| Effects of Reacting Cross-Stream Flow on Turbine Film Cooling (Postprint) |
Jan 2010 |
11 pages |
| Authors:
Wesly S Anderson; Marc D Polanka; Joseph Zelina; Dave S Evans; Scott D Stouffer; Garth R Justinger; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIRECTORATE
|
 | Film cooling plays a critical role in providing effective thermal protection to components in modern gas turbine engines. A significant effort has been undertaken over the last 40 years to improve the distribution of coolant and to ensure that the airfoil is protected by this coolant from the hot gases in the freestream. This film, under conditions with high fuel air ratios, may actually be detrimental to the underlying metal. ... |
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| Turbomachinery Fluid Mechanics and Control |
Jan 2010 |
46 pages |
| Authors:
Steven L Puterbaugh; David Car; S Todd Bailie; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIRECTORATE
|
| Slot jet flow control concepts were developed and explored for the application to axial compressor stators. The concepts were demonstrated in a high speed wind tunnel to simulate a highly loaded stator passage. The midspan boundary layer flow could be forced to attach most effectively with addition of streamwise vorticity (vortex generators and discrete jets) however the endwalls continue to be poorly behaved until large fractions of the overall flow ... |
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| Electrical and Thermal Performance of 1200 V, 100 A, 200 deg C, 4H-SiC MOSFET-based Power Switch Modules |
Nov 2009 |
6 pages |
| Authors:
James Scofield; Neil Merrett; Jim Richmond; Anant Agarwal; Scott Leslie; Charles Scozzie; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIRECTORATE
|
| In this paper we report the electrical and thermal performance characteristics of 1200 V, 100 A, 200-deg C (Tj), SiC MOSFET power modules configured in a dual-switch topology. Each switch-diode pair was populated by 2 x 56 mm2 SiC MOSFETs and 2 x 32 mm2 SiC JBS diodes providing the 100 A rating at 200-deg C. Static and dynamic characterization, over rated temperature and power ranges, highlights the performance potential ... |
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| Stress Field Evolution in a Ball Bearing Raceway Fatigue Spall (PREPRINT) |
Oct-2009 |
40 pages |
| Authors:
Nagaraj K Arakere; Nathan Branch; Vaughn Svendsen; Nelson H Forster; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIRECTORATE
|
| The governing mechanisms of fatigue spall propagation in ball bearing inner raceways are investigated through the use of elastic-plastic finite element modeling, X-Ray Diffraction, and the visual inspection of fatigue spall cracks. The model simulates multiple ball impacts with a fatigue spall's edge in a 208 size ball bearing operating at 10,000 rpm. Ball impacts are shown to cause severe plastic deformation within the spall edge and induce tensile residual ... |
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| Rolling Contact Fatigue Life and Spall Propagation Characteristics of AISI M50, M50 NiL, and AISI 52100. Part 1. Experimental Results (Preprint) |
Oct-2009 |
49 pages |
| Authors:
Nelson H Forster; Lewis Rosado; Kevin L Thompson; Jason W Cooke; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIRECTORATE
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| This paper is the first part of a three-part series which investigates the rolling contact fatigue (RCF) initiation and spall propagation characteristics of three bearing materials, namely AISI 52100, VIM-V AR AISI M50, and VIM-V AR M50NiL steels. Although there is substantial prior work published on the rolling contact fatigue initiation of these materials, little has been published on their spall propagation characteristics after spall initiation. It is recognized that ... |
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| Rolling Contact Fatigue Life and Spall Propagation Characteristics of AISI M50, M50 NiL, and AISI 52100. Part 2. Stress Modeling (Preprint) |
Oct-2009 |
31 pages |
| Authors:
Nagaraj K Arakere; Nathan Branch; Vaughn Svendsen; Nelson H Forster; George Levesque; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIRECTORATE
|
| This is the second part of three-part series that investigates the rolling contact fatigue initiation and spall propagation characteristics of three bearing materials, namely AISI 52100, VIM-VAR M50, and VIM-VAR M50NiL steels. A systematic investigation of effects of rolling contact fatigue (RCF) on evolution of material properties and micro-structural changes resulting in spall propagation rate has not been conducted. As a first step toward understanding spall propagation, we present stress ... |
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| Rolling Contact Fatigue Life and Spall Propagation Characteristics of AISI M50, M50 NiL, and AISI 52100. Part 3. Metallurgical Examination (Preprint) |
Oct-2009 |
30 pages |
| Authors:
