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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 613 records · Page 34
All sourcesNASA NTRSDOE OSTI
NASA NTRS1990

The 27-28 October 1986 FIRE cirrus case study: Meteorology and clouds

Detailed descriptions of the rawinsonde resolved meteorological conditions (3 hourly soundings) associated with a succession of five distinct mesoscale cirrus cloud regimes, that were intensively observed over a 36 hour period, are given. The synoptic scale systems in which these features were embedded are described and a brief overview of the experiment is given. Regional analyses of the static stability structure and vertical motion are presented and interpreted with respect to the characteristics of the corresponding cloud fields as deduced from satellite and lidar observations. The cloud fields exhibited a high degree of persistent mesoscale organization on scales of 20 to 500 km reflecting corresponding scales of dynamic and thermodynamic structure/variability as on the synoptic scale. Cloud generation was usually confined to layers less than 1 km deep (typically 0.5 km in depth) and cellular organization was evident in most cases irrespective of the thermal stratification. Multilayered development was prevalent (2 to 3 layers) and was associated with vertical structure of the temperature and moisture fields resulting primarily from vertical gradients in horizontal advection.

Starr, David↗
NASA NTRS1990

O-THREE: A high altitude, remotely piloted vehicle

A conceptual design for a remotely piloted vehicle to be used for ozone research above 80,000 feet was developed as part of the one-semester NASA/Universities Space Research Association Aerospace Design course at Case Western Reserve University in Fall 1989. The O-Three design team chose as its mission requirements a cruise altitude of 100,000 ft, a range of 1000 n.m., an endurance of 6 hrs., a 1000 lb payload, and a power to payload of 2 kW. These are based on the Boeing requirements for an ozone research vehicle. In addition, the vehicle should not be restricted to operation over any particular global location. Efforts were made to minimize atmospheric contamination that might increase the rate of ozone depletion and cause discrepancies in data accuracy. Design was not limited to today's level of technology. The design team was divided into four groups: aerodynamics, structures, stability, and control. The specifications and performance estimates for cruise at altitude are given in tabular form.

Source record↗
NASA NTRS1992

High-Temperature Treatments For Polyimide/Graphite Composite

Combination of inert-gas heat treatment and coating with material impermeable by oxygen proposed to increase thermo-oxidative and high-temperature structural stabilities of composite materials made of graphite fibers in matrices of PMR-15 polyimide. Proposal directed toward development of lightweight matrix/fiber composites for use in aircraft engines, wherein composites exposed to maximum operating temperatures between 371 and 427 degrees C.

Bowles, Kenneth J.↗
NASA NTRS1992

Thermophilic Beta-Glycosidase

Report describes identification of thermophilic Beta-glycosidase enzyme from isolate of Sulfolobus solfataricus, sulfur-metabolizing archaebacteria growing aerobically and heterotrophically to relatively high cell yields. Enzyme useful in enzymatic conversion of cellulose to D-glucose and important in recycling of biomass. Used for removal of lactose from milk products. Offers promise as model substance for elucidation of basic principles of structural stabilization of proteins.

Grogan, Dennis W.↗
NASA NTRS1992

Eagle RTS: A design of a regional transport

The Eagle RTS (Regional Transport System) is a 66-passenger aircraft designed to satisfy the need for accessible and economical regional travel. The first design objective for the Eagle RTS is safety. Safety results primarily from avoidance of the hub airport air traffic, implementation of anti-stall characteristics by tailoring the canard, and proper positioning of the engines for blade shedding. To provide the most economical aircraft, the Eagle RTS will use existing technology to lower production and maintenance costs by decreasing the amount of new training required. In selecting the propulsion system, the effects on the environment were a main consideration. Two advantages of turbo-prop engines are the high fuel efficiency and low noise levels produced by this type of engine. This ensures the aircraft's usage during times of rising fuel costs and growing aircraft noise restrictions. The design of the Eagle RTS is for spoke-to-spoke transportation. It must be capable of landing on shorter runways and have speeds comparable to that of the larger aircraft to make its service beneficial to the airlines. With the use of turbo-prop engines and high lift devices, the Eagle RTS is highly adaptable to regional airports. The design topics discussed include: aerodynamics, stability, structures and materials, propulsion, and cost.

