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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 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1949

Heat Transfer from High-Temperature Surfaces to Fluids. III - Correlation of Heat-Transfer Data for Air Flowing in Silicon Carbide Tube with Rounded Entrance, Inside Diameter of 3/4 Inch, and Effective Length of 12 Inches: Correlation of Heat-Transfer Data for Air Flowing in Silicon Carbide Tube with Rounded Entrance, Inside Diameter of 3/4 Inch, and Effective Length of 12 Inches - Part 3

A heat-transfer investigation was conducted with air flowing through an electrically heated silicon carbide tube with a rounded entrance, an inside diameter of 3/4 inch, and an effective heat-transfer length of 12 inches over a range of Reynolds numbers up to 300,000 and a range of average inside-tube-wall temperature up to 2500 R. The highest corresponding local outside-tube-wall temperature was 3010 R. Correlation of the heat-transfer data using the conventional Nueselt relation wherein physical properties of the fluid were evaluated at average bulk temperature resulted in a separation of data with tube-wall-temperature level. A satisfactory correlation of the heat-transfer data was obtained, however, by the use of modified correlation parameters wherein the mass velocity G (or product of average air density and velocity evaluated at bulk temperature P(sub b)V(sub b)) in the Reynolds number was replaced by the product of average air velocity evaluated at the bulk temperature and density evaluated at either the average inside-tube-wall temperature or the average film temperature; in addition, all the physical properties of air were correspondingly evaluated at either the average inside-tube-wall temperature or the average film temperature.

Sams, Eldon W.↗
NASA NTRS1979

Bounds on the minimum number of data transfers in WFTA and FFT programs

Bounds on the minimum number of data transfers (i.e., loads, stores, copies) required by WFTA and FFT programs are presented. The analysis is applicable to those general-purpose computers with M general processor registers, where M is equal to or greater than 4 but much less than the transform length. It is shown that the 1008-point WFTA requires about 21 percent more data transfers than the 1024-point radix-4 FFT; on the other hand, the 120-point WFTA has about the same number of data transfers as the mixed radix (4 x 4 x 4 x 2) version of the 128-point FFT and 22 percent fewer than the radix-2 version. Finally, comparisons of the 'total' program execution times (multiplications, additions, and data transfers, but not indexing or permutations) are presented.

Nawab, H.↗
NASA NTRS1974

Model wall and recovery temperature effects on experimental heat transfer data analysis

Basic analytical procedures are used to illustrate, both qualitatively and quantitatively, the relative impact upon heat transfer data analysis of certain factors which may affect the accuracy of experimental heat transfer data. Inaccurate knowledge of adiabatic wall conditions results in a corresponding inaccuracy in the measured heat transfer coefficient. The magnitude of the resulting error is extreme for data obtained at wall temperatures approaching the adiabatic condition. High model wall temperatures and wall temperature gradients affect the level and distribution of heat transfer to an experimental model. The significance of each of these factors is examined and its impact upon heat transfer data analysis is assessed.

Throckmorton, D. A.↗
NASA NTRS1971

Data transfer system Patent

Data acquisition and processing system with buffer storage and timing device for magnetic tape recording of PCM data and timing information

Coolidge, J. E.↗
DOE OSTI2024

Characterization of throughput on the AXI DMA bus for burst data transfer over Ethernet

cThe Xilinx AXI Direct Memory Access (AXI DMA) module is an efficient solution for medium-speed data transfer in Xilinx SoC FPGAs, supporting data rates greater than 1000 Gbps even in very suboptimal operating modes. It facilitates direct transfer of AXI stream data into processor memory without constant software intervention, which reduces overhead and ensures consistent data logging. By utilizing the FPGA's available memory, large circular buffers (1-5 GiB) are used to buffer data and accommodate network limitations, enabling high-rate data bursts. In this study, we measured the performance of AXI DMA under conditions simulating its lowest practical data transfer speeds. The Arbitrary Length Data Sender was used to transmit AXI stream packets at 32-bit width and 100 MHz frequency, a narrow width and slow speed. Results show that the AXI DMA can transfer up to 3192.76 Mbps with large packet sizes but experiences reduced performance for smaller packets, as low as 2.6 Mbps for 4-byte packets. For Ethernet-limited applications, packet sizes between 8,000 and 16,000 bytes provided optimal transfer speeds of 874 to 1600 Mbps. These findings suggest that the AXI DMA is not the limiting factor in systems where packet sizes exceed 8,000 bytes.

43 PARTICLE ACCELERATORS↗
NASA NTRS1982

Preliminary Analysis of STS-3 Entry Heat-Transfer Data for the Orbiter Windward Centerline

A preliminary analysis of heat transfer data on the space shuttle orbiter windward centerline for the STS-3 mission entry is presented. Temperature-time history plots for each measurement location and tabulated wall temperature and convective heating rate data at 21 selected trajectory points are included. The STS-3 flight data are also compared with predictions by two approximation methods for computing convective heat transfer rates in equilibrium air.

