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At least 793 records · Page 44

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NASA NTRS1997

Advanced Film Cooling Rig: Development and Test Results

The Advanced Film Cooling Rig (AFCR) test was a program to develop a thermal imaging camera system to measure the effectiveness of multihole film cooling. This system was used to evaluate low-thermal conductivity ceramic test panels incorporating a wide range of multihole cooling geometries. Tests were conducted with a mainstream flow of 600 F at Mach numbers of 0.37 and 1.57. Coolant flow was controlled to give a blowing parameter variation of up to 2.9. Data reduction techniques are given for camera calibration, rig temperature reflection correction, and deriving surface temperatures from video images. Results are presented in terms of overall and film cooling effectiveness distributions. A one-dimensional analysis of a unit film cooling hole was performed to generate film temperature.

Reilly, R. S.↗

NASA NTRS2004

Contribution of TOMS to Earth Science- An Overview

The TOMS instrument was launched on the Nimbus-7 satellite in Oct 1978 with the goal of understanding the meteorological influences on the ozone column. The nominal lifetime of the instrument was 1 year. However, in response to the concern over possible man-made influences on the ozone layer NASA continued to nurse the instrument for 13.5 years and launched a major program to produce accurate trend quality dataset of ozone. Despite severe optical degradation and other significant anomalies that developed in the instrument over its lifetime, the effort turned out to be a tremendous success. In 1984, TOMS took center stage as the primary provider of Antarctic ozone hole maps to the world community; it continues to play that role until today. An unexpected benefit of the close attention paid to improving the TOMS data quality was that several atmospheric constituents that interfere with ozone measurement were also identified and meticulously converted into long-term datasets of their own. These constituents include clouds, volcanic S02, aerosols, and ocean phytoplankton. In addition, the high quality of the basic datasets made it possible to produce global maps of surface UV and tropospheric ozone. In most cases there are no other sources of these data sets. Advanced UV instruments currently under development in the US and Europe will continue to exploit the TOMS-developed techniques for several decades.

Bhartia, P. K.↗

NASA NTRS2002

STARDUST and Interplanetary Dust Particles - Big Science from Small Samples

Comets are primitive bodies that are widely believed to be a reservoir of preserved interstellar and circumstellar grains, and molecular cloud materials (organics). Direct samples of cometary dust along with interstellar grains will be returned by the STARDUST Mission in 2006. Analyses of interplanetary dust particles (IDPs) and analogue materials in the laboratory provide constraints and serve as "ground truth" for evaluating various hypotheses on the nature of comets and interstellar grains. Anhydrous IDPs are the most primitive remnants of the primordial Solar System, and are our only known samples of comets. These cometary lDPs are rich in preserved interstellar organic compounds II]. In addition, abundant interstellar silicates have recently been discovered in cluster lDPs [2]. In some of these IDPs, the presolar silicate abundance reaches 1 wt %, exceeding the total presolar grain abundance in meteorites by three orders of magnitude, where presolar silicates are still notably absent. The results to date support the idea that comets are rich in presolar materials, but are at odds with the common perception that they are 'pristine aggregates of interstellar grains'. These results underscore the scientific importance of sample return missions to comets. The technology for the analysis of micrometer-sized samples is well advanced. The newest generation of ion probe instruments allow for isotopic analyses at the submicrometer level. The nature of the organic matter is analyzed using Infrared and soft X-ray spectroscopy techniques on synchrotron-based instruments, also at the micrometer-scale and smaller. Electron microscopy and spectroscopy provide details on the mineralogy and chemistry of constituent grains in !DPs at nearly the atomic scale. Novel sample preparation techniques have been developed such that all of these measurements can now be made on the same 10 micrometer diameter particle. Returned comet samples captured in aerogel will pose new challenges in sample analysis, but should provide a major leap in our understanding of the fundamental building blocks of our Solar System.

Keller, L. P.↗

NASA NTRS1990

Feasibility study for the advanced one-dimensional high temperature optical strain measurement system, phase 3

The Instrumentation and Control Technology Division is developing optical strain measurement systems for applications using high temperature wire and fiber specimens. This feasibility study has determined that stable optical signals can be obtained from specimens at temperatures beyond 2,400 C. A system using an area array sensor is proposed to alleviate off-axis decorrelation arising from rigid body motions. A digital signal processor (DSP) is recommended to perform speckle correlations at a rate near the data acquisition rate. Design parameters are discussed, and fundamental limits on the speckle shift strain measurement technique are defined.

Lant, Christian T.↗

NASA NTRS1983

The GSFC Advanced Compton Telescope (ACT)

A new telescope is being developed at GSFC for the study of point sources of gamma rays in the energy range 1-30 MeV. Using the detection principle of a Compton scatter in a 2.5 cm thick NaI(Tl) detector followed by absorption in a 15 cm thick NaI(Tl) detector, the telescope uses a rocking collimator for field-of-view reduction and background subtraction. Background reduction techniques include lead-plastic scintillator shielding, pulse shape discrimination and Anger camera operation to both NaI detectors, as well as a time-of-flight measurement between them. The instrument configuration and status is described.

