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Report describes first phase of study of behavior of droplets of liquid fuels and oxidants in dense and dilute regions of sprays. Conducted in effort to understand evaporation and combustion of sprayed liquid fuels at both atmospheric and higher pressures.
Pressure sensitive paint is a newly-developed optical measurement technique with which one can get a continuous pressure distribution in much shorter time and lower cost than a conventional pressure tap measurement. However, most of the current pressure sensitive paint applications are restricted to steady pressure measurement at high speeds because of the small signal-to-noise ratio at low speed and a slow response to pressure changes. In the present study, three phases of work have been completed to extend the application of the pressure sensitive paint technique to low-speed testing and to investigate the applicability of the paint technique to unsteady flow. First the measurement system using a commercially available PtOEP/GP-197 pressure sensitive paint was established and applied to impinging jet measurements. An in-situ calibration using only five pressure tap data points was applied and the results showed good repeatability and good agreement with conventional pressure tap measurements on the whole painted area. The overall measurement accuracy in these experiments was found to be within 0.1 psi. The pressure sensitive paint technique was then applied to low-speed wind tunnel tests using a 60 deg delta wing model with leading edge blowing slots. The technical problems encountered in low-speed testing were resolved by using a high grade CCD camera and applying corrections to improve the measurement accuracy. Even at 35 m/s, the paint data not only agreed well with conventional pressure tap measurements but also clearly showed the suction region generated by the leading edge vortices. The vortex breakdown was also detected at alpha=30 deg. It was found that a pressure difference of 0.2 psi was required for a quantitative pressure measurement in this experiment and that temperature control or a parallel temperature measurement is necessary if thermal uniformity does not hold on the model. Finally, the pressure sensitive paint was applied to a periodically changing pressure field with a 12.8s time period. A simple first-order pole model was applied to deal with the phase lag of the paint. The unsteady pressure estimated from the time-changing pressure sensitive paint data agreed well with the pressure transducer data in regions of higher pressure and showed the possibility of extending the technique to unsteady pressure measurements. However, the model still needs further refinement based on the physics of the oxygen diffusion into the paint layer and the oxygen quenching on the paint luminescence.
The solid phase thermal reaction chemistry of NTO between 190 and 250 C is presently being evaluated by utilizing STMBMS, a technique that enables the authors to measure the vapor pressure of NTO and to explore the reaction mechanisms and chemical kinetics associated with the NTO thermal decomposition process. The vapor pressure of NTO is expressed as Log(sub 10) p(torr) = 12.5137 + 6,296.553(1/t(k)) and the Delta-H(sub subl) = 28.71 +/- 0.07 kcal/mol (120.01 +/- 0.29 kJ/mol). The pyrolysis of NTO results in the formation of gaseous products and a condensed-phase residue. The identity of the major gaseous products and their origin from within the NTO molecules are determined based on the results from pyrolysis of NTO, NTO-3-C-13, NTO-1,2- (15)N2 and NTO-(2)H2. Identification of the products show the major gaseous products to be N2, CO2, NO, HNCO, H2O and some N2O, CO, HCN and NH3. The N2 is mostly derived from the N-1 and N-2 positions with some being from the N-4 and N-1 or N-2 positions. The CO2 is derived from both carbons in the NTO molecule in comparable amounts. The residue has an elemental formula of C(2.1)H(.26)N(2.9)O and FTIR analysis suggests that the residue is polyurea- and polycarbamate- like in nature. The temporal behaviors of the rates of formation of the gaseous products indicate that the overall thermal decomposition of NTO in the temperature range evaluated involves four major processes: (1) NTO sublimation; (2) an apparent solid-solid phase transition between 190 and 195 C; (3) a decomposition regime induced by the presence of exogenous H2O at the onset of decomposition; and (4) a decomposition regime that occurs at the onset of decomposition and continues until the depletion of NTO. Decomposition pathways that are consistent with the data are presented.
