| Performance Limiting Flow Processes in High-State Loading High-Mach Number Compressors |
13 MAR 2008 |
67 pages |
| Authors:
Choon S. Tan; MASSACHUSETTS INST OF TECH CAMBRIDGE GAS TURBINE LAB
|
 | In high-stage loading high-Mach number (HLM) compressors, counter-rotating pairs of discrete vortices are shed at the trailing edge of the upstream blade row at a frequency corresponding to the downstream rotor blade passing frequency. This is a consequence of an alternating change in blade loading caused by the passage of shocks or compression waves emanating from the downstream rotor. While this effect is present at any Mach number the combination ... |
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| Turbulence and Complex Flow Phenomena in Multi-Stage Axial Turbomachines |
10 MAY 2007 |
35 pages |
| Authors:
Joseph Katz; Charles Meneveau; JOHNS HOPKINS UNIV BALTIMORE MD DEPT OF MECHANICAL ENGINEERING
|
| The objective of this project is to measure the flow within axial turbomachines and use the data to address turbulence modeling issues. Measurements are performed in two-stage transparent machines located in an optically index matched facility, which allows unobstructed 2-D and Stereo PIV measurements. Data provide insight on blade-wake, wake- boundary layer and wake-wake interactions. This report examines and elucidates several phenomena: i. Variations in turbulence within a wake generated ... |
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| Effect of Pressure and Temperature On Oil Mist Sprays Used for Blade Excitation in High Cycle Fatigue Testing |
JUN 2006 |
151 pages |
| Authors:
Andrew P. Thompson; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| The flow patterns of two oil mist nozzles used in rotor blade excitation experiments were characterized using a Laser Doppler Velocimeter (LDV). Both nozzles were operated in a vacuum test chamber and velocity measurements were taken at three axial distances from the nozzle exit, at three or four different pressures, at three different temperatures. The 4 gallon per hour mini-mist nozzle produced a referenced velocity consistent with a hollow cone ... |
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| A New Non-Incremental Finite Element Solution Procedure for Rotor Dynamics |
30 NOV 2005 |
9 pages |
| Authors:
Ahmed A. Shabana; ILLINOIS UNIV AT CHICAGO
|
| The goal of this research project was to explore the use of a new finite element procedure in the analysis of rotor blades. The use of the large deformation finite element absolute nodal coordinate formulation in the analysis of rotating blades was examined. several important problems were identified and solved. and new challenges are encountered and discussed in this report. The developments made in this research project include introducing new ... |
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| Laser Velocimetric Flow Mapping and Characterization of Oil Mist Nozzles Used for Blade Excitation in High Cycle Fatigue Testing |
SEP 2005 |
79 pages |
| Authors:
Christopher M. Vonderheide; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| The flow patterns of two oil mist nozzles used in rotor blade excitation experiments were flow mapped using a traversing Laser Doppler Velocimeter (LDV) system to determine the velocity and the overall characteristics were recorded photographically. The nozzles were operated in a vacuum test chamber and measurements were obtained at three different spray pressures, at three different axial distances from the nozzle exit. For a 4 gallon per hour (gph) ... |
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| Turbine Engine Research Center (TERC) Data System Enhancement and Test Article Evaluation. Delivery Order 0002: TERC Aeromechanical Characterization |
JUN 2005 |
375 pages |
| Authors:
Pamela S. Teets; Walter O'brien; Vince Capece; Choon Tan; BATTELLE DAYTON OPERATIONS OH
|
| Battelle has supported the Air Force Compressor Research Facility from May 13, 2003 through June 30, 2005 under this Delivery Order. Under this Delivery Order, aeromechanical characterization research was performed in conjunction with testing performed in the Turbine Engine Research Center (TERC). This research involved data analysis to identify new behavior, verify codes and model simulating aeromechanical behavior, and perform aeromechanical test and evaluation of hardware undergoing testing in the ... |
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| Helicopter with Torque-Correcting Thruster Device |
09 MAR 2005 |
30 pages |