Nelson H Forster; Lewis Rosado; William P Ogden; Hitesh K Trivedi; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIRECTORATE
|
| This is the third part of a three-part series which investigates the rolling contact fatigue initiation and spall propagation characteristics of three bearing materials, namely AISI 52100, VIM-VAR M50, and VIM-VAR M50 NiL steels. While there is substantial prior work published on the rolling contact fatigue initiation of these materials, little is known about their spall propagation characteristics after spall initiation. In Part III, 208 size, 40 mm bore bearings ... |
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| Transition in Gas Turbine Engine Control System Architecture: Modular, Distributed, Embedded |
Aug-2009 |
79 pages |
| Authors:
Al Behbahani; Dennis Culley; Bill Mailander; Dewey Benson; Bruce Wood; Derek Weber; Bill Rhoden; Gary Hunter; Casey Carter; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIRECTORATE
|
| Presentations from the Distributed Engine Control Working Group included: Vision and need for future turbine engine control; Implementation and technology challenges; High temperature electronics; Innovation and entry barriers. |
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| Effect of a Compressive Uniaxial Strain on the Critical Current Density of Grain Boundaries in Superconducting YBa2Cu3O7-delta Films |
09-Jul-2009 |
6 pages |
| Authors:
T J Haugan; P N van der Barnes; D C Laan; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIRECTORATE
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| The mechanism by which grain boundaries impede current flow in high-temperature superconductors has resisted explanation for over two decades. We provide evidence that the strain fields around grain boundary dislocations in YBa2Cu3O7-delta thin films substantially suppress the local critical current density Jc. The removal of strain from the superconducting grain boundary channels by the application of compressive strain causes a remarkable increase in Jc. Contrary to previous understanding, the strain-free ... |
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| The Effect of Variable Gravity on the Cooling Performance of a Partially-Confined FC-72 Spray |
Jul-2009 |
214 pages |
| Authors:
John McQuillen; Travis E Michalak; Kirk L Yerkes; Scott K Thomas; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIRECTORATE
|
| This thesis discusses the effects of a variable-gravity environment on the performance of a subcooled partially-confined spray. An experiment, consisting of a test chamber, the associated flow loops, and instrumentation, was fabricated and flown on the NASA Reduced-Gravity Testing Platform. This modified KC-135 aircraft followed a parabolic flight path to provide various acceleration levels. The spray chamber contained two opposing nozzles spraying onto Thick Film Resistor (TFR) heaters, which were ... |
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| Emergence of Dissipative Structures in Current-Carrying Superconducting Wires (Postprint) |
26-May-2009 |
13 pages |
| Authors:
G A Levin; P N Barnes; J S Bulmer; J P Rodriguez; J A Connors; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIRECTORATE
|
| We discuss the emergence of a spontaneous temperature and critical current spatial modulation in current-carrying high-temperature superconducting wire. The modulation of the critical current along the wire on a scale of 3-10 mm forces a fraction of the transport current to crisscross the resistive interface between the superconducting film and normal metal stabilizer attached to it. This generates additional heat that allows such structure to be self-sustainable. Stability and the ... |
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| Control of BaZrO3 Nanorod Alignment in YBa2Cu3O7-X Thin Films by Microstructural Modulation (POSTPRINT) |
Mar-2009 |
5 pages |
| Authors:
P N Barnes; T J Haugan; F J Baca; J N Reichart; R L Emergo; J Z Wu; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIRECTORATE
|
| The alignment of BaZrO3-nanorods (BZO-NRs) in YBa2Cu3O7-x was studied using vicinal substrates to modulate the microstructure. As the vicinal angle was increased to 10 degrees, the angular splay of BZO-NRs increased. Correspondingly, the vortex pinning along the c-axis increased slightly, a possible consequence of enhanced vortex entanglement. Up to 10 degrees, an increasing density of planar defects was observed, while at 20 degrees an orthogonal reorientation of the BZO-NRs along ... |
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| Visualization of Coupling Current Paths in Striated YBCO-Coated Conductors at Frequencies up to 400 HZ |
01-Oct-2008 |
7 pages |
| Authors:
E Demencik; P Usak; S Takacs; I Vavra; M Polak; G A Levin; P N Barnes; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIRECTORATE
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| The magnetic flux density component perpendicular to the broad tape face was mapped by miniature Hall probes in the vicinity of a striated YBCO-coated tape at frequencies of external magnetic field from 21 to 400 Hz, applied perpendicularly to the tape surface. For reasons of modeling the coupling current behaviour in tapes with a conductive substrate, we amplified the coupling current-amplitude by soldering 25 microns thick copper foil on the ... |
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| Flux Pinning Enhancement in YBa2Cu3O7-x Films with BaSnO3 Nanoparticles |
01-Oct-2008 |
7 pages |
| Authors:
P N Barnes; Chakrapani V Varanasi; J Burke; L Brunke; I Maartense; T J Haugan; E A Stinzianni; K A Dunn; P Haldar; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIRECTORATE
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| Nanoparticles of BaSnO3 were incorporated into YBa2Cu3O7-x (YBCO) films on LaAlO3 substrates for magnetic flux pinning enhancements. More than an order of magnitude improvement in the high field magnetization Jc at 6 T at 77 K was observed as compared to regular YBCO films. The irreversibility field (Hirr) was increased to 8.5 T at 77 K and to 13.4 T at 65 K. The in-field transport current measurements confirmed an ... |
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| Multi-Core Processors: An Enabling Technology for Embedded Distributed Model-Based Control (Postprint) |
01-Jul-2008 |
13 pages |
| Authors:
Alireza Behbahani; Nathan Gibson; Murali Rangarajan; Dewey Benson; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIRECTORATE
|
| Multi-core processing technology has been developing rapidly and multi-core solutions are becoming increasingly prevalent in industry. The potential impact and disruption of multi-core technologies to centralized computationally intensive applications, such as engine control, may be significant. With the ability to efficiently partition code between separate processing elements, whilst sharing a common I/O space, a new generation of process partitioning, a thread pipelining becomes possible. In this paper we briefly summarize ... |
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| Communication Needs Assessment for Distributed Turbine Engine Control (Postprint) |
01-Jul-2008 |
16 pages |
| Authors:
Dennis E Culley; Alireza R Behbahani; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIRECTORATE
|
| Control system architecture is a major contributor to future propulsion engine performance enhancement and life cycle cost reduction. The control system architecture can be a means to effect net weight reduction in future engine systems, provide a streamlined approach to system design and implementation, and enable new opportunities for performance optimization and increased awareness about system health. The transition from a centralized, point-to-point analog control topology to a modular, networked, ... |
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| Sensing Challenges for Controls and PHM in the Hostile Operating Conditions of Modern Turbine Engine (Postprint) |
01-Jul-2008 |
14 pages |
| Authors:
Alireza Behbahani; Kenneth Semega; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIRECTORATE
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| Advanced gas turbine engines have evolved over the last several decades to dominate aviation's propulsion, commercial and the military market. Continuing engine performance and reliability advances will require sensor components that operate reliably under extreme engine operating conditions (e.g., takeoff, max thrust) and in harsh environments (e.g., high temperature and radiation). The design of advanced controls and Propulsion Health Management (PHM) will also depend on the use of components with ... |
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| Jet Engine Control Using Ethernet with a BRAIN (Postprint) |
01-Jul-2008 |
20 pages |
| Authors:
Alireza Behbahani; Dewey Benson; Brendan Hall; Michael Paulitsch; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIRECTORATE
|
| Distributed control architectures are becoming increasingly prevalent as smart actuation and sensing technology becomes more cost-effective and realizable. However, achieving a distributed architecture that supports the increasing computational demands of engine control and prognostics strategies whilst surviving in the harsh on-engine environment remains to be a significant challenge. In this paper we present a Hybrid Ethernet based architecture that combines gigabit per second capacity for computational agreement and replication, with ... |
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| Initial Characterization of Three-Dimensional Flow Separation in a Compressor Stator (Preprint) |
01-Jun-2008 |
16 pages |
| Authors:
S T Bailie; Grant A Hile; Steven L Puterbaugh; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIRECTORATE
|
| A research program is underway seeking to effect a net decrease in aerodynamic loss of a moderately loaded axial compressor stator passage across varying operating conditions. Three dimensional boundary layer separation, typical at the suction surface corners, can differ greatly from classical two dimensional separation, and is the dominant loss and blockage generating feature in the diffusing flowfield of compressor stators. The initial research phase is presently described, wherein a ... |