As a follow-on to the spectacular success of the Hubble Space Telescope (HST), NASA is currently conducting pre-phase A studies of an even larger aperture telescope, called NGST (Next Generation Space Telescope), that will continue the phenomenal flow of astrophysical discoveries well into the next millennium. Because of the very large aperture required, current NGST concepts have been driven to elaborate schemes of foldable ultra thin and ultra light mirror segment systems that can be deployed on orbit. Due to the complexity of these optical systems, it is imperative that adequate demonstration experiments be flown to verify these new technology concepts before committing to the final design and implementation of the NGST. This paper presents a proposal for a very simple, inexpensive Hitchhiker flight experiment that will determine gravity release effects on very thin mirror segments made from current competitive materials. These experiments will provide the initial data that will be needed before more extensive demonstration flights of the NGST system can be flown.
NASA continues to focus on improving safety and reliability while reducing the annual cost of meeting human space flight and unique ISS and exploration needs. NASA's Space Transportation Architecture Study (STAS) Phase 2 in early 1998 focused on space transportation options. Subsequently, NASA directed parallel industry and government teams to conduct the Integrated Space Transportation Plan effort (STAS Phase 3). The objective of ISTP was to develop technology requirements, roadmaps, and risk reduction portfolio that considered expanded definition of "clean-sheet" and Shuttle-derived second generation ETO transportation systems in support of a 2005 RLV competition for NASA missions beginning 2010. NASA provided top-level requirements for improvements in safety, reliability, and cost and a set of design reference missions representing NASA ISS, human exploration, commercial, and other civil and government needs. This paper addresses the challenges of meeting NASA's objectives while servicing the varied market segments represented in the ISTP design reference missions and provides a summary of technology development needs and candidate system concepts. A comparison of driving requirements, architectures and technology needs is discussed and descriptions of viable Shuttle-derived and next generation systems to meet the market needs are presented.
The High-Lift Flight Tunnel (HiLiFT) concept is a revolutionary approach to aerodynamic ground testing. This concept utilizes magnetic levitation and linear motors to propel an aerodynamic model through a tube containing a quiescent test medium. This medium (nitrogen) is cryogenic and pressurized to achieve full flight Reynolds numbers higher than any existing ground test facility world-wide for the range of 0.05 to 0.50 Mach. The results of the Phase II study provide excellent assurance that the HiLiFT concept will provide a valuable low-speed, high Reynolds number ground test facility. The design studies concluded that the HiLiFT facility is feasible to build and operate and the analytical studies revealed no insurmountable difficulties to realizing a practical high Reynolds number ground test facility. It was determined that a national HiLiFT facility, including development, would cost approximately $400M and could be operational by 2013 if fully funded. Study participants included National Aeronautics and Space Administration Langley Research Center as the Program Manager and MSE Technology Applications, Inc., (MSE) of Butte, Montana as the prime contractor and study integrator. MSE#s subcontractors included the University of Texas at Arlington for aerodynamic analyses and the Argonne National Laboratory for magnetic levitation and linear motor technology support.
Lockheed Martin made a smooth transition from RCRA Facility Investigation (RFI) at the National Aeronautics and Space Administrations'(NASA) Michoud Assembly Facility (MA-F) to its Corrective Measures Study (CMS) phase within the RCRA Corrective Action Process. We located trichloroethylene (TCE) contamination that resulted from the manufacture of the Apollo Program Saturn V rocket and the Space Shuttle External Tank, began the cleanup, and identified appropriate technologies for final remedies. This was accomplished by establishing a close working relationship with the state environmental regulatory agency through each step of the process, and resulted in receiving approvals for each of those steps. The agency has designated Lockheed Martin's management of the TCE-contamination at the MAF site as a model for other manufacturing sites in a similar situation. In February 1984, the Louisiana Department of Environmental Quality (LDEQ) issued a compliance order to begin the clean up of groundwater contaminated with TCE. In April 1984 Lockheed Martin began operating a groundwater recovery well to capture the TCE plume. The well not only removes contaminants, but also sustains an inward groundwater hydraulic gradient so that the potential offsite migration of the TCE plume is greatly diminished. This effort was successful, and for the agency to give orders and for a regulated industry to follow them is standard procedure, but this is a passive approach to solving environmental problems. The goal of the company thereafter was to take a leadership, proactive role and guide the MAF contamination clean up to its best conclusion at minimum time and lowest cost to NASA. To accomplish this goal, we have established a positive working relationship with LDEQ, involving them interactively in the implementation of advanced remedial activities at MAF as outlined in the following paragraphs.