| Authors:
James R. Quartarone; DEPARTMENT OF THE NAVY WASHINGTON DC
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| This patent application discloses a helicopter having a torque-correcting thruster device. The helicopter has an aerodynamic body which has opposite side portions, a top portion and a bottom portion. The aerodynamic body has a cockpit and a pilot seat in the cockpit. The helicopter includes landing gear attached to the bottom portion of the aerodynamic body. The helicopter includes a rotor that is supported by the aerodynamic body and a ... |
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| A Complete Rotor Wake Model in State Space |
01 SEP 2004 |
25 pages |
| Authors:
David A. Peters; WASHINGTON UNIV ST LOUIS MO
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| This research deals with the development of a finite-state inflow theory that will be able to predict all three components of flow both on and off of the rotor disk. The theory will be of a velocity potential expanded in hierarchical degrees of freedom. |
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| Experiment-Based Development and Validation of Mistuning Models for Bladed Disks |
27 AUG 2004 |
18 pages |
| Authors:
christopher pierre; MICHIGAN UNIV ANN ARBOR DEPT OF MECHANICAL ENGINEERING
|
| The primary objective of this project was to perform experimental work to further the understanding of the fundamental physics of mistuned bladed disks. The experiments that were carried out during the course of this project have served to corroborate analytical and numerical findings, to validate the computational methods that have been developed to date, and to guide the development of improved models and methods that incorporate the relevant physics. In ... |
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| A Study of a Skirtless Hovercraft Design |
MAY 2004 |
70 pages |
| Authors:
Edward A. Kelleher; AIR FORCE INST OF TECH WRIGHT-PATTERSONAFB OH DEPT OF AERONAUTICS AND ASTRONAUTICS
|
| Initial study into three possible skirtless hovercraft designs. The designs utilize Coanda nozzles and a Coanda wing surface to generate lift and create a pressure cushion below the craft. The pressure cushion is to be maintained by an air curtain created by flow spill from the Coanda wing surface. Three proposed skirtless hovercraft designs were analyzed via computational fluid dynamics to ascertain their lift generation capabilities. The three designs were ... |
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| Analytical Calculation of Helicopter Main Rotor Blade Flight Loads in Hover and Forward Flight |
APR 2004 |
24 pages |
| Authors:
Ki C. Kim; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| An aeroelastic analysis was conducted to calculate flight loads on the OH-58D Kiowa Warrior main rotor blade at hover and forward flight conditions. Centrifugal force and flap and chord bending moments were calculated with the University of Maryland Advanced Rotorcraft Code (UMARC) comprehensive helicopter aeroelastic analysis code. The calculated loads were correlated with available flight data for the Bell model 406LM helicopter (model 406T rotor blade) to validate the analytical ... |
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| The Near-Wall Behavior of Unsteady Vortical Flow Around the Tip of an Axial Pump Rotor Blade |
15 DEC 2003 |
36 pages |
| Authors:
Roger L. Simpson; VIRGINIA POLYTECHNIC INST AND STATE UNIV BLACKSBURG DEPT OF AEROSPACE AND OCEAN ENGINEERING
|
| Experimental study of three-dimensional turbulent tip gap flows in the linear cascade wind tunnel for two different tip gap clearances (t/c=1 .65% and 3.3%). Three experimental techniques are used to measure the tip gap velocity field and static pressure field on the end-wall: a three- orthogonal- velocity- component fiber-optic laser Doppler anemometer (3D-LDA) system, surface oil flow visualization, and a scani-valve pressure measurement system. The end-wall skin friction velocity is ... |
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| Aerodynamic Characteristics of SC1095 and SC1094 R8 Airfoils |
DEC 2003 |
50 pages |
| Authors:
William G. Bousman; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION MOFFETT FIELD CA AMES RESEARCH CENTER
|
| Two airfoils are used on the main rotor blade of the UH-60A helicopter, the SC 1095 and the SC1094 RS. Measurements of the section lift, drag, and pitching moment have been obtained in ten wind tunnel tests for the SC1095 airfoil, and in five of these tests, measurements have also been obtained for the SC1094 R8. The ten wind tunnel tests are characterized and described in the present study. A ... |