Bryer, Paul↗
NASA NTRS1993

Martian deltas: Morphology and distribution

Recent detailed mapping has revealed numerous examples of Martian deltas. The location and morphology of these deltas are described. Factors that contribute to delta morphology are river regime, coastal processes, structural stability, and climate. The largest delta systems on Mars are located near the mouths of Maja, Maumee, Vedra, Ma'adim, Kasei, and Brazos Valles. There are also several smaller-scale deltas emplaced near channel mouths situated in Ismenius Lacus, Memnonia, and Arabia. Delta morphology was used to reconstruct type, quantity, and sediment load size transported by the debouching channel systems. Methods initially developed for terrestrial systems were used to gain information on the relationships between Martian delta morphology, river regime, and coastal processes.

Rice, J. W., Jr.↗
NASA NTRS1994

Parallel aeroelastic computations for wing and wing-body configurations

The objective of this research is to develop computationally efficient methods for solving fluid-structural interaction problems by directly coupling finite difference Euler/Navier-Stokes equations for fluids and finite element dynamics equations for structures on parallel computers. This capability will significantly impact many aerospace projects of national importance such as Advanced Subsonic Civil Transport (ASCT), where the structural stability margin becomes very critical at the transonic region. This research effort will have direct impact on the High Performance Computing and Communication (HPCC) Program of NASA in the area of parallel computing.

Byun, Chansup↗
NASA NTRS1994

Development of a low-aspect ratio fin for flight research experiments

A second-generation flight test fixture, developed at NASA Dryden Flight Research Center, offers a generic testbed for aerodynamic and fluid mechanics research. The new fixture, a low-aspect ratio vertical fin shape mounted on the centerline of an F-15B aircraft lower fuselage, is designed for flight research at Mach numbers up to 2.0. The new fixture is a composite structure with a modular configuration and removable components for functional flexibility. This report describes the multidisciplinary design and analysis approach used to develop the fixture. The approach integrates conservative assumptions with simple analysis techniques to minimize the time and cost associated with its development. Presented are the principal disciplines required for this effort, which include aerodynamics, structures, stability, and operational considerations. In addition, preliminary results from the first phase of flight testing are presented. Acceptable directional stability and flow quality are documented and show agreement with predictions. Future envelope expansion activities will minimize current limitations so that the fixture can be used for a wide variety of high-speed aerodynamic and fluid mechanics research experiments.

Richwine, David M.↗
NASA NTRS1995

Aeroelasticity of wing and wing-body configurations on parallel computers

The objective of this research is to develop computationally efficient methods for solving aeroelasticity problems on parallel computers. Both uncoupled and coupled methods are studied in this research. For the uncoupled approach, the conventional U-g method is used to determine the flutter boundary. The generalized aerodynamic forces required are obtained by the pulse transfer-function analysis method. For the coupled approach, the fluid-structure interaction is obtained by directly coupling finite difference Euler/Navier-Stokes equations for fluids and finite element dynamics equations for structures. This capability will significantly impact many aerospace projects of national importance such as Advanced Subsonic Civil Transport (ASCT), where the structural stability margin becomes very critical at the transonic region. This research effort will have direct impact on the High Performance Computing and Communication (HPCC) Program of NASA in the area of parallel computing.