NASA Ames Research Center is responsible for the development of the Space Station Biological Research Project (SSBRP) which will support non-human life sciences research on the International Space Station Alpha (ISSA). The SSBRP is designed to support both basic research to understand the effect of altered gravity fields on biological systems and applied research to investigate the effects of space flight on biological systems. The SSBRP will provide the necessary habitats to support avian and reptile eggs, cells and tissues, plants and rodents. In addition a habitat to support aquatic specimens will be provided by our international partners. Habitats will be mounted in ISSA compatible racks at u-g and will also be mounted on a 2.5 m diameter centrifuge except for the egg incubator which has an internal centrifuge. The 2.5 m centrifuge will provide artificial gravity levels over the range of 0.01 G to 2 G. The current schedule is to launch the first rack in 1999, the Life Sciences glovebox and a second rack early in 2001, a 4 habitat 2.5 in centrifuge later the same year in its own module, and to upgrade the centrifuge to 8 habitats in 2004. The rodent habitats will be derived from the Advanced Animal Habitat currently under development for the Shuttle program and will be capable of housing either rats or mice individually or in groups (6 rats/group and at least 12 mice/group). The egg incubator will be an upgraded Avian Development Facility also developed for the Shuttle program through a Small Business and Innovative Research grant. The Space Tissue Loss cell culture apparatus, developed by Walter Reed Army Institute of Research, is being considered for the cell and tissue culture habitat. The Life Sciences Glovebox is crucial to all life sciences experiments for specimen manipulation and performance of science procedures. It will provide two levels of containment between the work volume and the crew through the use of seals and negative pressure. The glovebox will accommodate use by two crew persons simultaneously and the capability for real time video down-link and data acquisition. In house testbeds and Phase B studies of the centrifuge validated the concepts of vibration isolation and autobalancing systems to meet the ISSA microgravity requirements. The vibration isolation system is effective above the centrifuge rotation frequency while the autobalancing system on the rotor removes vibration at and below the rotation rate. Torque of the Station, induced by spin-up/spindown of the centrifuge, can be minimized by controlling spin-up/spin-down rates. The SSBRP and ISSA will provide the opportunity to perform long-term, repeatable and high quality science. The long duration increments available on the Station will permit multigeneration studies of both plants and animals which have not previously been possible. The u-g habitat racks and the eight habitat centrifuge will accommodate sufficient number of specimens to permit statistically significant sampling of specimens to investigate the time course of adaptation to altered gravity environments. The centrifuge will, for the first time, permit investigators to use gravity itself as a tool to investigate fundamental processes, to investigate the intensity and duration of gravity to maintain normal structure and function, to separate the effects of u-g from other environmental factors and to examine artificial gravity as a potential countermeasure for the physical deconditioning observed during space flight.
As part of the continuing effort to identify approaches to improve the safety and reliability of the Space Shuttle system, a Five-Segment Booster (FSB) design was conceptualized as a replacement for the current Space Shuttle boosters. The FSB offers a simple, unique approach to improve astronaut safety and increase performance margin. To determine the feasibility of the FSB, a Phase A study effort was sponsored by NASA and directed by the Marshall Space Flight Center. This study was initiated in March of 1999 and completed in December of 2000. The basic objective of this study was to assess the feasibility of the FSB design concept and also estimate the cost and scope of a full-scale development program for the FSB. In order to ensure an effective and thorough evaluation of the FSB concept, four team members were put on contract to support various areas of importance in assessing the overall feasibility of the design approach.