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| A Three-Dimensional Flutter Theory For Rotor Blades With Trailing-Edge Flaps |
JUN 2003 |
237 pages |
| Authors:
Mark A. Couch; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| This dissertation develops the equations of motion for the structural and aerodynamic forces and moments of a rotor blade with a trailing-edge flap using eight degrees of freedom. Lagrange's equation is applied using normal modes to find the flutter frequency and speed similar to the classic fixed-wing method developed by Smilg and Wasserman. However, rotary-wing concerns are addressed including different freestream velocities along the blade (variation of reduced frequency along ... |
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| A Water Tunnel Investigation of a Small Scale Rotor Operating in the Vortex Ring State |
JUN 2003 |
77 pages |
| Authors:
Charles B. Rumsey Jr; NAVAL POSTGRADUATE SCHOOL MONTEREY CA DEPT OF PHYSICS
|
| Motivation to expand the understanding of a helicopter rotor descending into the vortex ring state (VRS) stems from the aircraft mishaps that have plagued the helicopter community. The V-22 has become the most recent victim of encounters with VRS. The onset of VRS is associated with the collapse of the helical vortex wake in the plane of the rotor. The resulting wake disturbances develop an irregular and aperiodic flow. Rotor ... |
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| Dynamic Stall Measurements and Computations for a VR-12 Airfoil with a Variable Droop Leading Edge |
MAY 2003 |
19 pages |
| Authors:
P. B. Martin; K. W. McAlister; M. S. Chandrasekhara; W. Geissler; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION MOFFETT FIELD CA ROTORCRAFT DIVISION
|
| High density-altitude operations of helicopters with advanced performance and maneuver capabilities have lead to fundamental research on active high-lift system concepts for rotor blades. The requirement for this type of system was to improve the sectional lift-to-drag ratio by alleviating dynamic stall on the retreating blade while simultaneously reducing the transonic drag rise of the advancing blade. Both measured and computational results showed that a Variable Droop Leading Edge (VDLE) ... |
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| An Alternate Air System Concept for Application in a High Pressure Turbine |
MAR 2003 |
11 pages |
| Authors:
Dieter Peitsch; Winfried-Hagen Friedl; BMW ROLLS-ROYCE GMBH DAHLEWITZ (GERMANY)
|
| In 1995, the German government initiated an aerospace research program in order to support the capabilities of german companies in the more and more challenging environment of aerospace business. Engine 3E is the research part of this overall program concentrating on jet engines. It's aim was to develop technologies to reduce the impact of turbojet engines onto the environment, where 3E stands for Efficiency, Economy and Environment. In this research ... |
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| Measurements of the Early Development of Trailing Vorticity from a Rotor |
JUL 2002 |
67 pages |
| Authors:
Kenneth W. McAlister; James T. Heineck; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION MOFFETT FIELD CA AMES RESEARCHCENTER
|
| The wake behind a two-bladed model rotor in light climb was measured using particle image velocimetry, with particular emphasis on the development of the trailing vortex during the first revolution of the rotor. The distribution of vorticity was distinguished from the slightly elliptical swirl pattern. Peculiar dynamics within the "void" region may explain why the peak vorticity appeared to shift away from the center as the vortex aged, suggesting the ... |
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| AHFID Propulsor Performance Prediction |
JAN 2002 |
30 pages |
| Authors:
Thad J. Michael; Stuart D. Jessup; Otto Scherer; NAVAL SURFACE WARFARE CENTER CARDEROCK DIV BETHESDA MD
|
| The thrust and torque of the propulsor tor the Advanced Hull Form Inshore Demonstrator were predicted using a vortex lattice propeller code coupled with an Euler solver. The propulsor is a post-swirl ducted unit with the rotor band recessed into the duct inner surface. To predict the additional torque due to the recessed band, empirical methods were used. The demonstration- scale propulsor is predicted to absorb 2360 hp (1760 kW) ... |
