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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 343 records · Page 19
All sourcesNASA NTRSDOE OSTI
NASA NTRS1974

Application of an improved unified subsonic-supersonic potential flow method for the aerodynamic analysis of aircraft configurations

F. A. Woodward, under contract to the NASA Langley Research Center, has recently formulated a distributed vortex aerodynamic singularity and developed an improved unified subsonic-supersonic potential flow computer program employing this singularity. This improved program is applicable to the prediction of the local surface pressure distribution for a large class of essentially arbitrarily shaped aircraft configurations. Results are presented for two classes of aircraft configurations of current interest: a maneuvering fighter type and a supersonic transport type. Comparison of these results with experiment indicate the program has good prediction capability.

Fox, C. H., Jr.↗
NASA NTRS1972

Acoustic attenuation analysis program for ducts with mean flow

A computerized acoustic attenuation prediction procedure has been developed to evaluate acoustically lined ducts for various geometric and environmental parameters. The analysis procedure is based on solutions to the acoustic wave equation, assuming uniform airflow on a duct cross section, combined with appropriate mathematical lining impedance models. The impedance models included in the analysis procedure are representative of either perforated sheet or porous polyimide impregnated fiberglass facing sheet coupled with a cellular backing space. Advantages and limitations of the analysis procedure are reviewed.

Kunze, R. K., Jr.↗
NASA NTRS1974

Reduction and error analysis of the AVE 2 pilot experiment data

The reduction techniques used to process data from the pilot experiment of the second NASA atmospheric variability experiment (AVE IIP), which was conducted during a 24 hour period beginning at 1200 GMT on May 11, 1974, and ending at 1200 GMT on May 12, 1974 are described. Each step of the data handling process is described through the presentation of computer flow charts, programs, equations, and narrative. An error analysis of the final output is presented, and results of the AVE IIP reduction process are compared with results from the National Weather Service. The AVE IIP sounding data contain more detail than National Weather Service data, but the two data sets may be used together without difficulty.

Fuelberg, H. E.↗
NASA NTRS1976

Improving aircraft energy efficiency

Investigations conducted by a NASA task force concerning the development of aeronautical fuel-conservation technology are considered. The task force estimated the fuel savings potential, prospects for implementation in the civil air-transport fleet, and the impact of the technology on air-transport fuel use. Propulsion advances are related to existing engines in the fleet, to new production of current engine types, and to new engine designs. Studies aimed at the evolutionary improvement of aerodynamic design and a laminar flow control program are discussed and possibilities concerning the use of composite structural materials are examined.

Povinelli, F. P.↗
NASA NTRS1978

A perspective of laminar-flow control

A historical review of the development of laminar flow control technology is presented with reference to active laminar boundary-layer control through suction, the use of multiple suction slots, wind-tunnel tests, continuous suction, and spanwise contamination. The ACEE laminar flow control program is outlined noting the development of three-dimensional boundary-layer codes, cruise-noise prediction techniques, airfoil development, and leading-edge region cleaning. Attention is given to glove flight tests and the fabrication and testing of wing box designs.

Braslow, A. L.↗
NASA NTRS1979

Bumblebee program, aerodynamic data. Part 2: Flow fields at Mach number 2.0

Available flow field data which can be used in validating theoretical procedures for computing flow fields around supersonic missiles are presented. Tabulated test data are given which define the flow field around a conical-nosed cylindrical body in a crossflow plane corresponding to a likely tail location. The data were obtained at a Mach number of 2.0 for an angle of attack of 0 to 23 degrees. The data define the flow field for cases both with and without a forward wing present.

Barnes, G. A.↗
NASA NTRS1978

Documentation of a ground hydrology parameterization for use in the GISS atmospheric general circulation model

The moisture transport processes related to the earth's surface relevant to the ground circulation model GCM are presented. The GHM parametrizations considered are: (1) ground wetness and soil parameters; (2) precipitation; (3) evapotranspiration; (4) surface storage of snow and ice; and (5) runout. The computational aspects of the GHM using computer programs and flow charts are described.

