 pages |
| Authors:
Takahisa Kobayashi; Donald L. Simon; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH GLENN RESEARCH CENTER
|
| In this paper, an approach for in-flight fault detection and isolation (FDI) of aircraft engine sensors based on a bank of Kalman filters is developed. This approach utilizes multiple Kalman filters, each of which is designed based on a specific fault hypothesis. When the propulsion system experiences a fault, only one Kalman filter with the correct hypothesis is able to maintain the nominal estimation performance. Based on this knowledge, the ... |
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| Development and Fatigue Testing of Ceramic Thermal Barrier Coatings |
JUL 2004 |
15 pages |
| Authors:
Dongming Zhu; Sung R. Chol; Robert A. Miller; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH GLENN RESEARCH CENTER
|
| Ceramic thermal barrier coatings will play an increasingly important role in future gas turbine engines because of their ability to effectively protect the engine components and further raise engine temperatures. Durability of the coating systems remains a critical issue with the ever-increasing temperature requirements. Thermal conductivity increase and coating degradation due to sintering and phase changes are known to be detrimental to coating performance. There is a need to characterize ... |
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| Procedure for Determining One-Dimensional Flow Distributions in Arbitrarily Connected Passages Without the Influence of Pumping |
JUN 2004 |
10 pages |
| Authors:
Peter L. Meitner; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH GLENN RESEARCH CENTER
|
| A calculation procedure is presented which allows the one-dimensional determination of flow distributions in arbitrarily connected (branching) flow passages having multiple inlets and exits. The procedure uses an adaptation of the finite element technique, iteratively coupled with an accurate one- dimensional flow solver. The procedure eliminates the usual restrictions inherent with finite element flow calculations. Unlike existing one-dimensional methods, which require simplifications to the flow equations (uncoupling the momentum and ... |
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| Leakage and Power Loss Test Results for Competing Turbine Engine Seals |
MAY 2004 |
16 pages |
| Authors:
Margaret P. Proctor; Irebert R. Delgado; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH GLENN RESEARCH CENTER
|
| Advanced brush and finger seal technologies offer reduced leakage rates over conventional labyrinth seals used in gas turbine engines. To address engine manufacturers' concerns about the heat generation and power loss from these contacting seals, brush, finger, and labyrinth seals were tested in the NASA High Speed, High Temperature Turbine Seal Test Rig. Leakage and power loss test results are compared for these competing seals for operating conditions up to ... |
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| TF41 Engine Fan Disk Seeded Fault Crack Propagation Test |
MAY 2004 |
14 pages |
| Authors:
David G. Lewicki; William C. Emmerling; Donald Altobelli; Silvia Seng; Chuck Frankenberger; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH GLENN RESEARCH CENTER
|
| A cooperative program was conducted between the FAA, U.S. Navy, NASA, and the U.S. Air Force to evaluate crack detection techniques in a seeded fault engine test. The first stage fan of a TF41 engine with a seeded fault was run in a full scale engine test facility. Various disk crack detection systems were installed on the disk and monitored real time. Post-engine-test cycles were accumulated on the TF41 disk ... |
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| Investigation of Gear and Bearing Fatigue Damage Using Debris Particle Distributions |
MAY 2004 |
16 pages |
| Authors:
Paula J. Dempsey; David G. Lewicki; Harry J. Decker; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH GLENN RESEARCH CENTER
|
| A diagnostic tool was developed for detecting fatigue damage to spur gears, spiral bevel gears, and rolling element bearings. This diagnostic tool was developed and evaluated experimentally by collecting oil debris data from fatigue tests performed in the NASA Glenn Spur Gear Fatigue Rig, Spiral Bevel Gear Test Facility, and the 500 hp Helicopter Transmission Test Stand. During each test, data from an on-line, in-line, inductance type oil debris sensor ... |
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| An Experimental Investigation into the Temperature Profile of a Compliant Foil Air Bearing |
MAY 2004 |
20 pages |
| Authors:
Kevin Radil; Michelle Zeszotek; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH GLENN RESEARCH CENTER
|