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| Advanced Rotor Aerodynamics Concepts with Application to Large Rotorcraft |
JAN 2002 |
15 pages |
| Authors:
Matthew W. Floros; Wayne Johnson; Michael P. Scully; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION MOFFETT FIELD CA AMES RESEARCH CENTER
|
| A study was conducted using the comprehensive analysis CAMRAD II to explore performance enhancements to large rotorcraft. The aircraft considered were a 125 foot diameter six-bladed rotor helicopter and an 85 foot diameter four-bladed rotor tilt rotor. The objectives were to reduce power required and increase maximum lift. The effects of improved airfoils and active controls were investigated. Airfoils with higher maximum lift and with reduced drag were investigated. Results ... |
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| Comparison of Full-Scale XV-15 Blade-Vortex Interaction Noise Calculations with Wind Tunnel Data |
JAN 2002 |
11 pages |
| Authors:
Cahit Kitaplioglu; Wayne Johnson; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION MOFFETT FIELD CA ROTORCRAFT DIVISION
|
| Results from the TRAC acoustic prediction system were correlated with data from a test of an isolated full-scale XV-15 rotor in the NASA Ames 80- by 120-Foot Wind Tunnel. The airloads calculation provided by the original CAMRAD.Mod1 code in the standard TRAC system was exercised with several high resolution options, including the FPXBVI CFD code. In addition, the more recent CAMRAD II code was run in place of the original ... |
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| Unsteady Shock Wave - Boundary Layer Interactions FY 2000 AFOSR entrepreneurial Research Task |
DEC 2001 |
6 pages |
| Authors:
Gregory Addington; William W. Copenhaver; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH AIR VEHICLES DIRECTORATE
|
| The objective of the research performed was to investigate shock - boundary layer interactions at transonic conditions in the presence of unsteady vortex flows originating upstream of the shock location. These conditions are germane to both external and internal flows: principally, flows over a geometry representative of a modern fighter wing at transonic maneuvering conditions and within transonic compressor states, respectively. Despite intentions to the contrary, these conditions were studied ... |
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| Large Eddy Simulations of Complex Turbulent Flows Using Immersed Boundary Method |
AUG 2001 |
|
| Authors:
Mayank Tyagi; Sumanta Acharya; LOUISIANA STATE UNIV BATON ROUGE DEPT OF MECHANICAL ENGINEERING
|
 | Large eddy simulations (LES) are performed for two representative complex geometry problems of particular interest to turbomachinery flows, First problem studied is the flow field inside a trapped-vortex combustor. Second problem is the unsteady interaction of rotor blade with stator blade wake field. The representation of complex geometry is done using immersed boundary method (IBM). Two different implementations are presented for the body force terms. |
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| Experimental Investigation in Vibration Control and Damage Detection of Smart Composites |
12 JUL 2001 |
5 pages |
| Authors:
Aditi Chattopadhyay; ARIZONA STATE UNIV TEMPE DEPT OF MECHANICAL AND AEROSPACE ENGINEERING
|
| The Laser Doppler Vibrometer (LDV) optical instrument purchased under the DURIP grant is used for accurately measuring velocity (and displacement) of vibrating surfaces completely without contact. It is a complete, self-contained area vibration measurement and analysis system. The LDV automatically collects complete vibration data from up to thousands of individual points on a user- defined area. An important feature in scanning vibrometers is the ability to validate and improve the ... |
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| The Origin and Structure of Trailing Vortices in Aerodynamics |
06 JUL 2001 |
252 pages |
| Authors:
A. T. Conlisk; N. M. Komarath; OHIO STATE UNIV RESEARCH FOUNDATION COLUMBUS
|
| The helicopter rotor wake is among the most complex flow-fields in aerodynamics. Despite the fact that a large amount of computational and experimental work on the rotor wake has been published, little of a quantitative nature is known about the origin of the main component of the rotor wake, the tip-vortex, as a function of the rotor speed, rotor blade geometry, and angle of attack. The primary objective of this ... |