Byun, Chansup↗
NASA NTRS1996

Aeroservoelastic Modeling and Validation of a Thrust-Vectoring F/A-18 Aircraft

An F/A-18 aircraft was modified to perform flight research at high angles of attack (AOA) using thrust vectoring and advanced control law concepts for agility and performance enhancement and to provide a testbed for the computational fluid dynamics community. Aeroservoelastic (ASE) characteristics had changed considerably from the baseline F/A-18 aircraft because of structural and flight control system amendments, so analyses and flight tests were performed to verify structural stability at high AOA. Detailed actuator models that consider the physical, electrical, and mechanical elements of actuation and its installation on the airframe were employed in the analysis to accurately model the coupled dynamics of the airframe, actuators, and control surfaces. This report describes the ASE modeling procedure, ground test validation, flight test clearance, and test data analysis for the reconfigured F/A-18 aircraft. Multivariable ASE stability margins are calculated from flight data and compared to analytical margins. Because this thrust-vectoring configuration uses exhaust vanes to vector the thrust, the modeling issues are nearly identical for modem multi-axis nozzle configurations. This report correlates analysis results with flight test data and makes observations concerning the application of the linear predictions to thrust-vectoring and high-AOA flight.

Brenner, Martin J.↗
NASA NTRS1999

Lightweight Aluminum Mirrors Using Foam Core Sandwich Construction

The possible use of all aluminum mirrors made from thin faceplates supported by aluminum foam is explored from an optomechanical design and fabrication perspective. Foam mirrors can be relatively cheaply and easily made using conventional foam fabrication and diamond turning; such a mirror recently flew for the first time on the Stardust mission. The proposed structural concept is highly weight efficient and should not be prone to quilting. The weight and structural stability of such mirrors is presented, along with plans underway at GSFC for developing this concept.

Content, D.↗
NASA NTRS1998

Substrate Effects for Atomic Chain Electronics

A substrate for future atomic chain electronics, where adatoms are placed at designated positions and form atomically precise device components, is studied theoretically. The substrate has to serve as a two-dimensional template for adatom mounting with a reasonable confinement barrier and also provide electronic isolation, preventing unwanted coupling between independent adatom structures. For excellent structural stability, we demand chemical bonding between the adatoms and substrate atoms, but then good electronic isolation may not be guaranteed. Conditions are clarified for good isolation. Because of the chemical bonding, fundamental adatom properties are strongly influenced: a chain with group IV adatoms having two chemical bonds, or a chain with group III adatoms having one chemical bond is semiconducting. Charge transfer from or to the substrate atoms brings about unintentional doping, and the electronic properties have to be considered for the entire combination of the adatom and substrate systems even if the adatom modes are well localized at the surface.

Yamada, Toshishige↗
NASA NTRS1989

Scientific Toy

Tensegritoy, inspired by the tensegrity concepts of R. Buckminster Fuller, is an erector set like toy designed to give students an understanding of structural stability. It is used by children, architects, engineers, and teachers. The manufacturer, Tensegrity Systems Corporation, also offers a collapsible point of purchase display which incorporates technology developed for space station trusses described in "NASA Tech Briefs." The tech brief described deployable trusses that can be collapsed into small packages for space shuttle transport, then unfolded in space. As a result, the display occupies a minimum amount of floor space, freight cost savings are substantial and assembly can be completed quickly.

Source record↗
NASA NTRS2003

Diabatic Initialization of Mesoscale Models in the Southeastern United States: Can 0 to 12h Warm Season QPF be Improved?

It is well known that numerical warm season quantitative precipitation forecasts lack significant skill for numerous reasons. Some are related to the model--it may lack physical processes required to realistically simulate convection or the numerical algorithms and dynamics employed may not be adequate. Others are related to initialization-mesoscale features play an important role in convective initialization and atmospheric observation systems are incapable of properly depicting the three-dimensional stability structure at the mesoscale. The purpose of this study is to determine if a mesoscale model initialized with a diabatic initialization scheme can improve short-term (0 to 12h) warm season quantitative precipitation forecasts in the Southeastern United States. The Local Analysis and Prediction System (LAPS) developed at the Forecast System Laboratory is used to diabatically initialize the Pennsylvania State University/National center for Atmospheric Research (PSUNCAR) Mesoscale Model version 5 (MM5). The SPORT Center runs LAPS operationally on an hourly cycle to produce analyses on a 15 km covering the eastern 2/3 of the United States. The 20 km National Centers for Environmental Prediction (NCEP) Rapid Update Cycle analyses are used for the background fields. Standard observational data are acquired from MADIS with GOES/CRAFT Nexrad data acquired from in-house feeds. The MM5 is configured on a 140 x 140 12 km grid centered on Huntsville Alabama. Preliminary results indicate that MM5 runs initialized with LAPS produce improved 6 and 12h QPF threat scores compared with those initialized with the NCEP RUC.