| A series of tests was performed to determine the internal temperature profile in a compliant bump-type foil journal air bearing operating at room temperature under various speeds and load conditions. The temperature profile was collected by instrumenting a foil bearing with nine, type K thermocouples arranged in the center and along the bearing's edges in order to measure local temperatures and estimate thermal gradients in the axial and circumferential directions. ... |
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| Strain-Life Assessment of Grainex Mar-M 247 for NASA's Turbine Seal Test Facility |
APR 2004 |
12 pages |
| Authors:
Irebert R. Delgado; Gary R. Halford; Bruce M. Steinetz; Clare M. Rumnac; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH GLENN RESEARCH CENTER
|
| NASA's Turbine Seal Test Facility is used to test air-to-air seals for use primarily in advanced jet engine applications. Combinations of high temperature, high speed, and high pressure limit the disk life, due to the concern of crack initiation in the bolt holes of the Grainex Mar-M 247 disk. The primary purpose of this current work is to determine an inspection interval to ensure safe operation. The current work presents ... |
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| Development of an Information Fusion System for Engine Diagnostics and Health Management |
FEB 2004 |
22 pages |
| Authors:
Allan J. Volponi; Tom Brotherton; Robert Luppold; Donald L. Simon; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH GLENN RESEARCH CENTER
|
| Aircraft gas-turbine engine data are available from a variety of sources including on-board sensor measurements, maintenance histories, and component models. An ultimate goal of Propulsion Health Management (PHM) is to maximize the amount of meaningful information that can be extracted from disparate data sources to obtain comprehensive diagnostic and prognostic knowledge regarding the health of the engine. Data Fusion is the integration of data or information from multiple sources, to ... |
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| Application of a Bank of Kalman Filters for Aircraft Engine Fault Diagnostics |
AUG 2003 |
15 pages |
| Authors:
Takahisa Kobayashi; Donald L. Simon; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH GLENN RESEARCH CENTER
|
| In this paper, a bank of Kalman filters is applied to aircraft gas turbine engine sensor and actuator fault detection and isolation (FDI) in conjunction with the detection of component faults. This approach uses multiple Kalman filters, each of which is designed for detecting a specific sensor or actuator fault. In the event that a fault does occur, all filters except the one using the correct hypothesis will produce large ... |
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| Aircraft Turbofan Engine Health Estimation Using Constrained Kalman Filtering |
AUG 2003 |
13 pages |
| Authors:
Dan Simon; Donald L. Simon; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH GLENN RESEARCH CENTER
|
| Kalman filters are often used to estimate the state variables of a dynamic system. However, in the application of Kalman filters some known signal information is often either ignored or dealt with heuristically. For instance, state variable constraints (which may be based on physical considerations) are often neglected because they do not fit easily into the structure of the Kalman filter. This paper develops an analytic method of incorporating state ... |
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| Design and Fabrication of High-Temperature, Radial Magnetic Bearing for Turbomachinery |
JUL 2003 |
18 pages |
| Authors:
Gerald Montague; Mark Jansen; Ben Ebihara; Ralph Jansen; Alan Palazzolo; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH GLENN RESEARCH CENTER
|
| Motors, magnetic bearings, and other electromagnetic actuators that can operate at 1000 degrees F (540 degrees C) hold great promise for providing increased efficiency in machinery for many applications ranging from pebble-bed nuclear reactors and chemical processing to aircraft and unmanned aerial combat vehicle (UCAV) propulsion systems. This report discusses in detail the design and fabrication of a high-temperature, heteropolar, radial magnetic bearing that was operated at 1000 degrees F ... |
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| Modified Involute Helical Gears: Computerized Design, Simulation of Meshing and Stress Analysis |
JUN 2003 |
66 pages |
| Authors:
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH GLENN RESEARCH CENTER
|
| The computerized design, methods for generation, simulation of meshing, and enhanced stress analysis of modified involute helical gears is presented. The approaches proposed for modification of conventional involute helical gears are based on conjugation of double-crowned pinion with a conventional helical involute gear. Double-crowning of the pinion means deviation of cross-profile from an involute one and deviation in longitudinal direction from a helicoid surface. Using the method developed, the pinion-gear ... |