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| Experiment-Based Development of Phenomenological Mistuning Models for Bladed Disks |
JUN 2001 |
11 pages |
| Authors:
Christophe Pierre; Steven L. Ceccio; Matthew P. Castanier; John Judge; MICHIGAN UNIV ANN ARBOR DEPT OF MECHANICAL ENGINEERING
|
| The major objectives of this research were: (1) to demonstrate and quantify the high sensitivity of bladed disks to mistuning, and in particular, the occurrence of vibration localization phenomena and associated forced response amplitude increases, (2) to achieve an understanding of the various sources and physical mechanisms of mistuning for a typical bladed disk and to develop the corresponding models, and (3) to utilize the mistuning models developed to identify ... |
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| Calculation of the Aerodynamic Behavior of the Tilt Rotor Aeroacoustic Model (TRAM) in the DNW |
MAY 2001 |
38 pages |
| Authors:
Wayne Johnson; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION MOFFETT FIELD CA AMES RESEARCH CENTER
|
| Comparisons of measured and calculated aerodynamic behavior of a tiltrotor model are presented. The test of the Tilt Rotor Aeroacoustic Model (TRAM) with a single, 1/4-scale V- 22 rotor in the German-Dutch Wind Tunnel (DNW) provides an extensive set of aeroacoustic, performance, and structural loads data. The calculations were performed using the rotorcraft comprehensive analysis CAMRAD II. Presented are comparisons of measured and calculated performance and airloads for helicopter mode ... |
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| Fan Rotor with Construction and Safety Performance Optimization |
13 MAR 2001 |
27 pages |
| Authors:
John J. Larzelere; Dale W. Sisson Jr.; Craig S. LaMoy; Charles K. Atwell; Thomas W. VanDoren; DEPARTMENT OF THE NAVY WASHINGTON DC
|
| A one-piece fan rotor optimized for construction and safety performance criteria is provided. The rotor has a hub with a radial cross-section defined by an I-beam. A plurality of unequally-spaced rotor blades are disposed circumferentially around and extend radially outward from the hub. Each rotor blade has a root portion coupled to the hub with the root portion defined by a concave fillet circumventing the rotor blade. For rotational balance, ... |
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| Computational Investigation of Aeromechanical HCF Effects in a Compressor Rotor |
MAR 2001 |
107 pages |
| Authors:
Andrew L. White; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
|
| High-Cycle Fatigue is a major problem facing the gas turbine industry today. It has been investigated by many researchers, using many different methods. Due to its highly complex nature, designers still do not have adequate tools to accurately predict the onset of high-cycle fatigue. A three-dimensional Navier-Stokes program was used to perform a study of the unsteady aerodynamics on a compressor rotor. The effect of aerodynamic detuning on the forced ... |
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| Nonlinear Modal Analysis and Component Mode Synthesis of Large-Scale Structural Systems |
20 FEB 2001 |
7 pages |
| Authors:
Christohe Pierre; Steven W. Shaw; MICHIGAN UNIV ANN ARBOR OFFICE OF RESEARCH ADMINISTRATION
|
| The objective of this research was the development and implementation of computational modal analysis methodologies for large scale, complex, nonlinear structures. These methods are based on nonlinear modes of vibration defined and constructed in terms of invariant manifolds. The motivation for the research stems from the fact that the dynamics of nonlinear structures are typically decomposed in terms of the linearized system S modes, often yielding poor modal convergence and ... |
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| Modeling and Analysis of Composites Using Smart Materials and Optimization Techniques |
06 FEB 2001 |
8 pages |
| Authors:
A. Chattopadhyay; ARIZONA STATE UNIV TEMPE
|
| The vibratory load reduction at rotor hub using self-sensing piezoelectric material and closed loop control is investigated, A composite box beam theory is developed to model the primary load carrying structure in the rotor blade. In this theory, a higher order displacement field is used to model the individual walls of the composite box beam with surface bonded piezoelectric actuators. Based on these techniques, an integrated rotor vibratory load analysis ... |
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| Preliminary Study of a Model Rotor in Descent |
NOV 2000 |
41 pages |
| Authors:
