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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 1,639 records · Page 91

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NASA NTRS1987

Second generation experiments in fault tolerant software

The purpose of the Multi-Version Software (MVS) experiment is to obtain empirical measurements of the performance of multi-version systems. Twenty version of a program were prepared under reasonably realistic development conditions from the same specifications. The overall structure of the testing environment for the MVS experiment and its status are described. A preliminary version of the control system is described that was implemented for the MVS experiment to allow the experimenter to have control over the details of the testing. The results of an empirical study of error detection using self checks are also presented. The analysis of the checks revealed that there are great differences in the ability of individual programmers to design effective checks.

Knight, J. C.↗

NASA NTRS1985

Multiwall/RSI concept for local application to space shuttle body flap

A titanium multiwall/reusable surface insulation (MW/RSI) TPS concept designed to prevent local erosion of the RSI tiles on the upper surface of the Space Shuttle Orbiter body flap was investigated. The concept, which consisted of a combination of a titanium multiwall tile and an RSI tile, was evaluated by thermal analysis and structural and thermal testing of one configuration to assess the attachment scheme and thermal behavior. Results indicate that the MW/RSI concept will remain attached to the vehicle and provide the required thermal protection.

Shideler, John L.↗

NASA NTRS1987

A Vibroacoustic Database Management Center for Shuttle and expendable launch vehicle payloads

A Vibroacoustic Database Management Center has recently been established at the Jet Propulsion Laboratory (JPL). The center uses the Vibroacoustic Payload Environment Prediction System (VAPEPS) computer program to maintain a database of flight and ground-test data and structural parameters for both Shuttle and expendable launch-vehicle payloads. Given the launch-vehicle environment, the VAPEPS prediction software, which employs Statistical Energy Analysis (SEA) methods, can be used with or without the database to establish the vibroacoustic environment for new payload components. This paper summarizes the VAPEPS program and describes the functions of the Database Management Center at JPL.

Thomas, Valerie C.↗

NASA NTRS1988

Globular cluster luminosity functions

The use of luminosity functions in determining the helium content, age, and initial mass function of globular clusters, and in testing the stellar structure theory is reviewed. The main sequence turnoff and subgiant phases are examined. The Thomas (1967) peak in the luminosity function and the gap near the base of the giant branch of globular clusters found in the CM are discussed as probes of stellar structure. Research in the area of faint star photometry, dealing with the lower main sequence luminosity function and the interplanetary magnetic field is presented.

Demarque, Pierre↗

NASA NTRS1988

The effects of leading edge and downstream film cooling on turbine vane heat transfer

The progress under contract NAS3-24619 toward the goal of establishing a relevant data base for use in improving the predictive design capabilities for external heat transfer to turbine vanes, including the effect of downstream film cooling with and without leading edge showerhead film cooling. Experimental measurements were made in a two-dimensional cascade previously used to obtain vane surface heat transfer distributions on nonfilm cooled airfoils under contract NAS3-22761 and leading edge showerhead film cooled airfoils under contract NAS3-23695. The principal independent parameters (Mach number, Reynolds number, turbulence, wall-to-gas temperature ratio, coolant-to-gas temperature ratio, and coolant-to-gas pressure ratio) were maintained over ranges consistent with actual engine conditions and the test matrix was structured to provide an assessment of the independent influence of parameters of interest, namely, exit Mach number, exit Reynolds number, coolant-to-gas temperature ratio, and coolant-to-gas pressure ratio. Data provide a data base for downstream film cooled turbine vanes and extends the data bases generated in the two previous studies. The vane external heat transfer obtained indicate that considerable cooling benefits can be achieved by utilizing downstream film cooling. The data obtained and presented illustrate the interaction of the variables and should provide the airfoil designer and computational analyst the information required to improve heat transfer design capabilities for film cooled turbine airfoils.

Hylton, L. D.↗

NASA NTRS1989

Carousel deployment mechanism for coilable lattice truss

The development of a mechanism for instrumentation and solar-array deployment is discussed. One part of the technology consists of a smart motor which can operate in either an analog mode to provide high speed and torque, or in the stepper mode to provide accurate positioning. The second technology consists of a coilable lattice mast which is deployed and rotated about its axis with a common drive system. A review of the design and function of the system is presented. Structural and thermal test data are included.