Hartman, R.↗

NASA NTRS1992

Advanced one-dimensional optical strain measurement system, phase 4

An improved version of the speckle-shift strain measurement system was developed. The system uses a two-dimensional sensor array to maintain speckle correlation in the presence of large off-axis rigid body motions. A digital signal processor (DSP) is used to calculate strains at a rate near the RS-170 camera frame rate. Strain measurements were demonstrated on small diameter wires and fibers used in composite materials research. Accurate values of Young's modulus were measured on tungsten wires, and silicon carbide and sapphire fibers. This optical technique has measured surface strains at specimen temperatures above 750 C and has shown the potential for measurements at much higher temperatures.

Lant, Christian T.↗

NASA NTRS2017

Update on Risk Reduction Activities for a Liquid Advanced Booster for NASA's Space Launch System

The stated goals of NASA's Research Announcement for the Space Launch System (SLS) Advanced Booster Engineering Demonstration and/or Risk Reduction (ABEDRR) are to reduce risks leading to an affordable Advanced Booster that meets the evolved capabilities of SLS and enable competition by mitigating targeted Advanced Booster risks to enhance SLS affordability. Dynetics, Inc. and Aerojet Rocketdyne (AR) formed a team to offer a wide-ranging set of risk reduction activities and full-scale, system-level demonstrations that support NASA's ABEDRR goals. During the ABEDRR effort, the Dynetics Team has modified flight-proven Apollo-Saturn F-1 engine components and subsystems to improve affordability and reliability (e.g., reduce parts counts, touch labor, or use lower cost manufacturing processes and materials). The team has built hardware to validate production costs and completed tests to demonstrate it can meet performance requirements. State-of-the-art manufacturing and processing techniques have been applied to the heritage F-1, resulting in a low recurring cost engine while retaining the benefits of Apollo-era experience. NASA test facilities have been used to perform low-cost risk-reduction engine testing. In early 2014, NASA and the Dynetics Team agreed to move additional large liquid oxygen/kerosene engine work under Dynetics' ABEDRR contract. Also led by AR, the objectives of this work are to demonstrate combustion stability and measure performance of a 500,000 lbf class Oxidizer-Rich Staged Combustion (ORSC) cycle main injector. A trade study was completed to investigate the feasibility, cost effectiveness, and technical maturity of a domestically-produced engine that could potentially both replace the RD-180 on Atlas V and satisfy NASA SLS payload-to-orbit requirements via an advanced booster application. Engine physical dimensions and performance parameters resulting from this study provide the system level requirements for the ORSC risk reduction test article. The test article is scheduled to complete fabrication and assembly soon and continue testing through late 2019. Dynetics has also designed, developed, and built innovative tank and structure assemblies using friction stir welding to leverage recent NASA investments in manufacturing tools, facilities, and processes, significantly reducing development and recurring costs. The full-scale cryotank assembly was used to verify the structural design and prove affordable processes. Dynetics performed hydrostatic and cryothermal proof tests on the assembly to verify the assembly meets performance requirements..

Crocker, Andrew M.↗

NASA NTRS1972

Advanced dosimetry systems for the space transport and space station

Advanced dosimetry system concepts are described that will provide automated and instantaneous measurement of dose and particle spectra. Systems are proposed for measuring dose rate from cosmic radiation background to greater than 3600 rads/hr. Charged particle spectrometers, both internal and external to the spacecraft, are described for determining mixed field energy spectra and particle fluxes for both real time onboard and ground-based computer evaluation of the radiation hazard. Automated passive dosimetry systems consisting of thermoluminescent dosimeters and activation techniques are proposed for recording the dose levels for twelve or more crew members. This system will allow automatic onboard readout and data storage of the accumulated dose and can be transmitted to ground after readout or data records recovered with each crew rotation.

Wailly, L. F.↗

NASA NTRS1982

A study of aerodynamic heating distributions on a tip-fin controller installed on a Space Shuttle Orbiter model

The aerodynamic heating of a tip-fin controller mounted on a Space Shuttle Orbiter model was studied experimentally in the Calspan Advanced Technology Center 96 inch Hypersonic Shock Tunnel. A 0.0175 scale model was tested at Mach numbers from 10 to 17.5 at angles of attack typical of a shuttle entry. The study was conducted in two phases. In phase 1 testing a thermographic phosphor technique was used to qualitatively determine the areas of high heat-transfer rates. Based on the results of this phase, the model was instrumented with 40 thin-film resistance thermometers to obtain quantitative measurements of the aerodynamic heating. The results of the phase 2 testing indicate that the highest heating rates, which occur on the leading edge of the tip-fin controller, are very sensitive to angle of attack for alpha or = 30 deg. The shock wave from the leading edge of the orbiter wing impinges on the leading edge of the tip-fin controller resulting in peak values of h/h(Ref) in the range from 1.5 to 2.0. Away from the leading edge, the heat-transfer rates never exceed h/h(Ref) = 0.25 when the control surface, is not deflected. With the control surface deflected 20 deg, the heat-transfer rates had a maximum value of h/h(Ref) = 0.3. The heating rates are quite nonuniform over the outboard surface and are sensitive to angle of attack.