K. W. McAlister; C. Tung; D. L. Sharpe; S. Huang; E. M. Hendley; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION MOFFETT FIELD CA AMES RESEARCHCENTER
|
| Within a program designed to develop experimental techniques for measuring the trajectory and structure of vortices trailing from the tips of rotor blades, the present preliminary study focuses on a method for quantifying the trajectory of the trailing vortex during descent flight conditions. This study also presents rotor loads and blade surface pressures for a range of tip- path plane angles and Mach numbers. Blade pressures near the leading edge ... |
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| Steady and Unsteady Heat Transfer in a Film-Cooled Transonic Turbine Cascade |
JUL 2000 |
266 pages |
| Authors:
Wing Ng; Tom Diller; Oliver Popp; VIRGINIA POLYTECHNIC INST AND STATE UNIV BLACKSBURG DEPT OF MECHANICAL ENGINEERING
|
| The unsteady interaction of shock waves emerging from the trailing edge of modern turbine nozzle guide vanes and impinging on downstream rotor blades is modeled in a linear cascade. The Reynolds number based on blade chord and exit conditions (5 x 10(exp 6) and the exit Mach number (1.2) are representative of modern engine operating conditions. The relative motion of shocks and blades is ... |
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| A Cost Analysis of the Decision to Cannibalize Major Components of the Navy's H-60 Helicopters at the Operational Level |
JUN 2000 |
88 pages |
| Authors:
Danny E. Kowalski; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| Cannibalization is a technique, sanctioned by the Navy, for maintenance managers to optimize aircraft availability by circumventing a slow or inadequate logistics support system Maintenance managers often make a decision to cannibalize without considering the total cost of their decision This thesis examines the costs incurred by an operational H-6O helicopter squadron to cannibalize major components and addresses the impact of cannibalization on the ... |
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| Steady and Periodic Pressure Measurements on a Generic Helicopter Fuselage Model in the Presence of a Rotor |
JUN 2000 |
188 pages |
| Authors:
Raymond E. Mineck; Susan A. Gorton; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION HAMPTON VA LANGLEY RESEARCH CENTER
|
| Helicopter airframes are subjected to periodic air-loads due principally to the rotating main rotor blades. The periodic air loads impact the noise and vibration within the passenger cabin as well as the fatigue life of the airframe. Computational techniques have been and are being developed to predict these periodic airframe air loads. Periodic pressure measurements are needed on simple configurations for validation of the computational techniques. Few experimental data sets ... |
|
| Proceedings of CEAS Forum on Aeroacoustics of Rotors and Propellers, 9- 11 June 1999, Rome Italy |
11 JUN 1999 |
204 pages |
| Authors:
UNIVERSITA DEGLI STUDI LA SAPIENZA ROME(ITALY)
|
| The CEAS Forum on Aeroacoustics of Rotors and Propellers is intended to give a comprehensive survey of the state of the art in the field and to provide an opportunity to scientists and engineers from industry, research establishments and universities to present new results based on their recent studies, to exchange opinions and experiences, and to discuss directions of future research. The program's technical content ... |
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| Experimental and Computational Investigation of Cold-Flow Through the Turbine of the Space-Shuttle Main Engine High-Pressure Fuel Turbopump |
SEP 1998 |
134 pages |
| Authors:
Joseph R. McKee; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| Computational predictions and experimental measurements were made on the Naval Postgraduate School's cold-flow turbine test rig. The test turbine was the Space-Shuttle Main Engine, High-Pressure Fuel Turbopump, Alternate Development Model, designed and manufactured by Pratt & Whitney. The flow-field around the first-stage rotor end-wall region was measured using a laser-Doppler velocimetry (LDV) system. Measurements were taken at two axial locations over the rotor blade tip ... |
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| Void Nucleation and Growth in Nonlinear Solids |
30 AUG 1998 |
15 pages |
| Authors:
Cornelius O. Horgan; VIRGINIA UNIV CHARLOTTESVILLE SCHOOL OF ENGINEERING AND APPLIED SCIENCE
|