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| Experimental Studies of Pylon-Aided Fuel Injection into a Supersonic Crossflow |
01-May-2008 |
13 pages |
| Authors:
Kuang-Yu Hsu; Mark R Gruber; Campbell D Carter; Daniel R Montes; Lane C Haubelt; Paul I King; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIRECTORATE
|
| An investigation of the nonreacting flow associated with pylon-aided gaseous fuel injection into a Mach 2 crossflow is described. In this study, a small pylon was positioned just upstream of a circular flush-wall fuel injector. Three pylon geometries were studied, along with a no-pylon reference case. In all cases, a typical cavity-based flameholder was positioned downstream of the fuel injector. The injectant plume characteristics were interrogated using a variety of ... |
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| Design Strategies to Mitigate Unsteady Forcing (Preprint) |
APR 2008 |
56 pages |
| Authors:
John P. Clark; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIRECTORATE
|
| The ability to predict accurately the levels of unsteady forcing on turbine blades is critical to avoid high-cycle fatigue failures. Further, a demonstrated ability to make accurate predictions leads to the possibility of controlling levels of unsteadiness through aerodynamic design. Several ingredients were essential to the success achieved in this study. First, judicious post-processing of CFD solutions was required to ensure that proper periodicity was achieved, and this was contingent ... |
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| Transient Plasma Induced Production of OH and its Effects on Ignition in Atmospheric CH4-AIR Quiescent Mixtures (Postprint) |
JAN 2008 |
12 pages |
| Authors:
Charles Cathey; Jeremy Cain; Hai Wang; Martin A. Gundersen; Michael Ryan; Campbell D. Carter; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIRECTORATE
|
| Transient plasma from a 60 kV, 70 ns pulse induced OH production in air and CH4/air quiescent mixtures inside a cylindrical chamber is analyzed. The resulting OH from the plasma discharge, ignition, and subsequent combustion is analyzed using planar laser induced fluorescence. A high-framing-rate camera was also used to image ignition and flame propagation in the chamber, providing spatial and temporal resolution over the entire combustion event. Results indicate OH ... |
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| Polyarylenethioethersulfone Membranes for Fuel Cells (Postprint) |
SEP 2007 |
12 pages |
| Authors:
Stanley J. Rodrigues; Thomas L. Reitz; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIRECTORATE
|
| High performance, sulfonated polyarylenethioethersulfone (SPTES) polymers have been developed as membranes for fuel cells. These high molecular weight polymers synthesized by a polycondensation process have an aromatic backbone along with high sulfonic acid content that provides for their high conductivity and robust mechanical properties. Bulky phenyl-based end-capping agents are incorporated into the system to maintain high water stability and retain high proton conductivity. Films with good mechanical properties were obtained ... |
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| Evaluation of Catalytic and Thermal Cracking in a JP-8 Fueled Pulsed Detonation Engine (Postprint) |
SEP 2007 |
15 pages |
| Authors:
Timothy M. Helfrich; Frederick R. Schauer; Royce P. Bradley; John L. Hoke; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIRECTORATE
|
| Pulsed detonation engines (PDEs) depend on rapid ignition and transition from deflagration to detonation. The prospect of converting the PDE from experimental to operational use necessitates a considerable reduction in the time required to ignite and detonate a liquid hydrocarbon fuel in air, such as JP-8. This research effort is focused on PDE operation enhancements using dual detonation tube, concentric-counter-flow heat exchangers to elevate the fuel temperature levels sufficiently to ... |
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| Advanced, Adaptive, Modular, Distributed, Generic Universal FADEC Framework for Intelligent Propulsion Control Systems (Preprint) |
SEP 2007 |
48 pages |
| Authors:
Alireza R. Behbahani; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIRECTORATE
|
| Today, each FADEC is unique and expensive to develop, produce, maintain, and upgrade for its particular application. Each FADEC is a centralized system, with a redundant, central computer and centrally located analog signal interfacing circuitry for interfacing with sensors and actuators located throughout the propulsion system. It is to establish a universal or common standard for engine controls and accessories. This will significantly reduce the high development and support costs ... |