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| Spiral Bevel Pinion Crack Detection in a Helicopter Gearbox |
JUN 2003 |
16 pages |
| Authors:
Harry J. Decker; David G. Lewicki; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH GLENN RESEARCH CENTER
|
| The vibration resulting from a cracked spiral bevel pinion was recorded and analyzed using existing Health and Usage Monitoring System (HUMS) techniques. A tooth on the input pinion to a Bell OH-58 main rotor gearbox was notched and run for an extended period at severe over-torque condition to facilitate a tooth fracture. Thirteen vibration-based diagnostic metrics were calculated throughout the run. After 101.41 hours of run time, some of the ... |
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| A Statistical Analysis of Laser Ablated Ba(0.50)Sr(0.50)TiO3/LaAlO3 Films for Microwave Applications |
03 APR 2003 |
|
| Authors:
R. R. Romanofsky; N. C. Varaljay; S. A. Alterovitz; F. A. Miranda; C. M. Mueller; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH GLENN RESEARCH CENTER
|
 | The NASA Glenn Research Center is constructing a 616 element scanning phased array antenna using thin film Ba(x)Sr(1-x)TiO3 based phase shifters. A critical milestone is the production of 616 identical phase shifters at 19 GHz with ^^4 dB insertion loss and at least 337.5 deg phase shift with 3 percent bandwidth. It is well known that there is a direct relationship between dielectric tuning and loss due to the Kramers-Kronig ... |
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| Efficiency of High-Speed Helical Gear Trains |
APR 2003 |
16 pages |
| Authors:
Robert R. Handschuh; Charles J. Kilmain; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH GLENN RESEARCH CENTER
|
| An experimental and analytical comparison of the efficiency of high- speed helical gear trains is presented. An analysis of the gearing losses was conducted and was used as a comparison to the measured losses. Test data from a helical gear train at varying speeds and loads (to 3730 KW (5000 hp) and 15000 RPM) was collected. A comparison of the results indicated that drive system rotational speed had the most ... |
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| Effects on Diagnostic Parameters After Removing Additional Synchronous Gear Meshes |
APR 2003 |
14 pages |
| Authors:
Harry J. Decker; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH GLENN RESEARCH CENTER
|
| Gear cracks are typically difficult to diagnose with sufficient time before catastrophic damage occurs. Significant damage must be present before algorithms appear to be able to detect the damage. Frequently there are multiple gear meshes on a single shaft. Since they are all synchronous with the shaft frequency, the commonly used synchronous averaging technique is ineffective in removing other gear mesh effects. Carefully applying a filter to these extraneous gear ... |
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| Experimental High Temperature Characterization of a Magnetic Bearing for Turbomachinery |
MAR 2003 |
17 pages |
| Authors:
Gerald Montague; Mark Jansen; Andrew Provenza; Alan Palazzolo; Ralph Jansen; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH GLENN RESEARCH CENTER
|
| Open loop, experimental force and power measurements of a radial, redundant-axis, magnetic bearing at temperatures to 1000 degrees F (538 degrees C) and rotor speeds to 15,000 RPM along with theoretical temperature and force models are presented in this paper. The experimentally measured force produced by a single C-core using 22A was 600 pounds (2.67 kN) at room temperature and 380 pounds (1.69 kN) at 1000 degrees F (538 degrees ... |
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| Kalman Filtering With Inequality Constraints for Turbofan Engine Health Estimation |
FEB 2003 |
36 pages |
| Authors:
Dan Simon; Donald L. Simon; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH GLENN RESEARCH CENTER
|
| Kalman filters are often used to estimate the state variables of a dynamic system. However, in the application of Kalman filters some known signal information is often either ignored or dealt with heuristically. For instance, state variable constraints (which may be based on physical considerations) are often neglected because they do not fit easily into the structure of the Kalman filter. This paper develops two analytic methods of incorporating state ... |
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| Coupled Multi-Disciplinary Optimization for Structural Reliability and Affordability |
FEB 2003 |
10 pages |
| Authors:
Galib H. Abumeri; Christos C. Chamis; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH GLENN RESEARCH CENTER