| Thin-walled structures of interest to the U. S. Air Force, such as aircraft fuselages, rocket casings, helicopter blades, and containment vessels, are often constructed of layers of anisotropic, filament or fiber-reinforced materials which must be designed to remain elastic. Our research has been concerned with load diffusion in such structures. An understanding of the fundamental mechanisms of load diffusion in composite subcomponents is essential in ... |
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| Analyzing Discrete Event Simulation Models of Complex Manufacturing Systems: A Computational Complexity Approach |
30 JAN 98 |
23 pages |
| Authors:
Sheldon H. Jacobson; VIRGINIA POLYTECHNIC INST AND STATE UNIV BLACKSBURG DEPT OF INDUSTRIAL AND SYSTEMS ENGINEERING
|
| Discrete manufacturing process design optimization is a challenging problem for the Air Force, due to the large number of manufacturing process design sequences that exist for a given part. This has forced researchers to develop heuristic strategies to address such design problems. This report summarizes the work done in developing a new general heuristic search strategy for discrete manufacturing process design optimization, called generalized hill climbing algorithms. Generalized hill climbing ... |
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| Marine Propulsion System for Underwater Vehicles. |
30 DEC 1997 |
|
| Authors:
Chahee P. Cho; William P. Krol Jr; DEPARTMENT OF THE NAVY WASHINGTON DC
|
| A marine propulsion system for underwater vehicles includes motor inner stator assemblies disposed in bull portions of the vehicle, fixed blades extending outwardly from an after one of the hull portions a shroud fixed to outer ends of the fixed blades and encircling the hull portions, and a motor outer stator assembly disposed in the shroud. A rotor hub is disposed in an annular recess formed by the hull portions, ... |
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| Testing and Analysis of a Transonic Axial Compressor |
SEP 1997 |
119 pages |
| Authors:
Bart L. Grossman; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| A test program to evaluate a new transonic axial compressor stage was conducted. The stage was designed (by Nelson Sanger of NASA Lewis) relying heavily on CFD techniques while minimizing conventional empirical design methods. The stage was installed in the NPS Transonic Compressor Test Rig and instrumented with fixed temperature and pressure probes. A new PC-based data acquisition system was commissioned and programmed for stage performance ... |
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| Enhancing Clark Atlanta University Participation in Defense Research, Volumes 1 and 2 |
30 JUN 1997 |
213 pages |
| Authors:
Kofi B. Bota; CLARK ATLANTA UNIV GA
|
| The Army-supported research program focused on interdisciplinary research areas in environmental technologies: flow, structures and materials, and software engineering. The program aimed at enhancing CAU's research capabilities, through development of resources and facilities (including equipment and personnel) in areas relevant to the Department of Defense. Several projects were executed to develop expertise and research programs that fall within the mission goals and program objectives of the Department of Defense. ... |
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| Stepped Tip Gap Effects on a Transonic Axial-Flow Compressor Rotor |
JUN 1997 |
321 pages |
| Authors:
Donald W. Thompson; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH
|
| The effects of stepped tip gaps and clearance levels on the performance, flowfield, and stall characteristics of a transonic axial-flow compressor rotor were experimentally and numerically determined. A theory and mechanism for relocation of blockage in the rotor tip region was developed. A two-stage compressor with no inlet guide vanes was tested in the Wright Laboratories Compressor Research Facility located at Wright-Patterson Air Force Base, Ohio. The first-stage rotor was ... |
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| Helicopter Trim Analysis |
JUN 96 |
46 pages |
| Authors:
Joseph Fries; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| This report presents a generic first-principles helicopter trim analysis for use on a personal work station. Working from the helicopter's physical properties, it calculates the main rotor blade's collective, longitudinal cyclic, body pitch, and stabilator pitch angles to maintain a trimmed flight condition over a complete forward-speed range. The computer program automatically sweeps through a forward-speed range, varying the collective, longitudinal cyclic, and stabilator pitch angles to satisfy the trimmed ... |