Warden, Robert M.↗

NASA NTRS1990

Simulating A Massive, Mobile Structure

Simulator replicates, kinematically and dynamically, mating of large, massive mobile structure with similarly large and massive fixed structure. Developed for testing berthing-and-latching mechanism. Fixed section holds active berthing-and-latching mechanism and its motor control system with optical encoder to maintain synchronization among four latches in mechanism. Tripodal load-cell network gathers data on load history of berthing operation, and infrared tracking system including light-emitting diodes produces data for position history.

Fantasia, Peter M.↗

NASA NTRS1989

An experimental study of turbine vane heat transfer with leading edge and downstream film cooling

This paper presents the effects of downstream film cooling, with and without leading edge showerhead film cooling, on turbine-vane external heat transfer. Steady-state experimental measurements were made in a three-vane linear two-dimensional cascade. The principal independent parameters were maintained over ranges consistent with actual engine conditions. The test matrix was structured to provide an assessment of the independent influence of parameters of interest, namely, exit Mach number, exit Reynolds number, coolant-to-gas temperature ratio, and coolant-to-gas pressure ratio. The data obtained indicate that considerable cooling benefits can be achieved by utilizing downstream film cooling. The downstream film cooling process was shown to be a complex interaction of two competing mechanisms. The thermal dilution effect, associated with the injection of relatively cold fluid, results in a decrease in the heat transfer to the airfoil. Conversely, the turbulence augmentation, produced by the injection process, results in increased heat transfer to the airfoil.

Nirmalan, V.↗

NASA NTRS1992

Ultrasonic Dynamic Vector Stress Sensor

Stress inferred from measurements in specimens rather than in bonded gauges. Ultrasonic dynamic vector stress sensor (UDVSS) measures changes in dynamic directional stress occurring in material or structure at location touched by device when material or structure put under cyclic load. Includes phase-locked loop, synchronous amplifier, and contact probe. Useful among manufacturers of aerospace and automotive structures for stress testing and evaluation of designs.

Heyman, Joseph S.↗

NASA NTRS1991

Status of Japanese Experiment Module (JEM) activities

The current status of the JEM activities are presented in graphic form. The JEM spacecraft configuration is presented. The JEM configuration consist of the Pressurized Module, the Exposed Facility, the Experiment Logistics Module which consist of a pressurized section and an exposed section; and the Remote Manipulator System. The master schedule of the space station is given. Also the development tests of the structure and mechanism, the electrical power system, the data management system, the thermal control system, the environment control system, the experiment support system, and the remote manipulator system are listed.

Source record↗

NASA NTRS1991

A review of Space Shuttle payload-bay lift-off flight data and analysis comparisons

The design evolution of Space Shuttle payloads to be launched requires structural analyses and testing, based on Shuttle load environments, to ensure flight safety and mission success. The adequacy of predicted load environments is continually assessed against flight and ground measured data. The Space Shuttle program has utilized extensive flight measurements to assess payload bay environments. As part of the orbital flight test program on STS-1 through STS-5, the orbiter Columbia was equipped with a broad range of instrumentation, including accelerometers and microphone in the payload bay. The orbiter Challenger was equipped with payload bay measurement systems on six of its flights, and the orbiter Discovery was similarly instrumented beginning with STS-26. The payload bay data, along with other measurements recorded on these flights, are compared to design load requirements for payloads, and updates are made as necessary.

Hamilton, David A.↗

NASA NTRS1991

Dynamics and control of the Space Station Freedom docking/array feathering maneuver

Analysis performed at Lewis Research Center has indicated that it is possible to fail a photovoltaic array of the Space Station Freedom during a Shuttle approach, due to impingements by Shuttle attitude jet firing plumes. A solution to this potential problem is the feathering of the arrays. This study deals with fine adjustments in feathered position for extra plume load relief. A mathematical model for fine feathering is described. The Shuttle is treated as a single rigid body, with prescribed jet firings. Freedom is treated as a system of rigid bodies, with high-fidelity gimbal dynamics. Uncertainty is found in disturbances, plume dynamic pressure, gimbal friction and misalignments. Assumptions, model structure and analysis test plan are presented.