Throckmorton, D. A.↗
NASA NTRS1970

Heat-transfer data for hydrogen

Information is given regarding experimental heat-transfer data compiled for the turbulent flow of hydrogen within straight, electrically heated, round cross section tubes. Tube materials, test conditions, parameters studied, and generalized conclusions are presented.

Mc Carthy, J. R.↗
NASA NTRS1978

Undisturbed heat transfer data analysis on the Space Shuttle External Tank Barrel Section

The paper analyzes the existing continuum undisturbed turbulent heat transfer data on smooth models of the Space Shuttle External Tank and develops a mathematical model for theoretical prediction of heat transfer rates on the External Tank Barrel Section. Experimental data have been obtained from various wind tunnels which simulated the continuum flow regime in the Shuttle flight trajectory. The model data have been compared with theoretical predictions using realistic flow fields and well-known empirical heat transfer relationships. The results show that the predictions are good to within the experimental uncertainties of the measured data.

Praharaj, S. C.↗
NASA NTRS1975

Satellite system considerations for computer data transfer

Communications satellites will play a key role in the transmission of computer generated data through nationwide networks. This paper examines critical aspects of satellite system design as they relate to the computer data transfer task. In addition, it discusses the factors influencing the choice of error control technique, modulation scheme, multiple-access mode, and satellite beam configuration based on an evaluation of system requirements for a broad range of application areas including telemetry, terminal dialog, and bulk data transmission.

Cook, W. L.↗
NASA NTRS1971

Thermal Analysis Methods and Basic Heat-Transfer Data for a Turbulent Heating Flight Experiment at Mach 20 (Reentry F)

A heat-transfer experiment was flight conducted on a 5 deg half-angle cone, 396.2 cm (13 ft) in length, as it entered the sensible atmosphere under laminar, transitional, and turbulent boundary-layer conditions at a free-stream Mach number of about 20. Accurate turbulent-heat-transfer data with natural transition were obtained for correlation with theories in regions of simultaneous high Mach number, Reynolds number, enthalpy, and total-to-wall temperature ratio. Temperatures were measured at four depths through the 15.24-mm-thick (0.600-in.) beryllium wall. Experimental heating rates at 20 stations on the cone were determined independently from the outermost temperature measurement and from the temperature measurement at the second depth by a single-thermocouple inverse method and also from the temperature histories at all four depths by an integral method. The thermal data analysis procedure, associated problems, and results are presented herein.

Howard, Floyd G.↗
NASA NTRS1982

Benchmark aerodynamic heat-transfer data from the first flight of the Space Shuttle Orbiter

Benchmark entry aerodynamic heat-transfer data were determined from the first flight of the Space Shuttle Orbiter. The convective heating-rate data result from a rigorous mathematical analysis of one-dimensional, transient heat conduction within the orbiter thermal protection system (TPS) and reradiation from its surface during entry. Temperatures measured at the TPS surface during orbiter entry provide a constraint to the analysis. On the vehicle leeside, where heating rate levels are low, corrections are made to the computed convective heating rates to account for solar radiation and cross-radiation between fuselage and wing surfaces. The source of the entry thermal data, the mathematical analysis technique, and the TPS thermal models are discussed. Typical convective heating rate data from the STS-1 mission are presented.

Throckmorton, D. A.↗
DOE OSTI2025

Data Management in the Continuum: Cross-facility Object-based Data Transfers

Scientific workflows are evolving from relying on a monolithic storage subsystem at a single High-Performance Computing (HPC) facility to using geographically distributed file systems, repositories, and cloud storage. As a result, storing, accessing, transferring, and managing scientific data have become highly complex and prone to performance inefficiencies. This paper delves into these challenges by exploring an optimized end-to-end interface designed to seamlessly connect various local and remote storage systems, enabling efficient data movement of objects across HPC–Cloud and HPC–HPC environments. We showcase this capability through an object-focused data management runtime system, discuss the effects of relaxed consistency semantics in distributed object scenarios, and illustrate its application in an earthquake simulation workflow. Besides reducing the amount of data by selectively transferring regions of interest, our facility-local results achieved a speedup of 45 × over an optimized HDF5 usage and 15 × over the HDF5 with caching by using the new interface in PDC-XF.

Bez, Jean Luca↗
NASA NTRS1972

An improved data transfer and storage technique for hybrid computation

Improved technique was developed for transferring and storing data at faster than real time speeds on hybrid computer. Predominant advantage is combined use of electronic relays, track and store units, and analog-to-digital and digital-to-analog conversion units of hybrid computer.

Hansing, A. M.↗