Lapenta, William M.↗
NASA NTRS1999

Modeling the unidentified infrared emission with combinations of polycyclic aromatic hydrocarbons

The infrared emission band spectrum associated with many different interstellar objects can be modeled successfully by using combined laboratory spectra of neutral and positively charged polycyclic aromatic hydrocarbons (PAHs). These model spectra, shown here for the first time, alleviate the principal spectroscopic criticisms previously leveled at the PAH hypothesis and demonstrate that mixtures of free molecular PAHs can indeed account for the overall appearance of the widespread interstellar infrared emission spectrum. Furthermore, these models give us insight into the structures, stabilities, abundances, and ionization balance of the interstellar PAH population. These, in turn, reflect conditions in the emission zones and shed light on the microscopic processes involved in the carbon nucleation, growth, and evolution in circumstellar shells and the interstellar medium.

Spectrophotometry, Infrared↗
NASA NTRS1989

Effects of microgravity on liposome-reconstituted cardiac gap junction channeling activity

Effects of microgravity on cardiac gap junction channeling activity were investigated aboard NASA zero-gravity aircraft. Liposome-reconstituted gap junctions were assayed for channel function during free-fall, and the data were compared with channeling at 1 g. Control experiments tested for 0 g effects on the structural stability of liposomes, and on the enzyme-substrate signalling system of the assay. The results demonstrate that short periods of microgravity do not perturb reconstituted cardiac gap junction channeling activity.

Heart/physiology↗
NASA NTRS2003

Regulation, Competition and Network Evolution in Aviation

Our focus is the evolution of business strategies and network structure decisions in the commercial passenger aviation industry. The paper reviews the growth of hub-and-spoke networks as the dominant business model following deregulation in the latter part of the 20 century, followed by the emergence of value-based airlines as a global phenomenon at the end of the century. The paper highlights the link between airline business strategies and network structures, and examines the resulting competition between divergent network structure business models. In this context we discuss issues of market structure stability and the role played by competition policy.

Gillen, David↗
NASA NTRS2003

Field Effects of Buoyancy on a Premixed Turbulent Flame Studied by Particle Image Velocimetry

Typical laboratory flames for the scientific investigation of flame/turbulence interactions are prone to buoyancy effects. Buoyancy acts on these open flame systems and provides upstream feedbacks that control the global flame properties as well as local turbulence/flame interactions. Consequently the flame structures, stabilization limits, and turbulent reaction rates are directly or indirectly coupled with buoyancy. The objective of this study is to characterize the differences between premixed turbulent flames pointing upwards (1g), pointing downwards (-1g), and in microgravity (mg). The configuration is an inverted conical flame stabilized by a small cone-shaped bluff body that we call CLEAN Flames (Cone-Stabilized Lean Flames). We use two laser diagnostics to capture the velocity and scalar fields. Particle image velocimetry (PIV) measures the mean and root mean square velocities and planar imaging by the flame fronts method outlines the flame wrinkle topology. The results were obtained under typical conditions of small domestic heating systems such as water heaters, ovens, and furnaces. Significant differences between the 1g and -1g flames point to the need for including buoyancy contributions in theoretical and numerical calculations. In Earth gravity, there is a complex coupling of buoyancy with the turbulent flow and heat release in the flame. An investigation of buoyancy-free flames in microgravity will provide the key to discern gravity contributions. Data obtained in microgravity flames will provide the benchmark for interpreting and analyzing 1g and -1g flame results.

Cheng, Robert K.↗