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| A Marine Propulsion System for Underwater Vehicles. |
01 MAY 1996 |
18 pages |
| Authors:
Chahee P. Cho; William P. Krol; DEPARTMENT OF THE NAVY WASHINGTON DC
|
| A marine propulsion system for underwater vehicles includes motor inner stator assemblies disposed in hull portions of the vehicle, fixed blades extending outwardly from an after one of the hull portions, a shroud fixed to outer ends of the fixed blades and encircling the hull portions, and a motor outer stator assembly disposed in the shroud. A rotor hub is disposed in an annular recess formed by the hull portions, ... |
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| Durability Modeling and Design of a Helicopter Rotor Tie Bar |
SEP 95 |
81 pages |
| Authors:
Gregory P. Sauter; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| The CH.46 Tie Bar is a multiple leaf, stainless steel system that attaches the rotor blade to the rotating hub and carries rotor blade centrifugal force. The Tie Bar twists as the rotor blade feathers and bends slightly as the Pitch Housing bends. Originally designed to last 3,000 hours without any component breakages, the Tie Bar has experienced field failures that have necessitated inspections every 10 flight hours. Traditional fatigue ... |
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| Application of a Modified Dynamic Compression System Model to a Low- Aspect-Ratio Fan: Effects of Inlet Distortion |
AUG 95 |
84 pages |
| Authors:
Kimball A. Shahrokhi; ARNOLD ENGINEERING DEVELOPMENT CENTER ARNOLD AFS TN
|
| The objective of this research was to modify and calibrate a l-D dynamic compression system model, DYNTECC, to more accurately simulate compressor operation with steady, nonuniform inlet flow. The modifications were based upon parallel compressor theory, and modeled both circumferential and radial effects of distorted inlet flow. The modifications included circumferential and radial mass redistribution, dynamic blade response, and radial work redistribution. The circumferential mass redistribution allowed mass transport between ... |
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| Development of a System for Improved Helicopter Blade Tracking |
30 JUN 95 |
79 pages |
| Authors:
Richard L. Bielawa; Kirk Frederickson; RENSSELAER POLYTECHNIC INST TROY NY
|
| This report presents the results of the Phase II experimental verification portion of a research program in support of the development of a quality control system for obtaining improved helicopter rotor blade tracking. The specific objective of the system is the accurate concurrent measurement of both the first and second mass moments (i.e., the static mass moment and the mass moment of inertia). The results of the Phase I study ... |
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| Wavelet Transformations for Helicopter Identification via Acoustic Signatures |
MAY 94 |
25 pages |
| Authors:
Jeffrey L. Solka; Carey E. Priebe; Halford I. Hayes; George W. Rogers; NAVAL SURFACE WARFARE CENTER DAHLGREN DIV VA
|
| The ability to classify helicopters based on their acoustic signature has applications to both detection and tracking. The current approach to this problem uses standard signal-processing techniques to extract features based on the fundamental harmonics of the helicopters' blades. This document examines the role that the wavelet transformation might play in this feature extraction process. It addresses ways to use the wavelet transform both to improve the performance of the ... |
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| Closed Loop Vibrational Control: Theory and Applications |
15 DEC 93 |
95 pages |
| Authors:
Semyon M. Meerkov; Pierre T. Kabamba; Eng-Kee Poh; MICHIGAN UNIV ANN ARBOR DEPT OF ELECTRICAL ENGINEERING AND COMPUTER SCIENCE
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| In this project, a novel control technique, referred to as Closed Loop Vibrational Control, is developed and applied to the problem of fuselage vibrations suppression in helicopter dynamics. This technique is applicable to systems where the control input enters the open loop dynamics as an amplitude of a periodic, zero average function, and this amplitude can be chosen to depend on the systems outputs. An example of such a system ... |
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ROTOR BLADES