|
| A computational simulation method is presented for Non-Deterministic Multidisciplinary Optimization of engine composite materials and structures. A hypothetical engine duct made with ceramic matrix composites (CMC) is evaluated probabilistically in the presence of combined thermo-mechanical loading. The structure is tailored by quantifying the uncertainties in all relevant design variables such as fabrication, material, and loading parameters. The probabilistic sensitivities are used to select critical design variables for optimization. In this ... |
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| Aerodynamic Design Study of Advanced Multistage Axial Compressor |
DEC 2002 |
39 pages |
| Authors:
Louis M. Larosiliere; Jerry R. Wood; Michael D. Hathaway; Adam J. Medd; Thong Q. Dang; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH GLENN RESEARCH CENTER
|
| As a direct response to the need for further performance gains from current multistage axial compressors, an investigation of advanced aerodynamic design concepts that will lead to compact, high-efficiency, and wide-operability configurations is being pursued. Part I of this report describes the projected level of technical advancement relative to the state of the art and quantifies it in terms of basic aerodynamic technology elements of current design systems. A rational ... |
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| Room Temperature Characterization of a Magnetic Bearing for Turbomachinery |
OCT 2002 |
14 pages |
| Authors:
Gerald Montague; Mark Jansen; Andrew Provenza; Ralph Jansen; Ben Ebihara; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH GLENN RESEARCH CENTER
|
| Open loop, experimental force and power measurements of a three-axis, radial, heteropolar magnetic bearing at room temperature for rotor speeds up to 20,000 RPM are presented in this paper. The bearing, NASA Glenn Research Center's and Texas A&M's third generation high temperature magnetic bearing, was designed to operate in a 1000 deg. F (540 deg. C) environment and was primarily optimized for maximum load capacity. The experimentally measured force produced ... |
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| Spiral Bevel Gear Damage Detection Using Decision Fusion Analysis |
AUG 2002 |
12 pages |
| Authors:
Paula J. Dempsey; Robert F. Handschuh; Abdollah A. Afjeh; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH GLENN RESEARCH CENTER
|
| A diagnostic tool for detecting damage to spiral bevel gears was developed. Two different monitoring technologies, oil debris analysis and vibration, were integrated using data fusion into a health monitoring system for detecting surface fatigue pitting damage on gears. This integrated system showed improved detection and decision-making capabilities as compared to using individual monitoring technologies. This diagnostic tool was evaluated by collecting vibration and oil debris data from fatigue tests ... |
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| Initial Assessment of the Effects of Nonmetallic Inclusions on Fatigue Life of Powder-Metallurgy-Processed Udimet(R) 720 |
AUG 2002 |
|
| Authors:
T. P. Gabb; J. Telesman; P. T. kantzos; P. J. Bonacuse; R. L. Barrie; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH GLENN RESEARCH CENTER
|
| The fatigue lives of modern powder metallurgy (PM) disk alloys are influenced by variabilities in alloy microstructure and mechanical properties. These properties can vary due to the different steps of materials/component processing and machining. One of these variables, the presence of nonmetallic inclusions. has been shown to significantly degrade low-cycle fatigue (LCF) life. Nonmetallic inclusions are inherent defects in powder alloys that are a by-product of powder-processing techniques. Contamination of ... |
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| The Role of Radial Clearance on the Performance of Foil Air Bearings |
JUL 2002 |
19 pages |
| Authors:
Kevin Radil; Samuel Howard; Brian Dykas; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH GLENN RESEARCH CENTER
|
| Load capacity tests were conducted to determine how radial clearance variations affect the load capacity coefficient of foil air bearings. Two Generation HI foil air bearings with the same design but possessing different initial radial clearances were tested at room temperature against an as-ground PS 304 coated journal operating at 30000 rpm. Increases in radial clearance were accomplished by reducing the journal's outside diameter via an in-place grinding system. From ... |
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| High-Speed, High-Temperature Finger Seal Test Results. AIAA/ASME/SAE/ ASEE Joint Propulsion Conference and Exhibit (38th) Held in Indianapolis, IN on July 7-10, 2002 |
JUL 2002 |
19 pages |
| Authors:
Margaret P. Proctor; Arun Kumar; Irebert R. Delgado; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH GLENN RESEARCH CENTER
|
| Finger seals have significantly lower leakage rates than conventional labyrinth seals used in gas turbine engines and are expected to decrease specific fuel consumption by over 1 percent and to decrease direct operating cost by over 0.5 percent. Their compliant design accommodates shaft growth and motion due to thermal and dynamic loads with minimal wear. The cost to fabricate these finger seals is estimated to be about half the cost ... |
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| Preliminary Investigation of the Thermal Behavior of High-Speed Helical Gear Trains |
MAR 2002 |
18 pages |
| Authors:
Robert F. Handschuh; Charles J. Kilmain; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH GLENN RESEARCH CENTER
|
| A preliminary experimental investigation of the thermal behavior of high-speed helical gears will be presented. A full-scale torque regenerative test stand has been built to test a representative helical gear train as that used in tiltrotor aircraft. Power loss and temperature data from a wide range of operating conditions were measured. Loop power ranged up to 3730 kW (5000 hp). Drive system components representative of flight quality hardware were used ... |
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| Software for Statistical Analysis of Weibull Distributions with Application to Gear Fatigue Data: User Manual with Verification |
JAN 2002 |
36 pages |
| Authors:
Timothy L. Kranz; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH GLENN RESEARCH CENTER
|
| The Weibull distribution has been widely adopted for the statistical description and inference of fatigue data. This document provides user instructions, examples, and verification for software to analyze gear fatigue test data. The software was developed presuming the data are adequately modeled using a two-parameter Weibull distribution. The calculations are based on likelihood methods, and the approach taken is valid for data that include type I censoring. The software was ... |
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| Orientation of Aromatic Ion Exchange Diamines and the Effect on Melt Viscosity and Thermal Stability of PMR-15/ Silicate Nanocomposites |
NOV 2001 |
|
| Authors:
Sandi Campbell; Daniel Scheiman; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH GLENN RESEARCH CENTER
|
| Nanocomposites of PMR-15 polyimide and a diamine modified silicate were prepared by addition of the silicate to the PMR-15 resin. The orientation of the ion exchange diamine within the silicate gallery was determined by x-ray diffraction and found to depend on the clay cation exchange capacity. The oligomer melt viscosity exhibited a dependence on the orientation of the diamine in the silicate interlayer, and in some cases, on the length ... |
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| Experimental Comparison of Face-Milled and Face-Hobbed Spiral Bevel Gears |
OCT 2001 |
13 pages |
| Authors:
Robert F. Handschuh; Michael Nanlawala; John M. Hawkins; Danny Mahan; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH GLENN RESEARCH CENTER
|
| An experimental comparison of face-milled and face-hobbed spiral bevel gears was accomplished. The two differently manufactured spiral bevel gear types were tested in a closed-loop facility at NASA Glenn Research Center. Strain, vibration, and noise testing were completed at various levels of rotational speed and load. Tests were conducted from static (slow-roll) to 12600 rpm and up to 269 N.m (2380 in..lb) pinion speed and load conditions. The tests indicated ... |
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| Gear Crack Propagation Path Studies - Guidelines for Ultra-Safe Design |
JUL 2001 |
15 pages |
| Authors:
David G. Lewicki; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH GLENN RESEARCH CENTER
|
| Design guidelines have been established to prevent catastrophic rim fracture failure modes when considering gear tooth bending fatigue. Analysis was performed using the finite element method with principles of linear elastic fracture mechanics. Crack propagation paths were predicted for a variety of gear tooth and rim configurations. The effects of rim and web thicknesses, initial crack locations, and gear tooth geometry factors such as diametral pitch, number of teeth, pitch ... |
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| The Effect of Journal Roughness and Foil Coatings on the Performance of Heavily Loaded Foil Air Bearings |
JUN 2001 |
27 pages |
| Authors:
Kevin C. Radil; Christopher DellaCorte; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH GLENN RESEARCH CENTER
|