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| Influence of an Additional Ballast Volume on a Pulsed ICP Discharge (Postprint) |
10 AUG 2007 |
8 pages |
| Authors:
E. A. Bogdanov; Jr. DeJoseph C. A.; V. I. Demidov; A. A. Kudryavtsev; K. Yu. Serditov; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIRECTORATE
|
| A spatial and temporal numerical simulation has been carried out of a pulsed (100% modulated), rf inductively coupled plasma discharge in argon, connected to an additional (ballast) diffusion chamber of much larger volume. It is demonstrated that during the active phase, the presence of the large ballast volume has a small impact on the parameters of the plasma in the smaller discharge chamber. In this case the plasma parameters in ... |
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| The Effect of Steady Fluid Motion on One-Dimensional Wave Propagation (Postprint) |
AUG 2007 |
13 pages |
| Authors:
Barry Kiel; Reza Kashani; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIRECTORATE
|
| Reduced order modeling of thermoacoustic instabilities involves the coupled modeling of the wave propagation in the combustion chamber and the unsteady heat release. In many combustion systems the Mach number is low enough that the effect of the fluid motion on the wave propagation can be ignored. Ignoring the fluid motion results in the use of the wave equation to model the wave motion in the combustion chamber. In a ... |
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| Non-Reacting and Combusting Flow Investigation of Bluff Bodies in Cross Flow (Postprint) |
AUG 2007 |
13 pages |
| Authors:
Barry Kiel; Kyle Garwick; Amy Lynch; James R. Gord; Terrence Meyer; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIRECTORATE
|
| This paper is the first in a series of papers studying the behavior of bluff body stabilized flames. In this research a combination of Laser Doppler Velocimetry (LDV), and High Speed Imaging are used to investigate these flames. LDV data taken over several non-combusting operating conditions detail the recirculation zone behind the bluff body as well as the effect of inlet conditions on the Karman Street vortex shedding that occurs. ... |
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| Improved Correlations for Augmentor Static Stability (Postprint) |
AUG 2007 |
12 pages |
| Authors:
Barry V. Kiel; Darin A. Knaus; Patrick J. Magari; Roger W. Hill; Scott D. Phillips; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIRECTORATE
|
| Flame stability is critical to the operational performance of combustion systems in propulsion and power generation. Current predictive tools for flame stability are based on decades-old empirical correlations that have limited applicability for modern combustor designs. Recent advances in computational fluid dynamics (CFD) and advanced combustion diagnostics have provided new insight into the fundamental processes that occur in these flows. Reacting-flow CFD has yet to mature to a level where ... |
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| A Detailed Investigation of Bluff Body Stabilized Flames (Postprint) |
AUG 2007 |
12 pages |
| Authors:
Barry Kiel; Kyle Garwick; James R. Gord; Joseph Miller; Amy Lynch; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIRECTORATE
|
| Reduced Order Models (ROMs) and Computational Fluid Dynamics (CFD) codes are tools used to predict the extinction of flames behind bluff bodies. Accurate prediction of these models and codes is predicated on their validation with experimental data. This paper describes detailed experiments to obtain validation data for bluff body stabilized flames over a wide range of conditions. Included are non-reacting data from CFD and LDV, lean blowout and high speed ... |
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| Operability and Efficiency Performance of Ultra-Compact, High Gravity (g) Combustor Concepts (Postprint) |
JUL 2007 |
11 pages |
| Authors:
Joseph Zelina; Roger T. Greenwood; Dale T. Shouse; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIRECTORATE
|
| This paper presents a parametric design study of the Ultra-Compact Combustor (UCC), a novel design based on trapped-vortex combustor (TVC) work that uses high swirl in a circumferential cavity to enhance reaction rates via high cavity g-loading on the order of 3000 g's. Increase in reaction rates translates to a reduced combustor volume. Three combustor geometric features were varied during experiments which included (1) high-g cavity flame-holding method, (2) high-g ... |
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| Growth and Characterization of Carbon Nanotubes on Constantan (Cu-Ni-Mn Alloy) Metallic Substrates Without Adding Additional Catalysts |
Jul-2007 |
6 pages |
| Authors:
J Burke; L Brunke; J Bulmer; J Baca; K Yost; P Barnes; C V Varanasi; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIRECTORATE
|