The Astrobiology Explorer (ABE) is a MIDEX mission concept, currently under Concept Phase A study at NASA's Ames Research Center in collaboration with Ball Aerospace & Technologies, Corp., and managed by NASA's Jet Propulsion Laboratory. ABE will conduct infrared spectroscopic observations to address important problems in astrobiology, astrochemistry, and astrophysics. The core observational program would make fundamental scientific progress in understanding the distribution, identity, and evolution of ices and organic matter in dense molecular clouds, young forming stellar systems, stellar outflows, the general diffuse ISM, HII regions, Solar System bodies, and external galaxies. The ABE instrument concept includes a 0.6 m aperture Ritchey-Chretien telescope and three moderate resolution (R = 2000-3000) spectrometers together covering the 2.5-20 micron spectral region. Large format (1024 x 1024 pixel) IR detector arrays will allow each spectrometer to cover an entire octave of spectral range per exposure without any moving parts. The telescope will be cooled below 50 K by a cryogenic dewar shielded by a sunshade. The detectors will be cooled to approx. 7.5 K by a solid hydrogen cryostat. The optimum orbital configuration for achieving the scientific objectives of the ABE mission is a low background, 1 AU Earth driftaway orbit requiring a Delta II launch vehicle. This configuration provides a low thermal background and allows adequate communications bandwidth and good access to the entire sky over the approx. 1.5 year mission lifetime.
An understanding of the petrogenesis of lunar magmas, particularly mare basalts and the parent magmas to the Mg-rich suite, remains an unfulfilled goal. The fact is not surprising given the complexity of the problem. On the Moon, the source region for lunar magmas is not primitive mantle but rather a series of cumulate rocks that vary widely in both minerology and major and minor element contents. The stratigraphy of the cumulate mantle is not likely to be very regular given that the culumate pile is formed initially in an unstable configuration and subsequent thermal and compositional heterogeneities on a number of length scales. These lithologic heterogeneities, the large range of pressures and temperatures over which melts are generated on the Moon, and the close juxtaposition of cumulate rock with widely varying solidii introduce significant complications to the nature of the melting relations that control melt generation. These factors, coupled with the likelihood that polybaric fractional melting of varying efficiencies ultimately control the composition of planetary progress, are ample reasons why the lunar magmas remain the enigma they are. To make progress, phase equilibria studies must be coupled with a detailed understanding of the time scales and the dynamics of crystal and melt reequilibration processes.
Free-free absorption is an important contribution to the opacity for radiation transport through hot materials Temperatures can be as high as several keV, such that it becomes a computational challenge to solve the Schrodinger equation efficiently for rapidly oscillating continuum functions for high angular momenta. Several groups\footnots, including ours, have studied the phase amplitude solution (PAS) of the Schrodinger equation, in which one solves equations for the wave function amplitude and phase, which are: smooth functions of the electron energy. It is also important to have an accurate Schroudinger benchmark for the development of the PAS method. We present results for dipole matrix elements, Gaunt factors, and cross sections for the absorption of radiation at various energies for Cs XIX at temperature=100 eV and density=0.187 g/cc for our newly developed PAS and Schrodinger benchmark.
The scientific objective of this research is to increase the fundamental knowledge base for liquid- phase processing of technologically important oxide materials. The experimental objective is to define conditions and hardware requirements for microgravity flight experiments to test and expand the experimental hypotheses that: 1. Liquid phase transitions can occur in undercooled melts by a diffusionless process. 2. Onset of the liquid phase transition is accompanied by a large change in the temperature dependence of melt viscosity. Experiments on undercooled YAG (Y3A15012)- and rare earth oxide aluminate composition liquids demonstrated a large departure from an Arrhenian temperature dependence of viscosity. Liquid YAG is nearly inviscid at its 2240 K melting point. Glass fibers were pulled from melts undercooled by ca. 600 K indicating that the viscosity is on the order of 100 Pans (1000 Poise) at 1600 K. This value of viscosity is 500 times greater than that obtained by extrapolation of data for temperatures above the melting point of YAG. These results show that the liquids are extremely fragile and that the onset of the highly non-Arrhenian viscosity-temperature relationship occurs at a temperature considerably below the equilibrium melting point of the solid phases. Further results on undercooled alumina-yttria melts containing 23-42 mole % yttrium oxide indicate that a congruent liquid-liquid phase transition occurs in the undercooled liquids. The rates of transition are inconsistent with a diffusion-limited process. This research is directed to investigation of the scientifically interesting phenomena of polyamorphism and fragility in undercooled rare earth oxide aluminum oxide liquids. The results bear on the technologically important problem of producing high value rare earth-based optical materials.