| Foil air bearing load capacity tests were conducted to investigate if a solid lubricant coating applied to the surface of the bearing's top foil can function as a break-in coating. Two foil coating materials, a conventional soft polymer film (polyimide) and a hard ceramic (alumina), were independently evaluated against as-ground and worn (run-in) journals coated with NASA PS304, a high-temperature solid lubricant composite coating. The foil coatings were evaluated at ... |
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| Minimizing Load Effects on NA4 Gear Vibration Diagnostic Parameter |
05 APR 2001 |
12 pages |
| Authors:
Paula J. Dempsey; James J. Zakrajsek; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH GLENN RESEARCH CENTER
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| NA4 is a vibration diagnostic parameter, developed by researchers at NASA Glenn Research Center, for health monitoring of gears in helicopter transmissions. NA4 reacts to the onset of gear pitting damage and continues to react to the damage as it spreads. This research also indicates NA4 reacts similarly to load variations. The sensitivity of NA4 to load changes will substantially affect its performance on a helicopter gearbox that experiences continuously ... |
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| Testing of Face-Milled Spiral Bevel Gears at High-Speed and Load |
MAR 2001 |
12 pages |
| Authors:
Robert F. Handschuh; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH GLENN RESEARCH CENTER
|
| Spiral bevel gears are an important drive system components of rotorcraft (helicopters) currently in use. In this application the spiral bevel gears are required to transmit very high torque at high rotational speed. Available experimental data on the operational characteristics for thermal and structural behavior is relatively small in comparison to that found for parallel axis gears. An ongoing test program has been in place at NASA Glenn Research Center ... |
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| Icing Cloud Calibration of the NASA Glenn Icing Research Tunnel |
MAR 2001 |
28 pages |
| Authors:
Robert F. Ide; John R. Oldenburg; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH GLENN RESEARCH CENTER
|
| The icing research tunnel at the NASA Glenn Research Center underwent a major rehabilitation in 1999, necessitating recalibration of the icing clouds. This report describes the methods used in the recalibration, including the procedure used to establish a uniform icing cloud and the use of a standard icing blade technique for measurement of liquid water content. The instruments and methods used to perform the droplet size calibration are also described. ... |
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| Design, Generation and Tooth Contact Analysis (TCA) of Asymmetric Face Gear Drive With Modified Geometry |
JAN 2001 |
35 pages |
| Authors:
Faydor L. Litvin; Alfonso Fuentes; J. M. Hawkins; Robert F. Handschuh; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH GLENN RESEARCH CENTER
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| A new type of face gear drive for application in transmissions, particularly in helicopters, has been developed. The new geometty differs from the existing geometry by application of asymmetric profiles and double-crowned pinion of the face gear mesh. The paper describes the computerized design, simulation of meshing and contact, and stress analysis by finite element method. Special purpose computer codes have been developed to conduct the analysis. The analysis of ... |
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| Effectiveness of Micro-Blowing Technique in Adverse Pressure Gradients |
JAN 2001 |
13 pages |
| Authors:
Gerard E. Welch; Louis M. Larosiliere; Danny P. Hwang; Jerry R. Wood; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH GLENN RESEARCH CENTER
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| The impact of the micro-blowing technique (MBT) on the skin friction and total drag of a strut in a turbulent, strong adverse-pressure-gradient flow is assessed experimentally over a range of subsonic Mach numbers (0.3 |
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| Flame Spread Along Free Edges of Thermally Thin Samples in Microgravity |
04 AUG 2000 |
8 pages |
| Authors:
W. E. Mell; S. L. Olson; T. Kashiwagi; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH GLENN RESEARCH CENTER
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| The effects of imposed flow velocity on flame spread along open edges of a thermally thin cellulosic sample in microgravity were studied experimentally and theoretically. In this study, the sample was ignited locally at the middle of the 4 cm wide sample, and subsequent flame spread reached both open edges of the sample along the direction of the flow. The following flame behaviors were observed in the experiments and predicted ... |
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