Wittliff, C. E.↗

NASA NTRS1989

An Approximate Model for the Performance and Acoustic Predictions of Counterrotating Propeller Configurations

An approximate method was developed to analyze and predict the acoustics of a counterrotating propeller configuration. The method employs the analytical techniques of Lock and Theodorsen as described by Davidson to predict the steady performance of a counterrotating configuration. Then, a modification of the method of Lesieutre is used to predict the unsteady forces on the blades. Finally, the steady and unsteady loads are used in the numerical method of Succi to predict the unsteady acoustics of the propeller. The numerical results are compared with experimental acoustic measurements of a counterrotating propeller configuration by Gazzaniga operating under several combinations of advance ratio, blade pitch, and number of blades. In addition, a constant-speed commuter-class propeller configuration was designed with the Davidson method and the acoustics analyzed at three advance ratios. Noise levels and frequency spectra were calculated at a number of locations around the configuration. The directivity patterns of the harmonics in both the horizontal and vertical planes were examined, with the conclusion that the noise levels of the even harmonics are relatively independent of direction whereas the noise levels of the odd harmonics are extremely dependent on azimuthal direction in the horizontal plane. The equations of Succi are examined to explain this behavior.

Denner, Brett William↗

NASA NTRS1996

Medical and surgical applications of space biosensor technology

Researchers in space life sciences are rapidly approaching a technology impasse. Many of the critical questions on the impact of spaceflight on living systems simply cannot be answered with the limited available technologies. Research subjects, particularly small animal models like the rat, must be allowed to function relatively untended and unrestrained for long periods to fully reflect the impact of microgravity and spaceflight on their behavior and physiology. These requirements preclude the use of present hard-wired instrumentation techniques and limited data acquisition systems. Implantable sensors and miniaturized biotelemetry are the only means of capturing the fundamental and critical data. This same biosensor and biotelemetry technology has direct application to Earth-based medicine and surgery. Continuous, on-line data acquisition and improved measurement capabilities combined with the ease and flexibility offered by automated, wireless, and portable instruments and data systems, should provide a boon to the health care industry. Playing a key role in this technology revolution is the Sensors 2000! (S2K!) Program at NASA Ames Research Center. S2K!, in collaboration with space life sciences researchers and managers, provides an integrated capability for sensor technology development and applications, including advanced biosensor technology development, spaceflight hardware development, and technology transfer and commercialization. S2K! is presently collaborating on several spaceflight projects with dual-use medical applications. One prime example is a collaboration with the Fetal Treatment Center (FTC) at the University of California at San Francisco. The goal is to develop and apply implantable chemical sensor and biotelemetry technology to continuously monitor fetal patients during extra-uterine surgery, replacement into the womb, through birth and beyond. Once validated for ground use, the method will be transitioned to spaceflight applications to remotely monitor key biochemical parameters in flight animals. Successful application of NASA implantable biosensor and biotelemetry technologies should accelerate the advancement of this and other modern medical procedures while furthering the exploration of life in space.

NASA Discipline General Space Life Sciences↗

NASA NTRS1993

Develop advanced nonlinear signal analysis topographical mapping system

As reported in the monthly technical progress report for July 1993, a new signal analysis technique called instantaneous frequency correlation (IFC) for time delay estimation was developed which will be incorporated into the ATMS system. In this report, a different technique for time delay estimation called phase difference time derivative estimator (FDTDE) will be discussed. The FDTDE technique does not replace the IFC method since their application conditions are different. The IFC technique can estimate the time delay between two spectral components of two measurement signals when the center frequency of the components is constant, while the FDTDE method can provide accurate time delay estimation when the frequency of the subject component changes linearly such as during engine startup or shut-down.

Jong, Jen-Yi↗

NASA NTRS1975

Recent advances in the applications of pulsed lasers in the hydrosphere

Laboratory and field measurements have been performed on the transmission/scattering characteristics of a pulsed neon laser as a function of water turbidity. These results have been used to establish the criteria for an airborne laser bathymetry system. Extensive measurements have been made of laser induced fluorescence using a pulsed tunable dye laser. Feasibility has been demonstrated for remote detection and possible identification of various types of algae and oils. Similar measurements made on a wide variety of organic dyes have shown this technique to have applications in remote measurements of subsurface currents, temperature and salinity.