The issue of whether martian magmas are wet or dry is an important one. The answer to this basic question has profound consequences for how we think about Mars as a planet. Recently, several lines of evidence have been presented that collectively suggest that shergottite parent magmas were once wet. These include: (i) phase equilibria studies that indicate that the Shergotty parent magma required ~2 wt.% water in order to be co-saturated with both pigeonite and augite, (ii) reverse zoning of light lithophile elements (Li and B) in shergottite pyroxenes, suggesting the exsolution and removal of an aqueous fluid, and (iii) measurement of D/H ratios in SNC minerals that are much lower than atmospheric, suggesting that there may be juvenile (primordial) mantle water. Below I will review the evidence for the diametrically opposite case, that shergottite magmas were effectively dry (<< 1 wt.% H 2 O).
An amitochondriate trichomonad cell of the family Devescovinidae (Class Parabasalia), helped demonstrate the fluid model of lipoprotein cell membranes. This wood-ingesting symbiont in the hindgut of the dry wood-eating termite Cryptotermes cavifrons is informally known to cell biologists as "Rubberneckia". As the microtubular axo-style complex generates force causing clockwise movement of the entire anterior portion of the cell at the shear zone the protist displays "head" rotation. Studies by phase contrast and videomicroscopy of live cells, of whole mounts by scanning, and thin sections by transmission electron microscopy extend the observations of Tamm and Tamm [24-26] and Tamm [19-23]. Habitat, cell shape, size, nuclear features, parabasal apparatus and other morphological details permit the assignment of "Rubberneckia" to Kirby's cosmopolitan genus Caduceia. This large-sized devescovinid has distinctive parabasal gyres, an axostylar rotary, motor, and regularly-associated nonflagellated, fusiform and flagellated rod epibiotic surface bacteria. In addition to regularly aligned epibionts intranuclear and endocytoplasmic bacteria are abundant and hydrogenosomes are Present. "Rubberneckia" is compared here to the other seven species of Caduceia. Since it is clearly sufficiently distinctive to warrant new species status, we named it C. versatilis.
The physical state of food components affects their properties during processing, storage, and consumption. Removal of water by evaporation or by freezing often results in formation of an amorphous state (Parks et al., 1928; Troy and Sharp, 1930; Kauzmann, 1948; Bushill et al., 1965; White and Cakebread, 1966; Slade and Levine, 1991). Amorphous foods are also produced from carbohydrate melts by rapid cooling after extrusion or in the manufacturing of hard sugar candies and coatings (Herrington and Branfield, 1984). Formation of the amorphous state and its relation to equilibrium conditions are shown in Fig. 1 [see text]. The most important change, characteristic of the amorphous state, is noticed at the glass transition temperature (Tg), which involves transition from a solid "glassy" to a liquid-like "rubbery" state. The main consequence of glass transition is an increase of molecular mobility and free volume above Tg, which may result in physical and physico-chemical deteriorative changes (White and Cakebread, 1966; Slade and Levine, 1991). We have conducted studies on phase transitions of amorphous food materials and related Tg to composition, viscosity, stickiness, collapse, recrystallization, and ice formation. We have also proposed that some diffusion-limited deteriorative reactions are controlled by the physical state in the vicinity of Tg (Roos and Karel, 1990, 1991a, b, c). The results are summarized in this article, with state diagrams based on experimental and calculated data to characterize the relevant water content, temperature, and time-dependent phenomena of amorphous food components.
This work gives an algorithm for computing the degrees of freedom of estimators of Allan and Hadamard variances, including their modified versions. A consistent approach is used throughout.
No abstract available