| In this study, metallic constantan (Cu55-Ni44-Mn1 wt %) alloy substrates were investigated as an alternate choice of substrates to grow carbon nanotubes (CNTs). No additional catalysts were used other than the as-rolled and annealed substrates to process CNTs on them. High density CNT growth was observed to take place on these substrates when suitable conditions were used in a thermal chemical vapor deposition (CVD) furnace with C2H2 as the carbon ... |
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| The Effects of Space Charge in a Hypersonic Magnetohydrodynamic Power Generator |
JUN 2007 |
34 pages |
| Authors:
Rene J. Thibodeaux; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIRECTORATE
|
| This paper explores a new MHD generator design that uses space charge to create an axial-symmetric electric field in the region between concentrically cylindrical channels. The space charge fraction is shown to have a significant effect in the current density, power density, electric field, output voltage, efficiency, pressure drop, and enthalpy. The radial symmetry produces simple analytic solutions for these equations over a wide range of gas flow speeds. Adjustments ... |
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| Adaptive Distributed Intelligent Control Architecture for Future Propulsion Systems (Preprint) |
APR 2007 |
51 pages |
| Authors:
Alireza R. Behbahani; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIRECTORATE
|
| Adaptive Distributed Control System (ADCS) architectures have been developing rapidly in all fields to provide for optimal control, prognosis and safety-critical systems. Concepts such as controller decentralization and "smart" sensor/actuators have been studied by both government agencies and industry. Distributed control is potentially an enabling technology for advanced intelligent propulsion system concepts and is one of the few control approaches that is able to provide improved component and control system ... |
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| An Integrated Approach to Conversion, Verification, Validation and Integrity of AFRL Generic Engine Model and Simulation (Postprint) |
FEB 2007 |
38 pages |
| Authors:
Jeffrey S. Dalton; Al Behbahani; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIRECTORATE
|
| Modern airborne weapons systems face increasingly stringent demands for improved performance and lower cost of ownership. The key to attaining the first of these demands is increased sub-systems integration, which leverages improved component performance to make even greater improvements in overall weapons system capability. Research is essential to gaining a fundamental understanding of the behavior and control of these highly integrated systems. Progress towards meeting the affordability demands for these ... |
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| A Feasibility Study of Life-Extending Controls for Aircraft Turbine Engines Using a Generic Air Force Model (Preprint) |
DEC 2006 |
9 pages |
| Authors:
Al Behbahani; Eric A. Jordan; Richard Millar; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIRECTORATE
|
| Turbine engine controllers are typically designed and operated to meet required or desired performance criterion within stability margins, while maximizing fuel efficiency. The U.S. Air Force turbine engine research program is seeking to incorporate sustainable cost reduction into this approach, by considering a life-cycle design objective if the life of the engine is considered as an objective during the design of the engine controller. Specifically during aircraft takeoff, the turbine ... |
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| Effects of Corona, Spark and Surface Discharges on Ignition Delay and Deflagration-to-Detonation Times in Pulsed Detonation Engines (Postprint) |
DEC 2006 |
12 pages |
| Authors:
Kenneth Busby; Jennifer Corrigan; Sheng-Tao Yu; Skip Williams; Campbell Carter; Frederick Schauer; John Hoke; Charles Cathey; Martin Gundersen; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIRECTORATE
|
| The purpose of the research described herein is to compare the ignition delays in an experimental pulsed detonation engine produced by thermal and non-thermal ignitions. The commercial thermal ignition has a pulse duration of about 1 microsec, whereas the non-thermal ignitions have pulse durations of 100 nanosec. Ignition delay is an important factor, along with fill and purge times, that limit the maximum repetition rate and thrust of pulsed detonation ... |
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| Aircraft Battery Design Concept for Improved Ultra Low Temperature Performance (Postprint) |
NOV 2006 |
6 pages |
| Authors:
John K. Erbacher; Gary J. Loeber; Sarah M. Owens; Cameron A. Riepenhoff; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIRECTORATE
|
| The AFRL, Electrochemistry and Thermal Sciences Branch has evaluated numerous aircraft battery designs and chemistries since the 1960s. Recent experiments on advanced battery chemistries have shown poor performance at ultra low temperatures below -20 deg C. Aircraft battery designs stress low weight and volume and maximum capacity. One design concept uses lower capacity cells in a series parallel configuration to reduce overall battery resistance and should also improve ultra low ... |