Hickman, G. D.↗

NASA NTRS1959

Global Aspects of the Exploration of Space

The interest of man in outer space began long ago among uncivilized peoples to whom the face of the sky was clock and almanac; the celestial bodies, objects of worship. Exploration was at first by visual observation, later aided by armillary spheres and quadrants, and still later by more precise measuring instruments, telescopes, and spectroscopes. The information obtained was that borne by the light that was transmitted from the distant celestial object through the atmosphere to the observing instrument on the ground. In recent years the light waves have been supplemented by radio waves as carriers of information from the stars and planets. Men of many nations have contributed through the centuries to the exploration of space by the methods of astronomy. The history of advances in astronomical knowledge and technique includes the records of Chinese, Babylonians, Greeks, Arabians, and of nearly every nation of the modern world. International cooperation was early recognized as essential and beneficial; the countless number of the stars and the vastness of space present mankind with a truly global task. The picture of the universe obtained by the astronomers early stirred the imagination of men to speculate about the existence of life elsewhere in the universe, about means of communication with distant stars, and in the last centuries about the possibility of the travel of man to the moon and planets. Some sought to apply the science and engineering of their day to describe the vehicles to be used. For example, Jules Verne published in 1865 in "From the Earth to the Moon" a description of a gun-launched projectile carrying passengers to orbit the moon. Today we have taken the first steps to bring this inspired vision to reality. The exploration of space by unmanned vehicles carrying scientific apparatus began on October 4, 1957; exploration by man will follow in due course.

Dryden, Hugh L.↗

NASA NTRS1974

Airline return-on-investment model for technology evaluation

This report presents the derivation, description, and operating instructions for a computer program (TEKVAL) which measures the economic value of advanced technology features applied to long range commercial passenger aircraft. The program consists of three modules; and airplane sizing routine, a direct operating cost routine, and an airline return-on-investment routine. These modules are linked such that they may be operated sequentially or individually, with one routine generating the input for the next or with the option of externally specifying the input for either of the economic routines. A very simple airplane sizing technique was previously developed, based on the Brequet range equation. For this program, that sizing technique has been greatly expanded and combined with the formerly separate DOC and ROI programs to produce TEKVAL.

Source record↗

NASA NTRS1982

Advanced multispectral remote sensing technology and applications; Proceedings of the Conference, Arlington, VA, May 6, 7, 1982

Sensor system concepts are discussed, taking into account a multispectral linear array instrument design, an improved earth resources sensing instrument, design tradeoffs for a multispectral linear array instrument, imaging spectrometer technologies for advanced earth remote sensing, and the design concept for an optimized earth radiation budget sensor. Topics related to supporting optics and signal processing methodologies are explored, giving attention to two mirror objective design for multispectral remote sensing, the measurement of optical modulation functions in sparsely sampled mosaic focal plane arrays, multispectral linear array focal plane signal processing, signal processing for the NASA multispectral linear array, the concept for a multiple resolution pushbroom sensor, and the evolution of the octal radiometer. Techniques and applications for multispectral data are considered along with aspects of focal plane technology.

Ando, K. J.↗

NASA NTRS1996

A Method for Characterizing Thermoset Polyimides

Thermoset polyimides have great potential for successfully meeting tough stress and temperature challenges in the advanced aircraft development program. However, studies of structure-property relationships in these materials have not been very successful so far. Positron lifetime spectroscopy (PLS) has been used to investigate free volumes and associated parameters in a series of variable, segmental molecular weight samples. The free volume correlates well with the molecular weight M(sub c), the cross-link density v, and the coefficient of thermal expansion (CTE) of these materials. Currently, no other techniques are available for direct measurement of these parameters, particularly for polymers in solid phase. Experimental results and their interpretations are presented.

Ranganathaiah, C.↗

NASA NTRS2000

Thermal Conductivity Change Kinetics of Ceramic Thermal Barrier Coatings Determined by the Steady-State Laser Heat Flux Technique

A steady-state laser heat flux technique has been developed at the NASA Glenn Research Center at Lewis Field to obtain critical thermal conductivity data of ceramic thermal barrier coatings under the temperature and thermal gradients that are realistically expected to be encountered in advanced engine systems. In this study, thermal conductivity change kinetics of a plasma-sprayed, 254-mm-thick ZrO2-8 wt % Y2O3 ceramic coating were obtained at high temperatures. During the testing, the temperature gradients across the coating system were carefully measured by the surface and back pyrometers and an embedded miniature thermocouple in the substrate. The actual heat flux passing through the coating system was determined from the metal substrate temperature drop (measured by the embedded miniature thermocouple and the back pyrometer) combined with one-dimensional heat transfer models.

Zhu, Dongming↗