Graham, Ronald E.↗

NASA NTRS1992

Experimental study of plate buckling induced by spatial temperature gradients

An experimental study of plate buckling induced by spatial temperature gradients is described. A rectangular Hastelloy-X panel is subjected to local line heating by a focused quartz heat lamp. Two parallel panel edges are maintained at constant temperature by coolant flow. Point supports provide well-defined thermal-structural boundary conditions. Test results from transient elastic and inelastic tests demonstrate that substantial panel bending occurs due to initial panel warpage and thermally induced membrane compressive stresses.

Thornton, Earl A.↗

NASA NTRS1992

Active cooling from the sixties to NASP

Vehicles, such as the X-15 or National Aero-Space Plane, traveling at hypersonic speeds through the earth's atmosphere experience aerodynamic heating. The heating can be severe enough that a thermal protection system is required to limit the temperature of the vehicle structure. Although several categories of thermal protection systems are mentioned briefly, the majority of this paper describes convectively cooled structures for large areas. Convective cooling is a method of limiting structural temperatures by circulating a coolant through the vehicle structure. Efforts to develop convectively cooled structures during the past 30 years--from early engine structures, which were intended to be tested on the X-15, to structural--are described. Many of the lessons learned from these research efforts are presented.

Kelly, H. Neale↗

NASA NTRS1992

Csi-star: a Low-cost CSI Orbital Testbed

The topics are presented in viewgraph form and include the following: rationale for an on-orbit control-structurs interaction (CSI) test facility; CSI flight experiment objectives; feasibility study objectives; CSI free-flyer solution; feasibility study technical status summary; CSI-Star - a low-cost CSI free flyer; conceptual experiment design - option 2 configuration; Delta 2 - Quickstar Interface clambband capability; open and closed loop response of baselined truss with active struts; experiment weight baseline (option 1) configuration; experiment weight option 2 configuration; experiment power baseline (option 1) configuration; experiment power option 2 configuration; CSI Quickstar capabilities/requirements; and remaining work.

Edberg, D.↗

NASA NTRS1992

Design and development of a two-phase reservoir for the Capillary Pumped Loop (CAPL) Flight Experiment

The Capillary Pumped Loop (CAPL) Flight Experiment has undergone numerous design modifications to reflect recent changes in the thermal control system baselined for Earth Observation System (EOS) spacecraft. The experiment redesign has also allowed technological advances in two-phase fluid loop components to be incorporated. The experiment's reservoir is one of the components targeted for redesign. The design and development of a new reservoir for the CAPL Flight Experiment is discussed in this paper. A prototype reservoir is described, and a hydrodynamic analysis of its wick structure is included. Testing of the prototype reservoir is also discussed.

Wolf, David A.↗

NASA NTRS1992

Experimental, physical and numerical modeling of lunar regolith and lunar regolith structures

An extensive series of laboratory strength and deformation experiments have been performed on a lunar regolith simulant. Results of these experiments are compared to results from experiments on real lunar regolith from the Apollo and Luna missions to illustrate the suitability of this material in capturing the engineering properties lunar regolith. In addition, these results are used to calibrate a constitutive model used to describe its stress-strain behavior. This model, in conjunction with numerical analysis techniques, is used to predict the response i.e. material parameters) of lunar simulant under 1/6-g and low confining stress conditions. These tools are also used to predict the displacement response of a lunar soil embankment structure used to cover a first generation human habitat module, which might be used to accommodate the first astronauts revisiting the moon. These predictions are compared to physical models of this structure, which are tested in a geotechnical centrifuge in order to satisfy scaling relationships between prototype and model.

Perkins, Steven W.↗

NASA NTRS1993

Reliability Technology to Achieve Insertion of Advanced Packaging (RELTECH) program

A joint military-commercial effort to evaluate multichip module (MCM) structures is discussed. The program, Reliability Technology to Achieve Insertion of Advanced Packaging (RELTECH), has been designed to identify the failure mechanisms that are possible in MCM structures. The RELTECH test vehicles, technical assessment task, product evaluation plan, reliability modeling task, accelerated and environmental testing, and post-test physical analysis and failure analysis are described. The information obtained through RELTECH can be used to address standardization issues, through development of cost effective qualification and appropriate screening criteria, for inclusion into a commercial specification and the MIL-H-38534 general specification for hybrid microcircuits.

Fayette, Daniel F.↗