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| Achieving AFRL Universal FADEC Vision With Open Architecture Addressing Capability and Obsolescence for Military and Commercial Applications (Preprint) |
NOV 2006 |
49 pages |
| Authors:
Alireza R. Behbahani; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIRECTORATE
|
| The United States Air Force (USAF) has over 24,000 aircraft which include over 47,000 turbine engines. The aircraft systems are expensive and must be routinely modernized or upgraded to keep pace with threats, missions, and advancing technology. Each modern turbine engine includes controls and accessories which cost about 1/5 of the total cost of an engine. The main component of controls and accessories are the Full Authority Digital Engine Controls ... |
|
| Centrifuge Testing of a Partially-Confined FC-72 Spray |
NOV 2006 |
7 pages |
| Authors:
Levi J. Elston; Kirk L. Yerkes; Andrew J. Fleming; Scott K. Thomas; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIRECTORATE
|
| The effects of elevated acceleration fields on spray cooling heat transfer are discussed in this paper. Spray cooling has proven to be one of the most efficient methods of heat removal. This technology is being transitioned into more advanced applications, such as fighter aircraft that must withstand a wide range of variable acceleration-induced body forces. Heat transfer associated with closed-loop spray cooling will be affected by acceleration body forces, the ... |
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| Aircraft Thermal Management Using Loop Heat Pipes: Experimental Simulation of High Acceleration Environments Using the Centrifuge Table Test Bed (Postprint) |
NOV 2006 |
12 pages |
| Authors:
Andrew J. Fleming; Quinn H. Leland; Kirk L. Yerkes; Levi J. Elston; Scott K. Thomas; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIRECTORATE
|
| The objective of this paper is to describe the design of an experiment that will examine the effects of elevated acceleration environments on a high-temperature, titanium-water loop heat pipe for actuator cooling. An experimental test setup has been designed for mounting a loop heat pipe on an 8-ft-diameter centrifuge table, which is capable of radial accelerations of up to 12-g's. A high-temperature PAO loop will interface the condenser of the ... |
|
| An Experimental Investigation of Low-Pressure Turbine Blade Suction Surface Stresses Using S3F (Preprint) |
OCT 2006 |
14 pages |
| Authors:
Mark McQuilling; Mitch Wolff; Sergey Fonov; Jim Crafton; Rolf Sondergaard; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIRECTORATE
|
| A shear and stress sensitive film (S3F) is employed on the suction surface of an industry standard low-pressure turbine blade. These tests address the optimization of S3F for low-speed air investigations on a curved surface, and are the first measurements of its kind. S3F provides all three stress components on a surface in a single measurement, and is based on 3D elastic deformations of a polymeric film. New composition films ... |
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| Measured Properties of Turbulent Premixed Flames for Model Assessment, Including Burning Velocities, Stretch Rates, and Surface Densities (Postprint) |
OCT 2006 |
23 pages |
| Authors:
Sergei A. Filatyev; James F. Driscoll; Campbell D. Carter; Jeffrey M. Donbar; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIRECTORATE
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| One goal of this work was to quantify several properties of turbulent premixed flames that have not been quantified before and are especially useful for the assessment of direct numerical simulations (DNS) and models. It was decided to select a flame that is in the corrugated flamelet regime and use simultaneous CH planar laser-induced fluorescence/ particle image velocimetry (CH PLIF/PIV) diagnostics, which previously had been applied only to nonpremixed combustion. ... |
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| Diode Laser Diagnostics of High Speed Flows (Postprint) |
OCT 2006 |
17 pages |
| Authors:
Skip Williams; Dominic Barone; Todd Barhorst; Kevin Jackson; K. C. Lin; Pat Masterson; Qingchun Zhao; Andrew D. Sappey; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIRECTORATE
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| This document contains the specific requirements and preliminary results for the Optical Mass Capture (OMC) experiment for the Fundamental RESearch Hypersonic Flight experimentation (FRESH Fx) program. The objective of this effort is to develop and demonstrate in flight a diode-laser-based measurement of engine air mass capture in the inlet or isolator of a hypersonic vehicle over an altitude range of 60,000-90,000 ft with an average Mach number of 7.5 over ... |
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| Performance Impacts Due to Wake in Axil-Flow Turbomachinery (Postprint) |
SEP 2006 |
12 pages |
| Authors:
T. J. Praisner; J. P. Clark; T. C. Nash; M. J. Rice; E. A. Grover; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIRECTORATE
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| Here, we demonstrate that the unsteady losses incurred as turbomachinery wakes mix in downstream rows are a function of the velocity ratio across the downstream row as calculated in the frame of reference of wake generation. Analytical and computational results, compared to measurements of wakes mixing under variable free-stream velocity conditions, reveal that wake-loss alteration is primarily a result of an inviscid dilation of the stream tubes that comprise the ... |
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| Need for Robust Sensors for Inherently Fail-Safe Gas Turbine Engine Controls, Monitoring, and Prognostics (Postprint) |
SEP 2006 |
37 pages |
| Authors:
Alireza R. Behbahani; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIRECTORATE
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| Sensor reliability is critical to turbine engine control. Today's aircraft engines demand more sophisticated sensors in the control systems, requiring advanced engine testing for component performance demonstration. Expertise in the gas turbine instrumentation community is located across the gas turbine industry itself, within several specialized university departments serving to supplement the more general research programs in gas turbine research. Sensor technology has advanced in many fields; however, implementation has been ... |
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| A Novel Temperature Measurement Approach for a High Pressure Dielectric Barrier Discharge Using Diode Laser Absorption Spectroscopy (Preprint) |
SEP 2006 |
18 pages |
| Authors:
R. J. Leiweke; B. N. Ganguly; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIRECTORATE
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| A tunable diode laser absorption spectroscopic technique is used to measure both electronically excited state production efficiency and gas temperature rise in a dielectric barrier discharge in argon. The effect of voltage pulse rise time on the power deposition and electronically excited state production efficiency have been measured over a operating pressure range from 100 Torr up to 500 Torr. |
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| Magnetization Losses in Multifilament Coated Superconductors (Postprint) |
AUG 2006 |
5 pages |
| Authors:
G. A. Levin; P. N. Barnes; N. Amemiya; S. Kasai; K. Yoda; Z. Jiang; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIRECTORATE
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| We report the results of a study of the magnetization losses in experimental multifilament, as well as control (uniform) coated superconductors exposed to time-varying magnetic fields of various frequencies. Both the hysteresis loss, proportional to the sweep rate of the applied magnetic field, and the coupling loss, proportional to the square of the sweep rate, have been observed. A scaling is found that allows us to quantify each of these ... |
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| Rechargeable Lithium-Ion Based Batteries and Thermal Management for Airborne High Energy Electric Lasers (Preprint) |
AUG 2006 |
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| Authors:
Joseph P. Fellner; Ryan M. Miller; Venkatrama Shanmugasundaram; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIRECTORATE
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 | Advances in the past decade of the energy and power densities of lithium-ion based batteries for hybrid electric vehicles and various consumer applications have been substantial. Rechargeable high rate lithium-ion batteries are now exceeding 6 kW/kg for short discharge times 160 Whr/kg at > 1.0 kW/kg). Some preliminary test data on a rechargeable lithium-ion polymer battery is presented. The use of high rate rechargeable lithium-ion batteries as a function of ... |
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| Design of A Microgravity Spray Cooling Experiment |
JUL 2006 |
14 pages |
| Authors:
Kerri M. Basinger; Kirk L. Yerkes; Travis E. Michalak; Richard J. Harris; John McQuillen; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIRECTORATE
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| An analytical and experimental study was conducted for the application of spray cooling in a micro gravity and high-g environment. Experiments were carried out aboard the NASA KC-135 reduced gravity aircraft, which provided both the microgravity and high-g environments. In reduced gravity, surface tension flow was observed around the spray nozzle, due to unconstrained liquid in the test chamber and flow reversal at the heat source. A transient analytical model ... |
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