Lin, J. D.↗
NASA NTRS1981

Inviscid transonic flow over axisymmetric bodies

Axisymmetric transonic flow is of interest not only because of its practical application to missile and launch vehicle aerodynamics but also because of its relation, in terms of area rule, to fully three dimensional flow. RAXBOD computer program analyzes steady, inviscid, irrotational, transonic flow over axisymmetric bodies in free air. RAXBOD uses finite-difference relaxation method to solve numerically exact formulation of disturbance velocity potential with exact surface boundary conditions. Agreement with available experimental results has been good in cases where viscous effects and wind-tunnel wall interference are not important.

South, J. C., Jr.↗
NASA NTRS1980

Calculation of laminar heating rates on three-dimensional configurations using the axisymmetric analogue

A theoretical method was developed for computing approximate laminar heating rates on three dimensional configurations at angle of attack. The method is based on the axisymmetric analogue which is used to reduce the three dimensional boundary layer equations along surface streamlines to an equivalent axisymmetric form by using the metric coefficient which describes streamline divergence (or convergence). The method was coupled with a three dimensional inviscid flow field program for computing surface streamline paths, metric coefficients, and boundary layer edge conditions.

Hamilton, H. H., II↗
NASA NTRS1981

Blade loss transient dynamics analysis. Volume 3: User's manual for TETRA program

The users manual for TETRA contains program logic, flow charts, error messages, input sheets, modeling instructions, option descriptions, input variable descriptions, and demonstration problems. The process of obtaining a NASTRAN 17.5 generated modal input file for TETRA is also described with a worked sample.

Black, G. R.↗
NASA NTRS1981

Program of Research in Laminar Flow Control in the JIAFS at NASA Langley Research Center

At high Reynolds numbers, the performance of a low drag suction LFC airplane is essentially controlled by the induced drag and the turbulent friction drag of the nonlaminarized area. The question then arises as to how the airplane cruise lift to drag ratio (L/D) sub cruise) cruise increases with increasing extent of laminar flow 0 sub lam./0 sub total (0 = airplane wetted area). In particular, the question arises as to the airplane performance in the optimum case with all laminar flow over the airplane wetted area. Design approaches of all laminar flow LFC airplanes which optimize the airplane range . R = eta sub ov times (L/D) times H times lambda n(W sub 0/W sub E) are considered.

Pfenninger, W.↗
NASA NTRS1983

Use of CYBER 203 and CYBER 205 computers for three-dimensional transonic flow calculations

Experiences are discussed for modifying two three-dimensional transonic flow computer programs (FLO 22 and FLO 27) for use on the CDC CYBER 203 computer system. Both programs were originally written for use on serial machines. Several methods were attempted to optimize the execution of the two programs on the vector machine: leaving the program in a scalar form (i.e., serial computation) with compiler software used to optimize and vectorize the program, vectorizing parts of the existing algorithm in the program, and incorporating a vectorizable algorithm (ZEBRA I or ZEBRA II) in the program. Comparison runs of the programs were made on CDC CYBER 175. CYBER 203, and two pipe CDC CYBER 205 computer systems.

Melson, N. D.↗
NASA NTRS1984

Operating system for a real-time multiprocessor propulsion system simulator

The success of the Real Time Multiprocessor Operating System (RTMPOS) in the development and evaluation of experimental hardware and software systems for real time interactive simulation of air breathing propulsion systems was evaluated. The Real Time Multiprocessor Operating System (RTMPOS) provides the user with a versatile, interactive means for loading, running, debugging and obtaining results from a multiprocessor based simulator. A front end processor (FEP) serves as the simulator controller and interface between the user and the simulator. These functions are facilitated by the RTMPOS which resides on the FEP. The RTMPOS acts in conjunction with the FEP's manufacturer supplied disk operating system that provides typical utilities like an assembler, linkage editor, text editor, file handling services, etc. Once a simulation is formulated, the RTMPOS provides for engineering level, run time operations such as loading, modifying and specifying computation flow of programs, simulator mode control, data handling and run time monitoring. Run time monitoring is a powerful feature of RTMPOS that allows the user to record all actions taken during a simulation session and to receive advisories from the simulator via the FEP. The RTMPOS is programmed mainly in PASCAL along with some assembly language routines. The RTMPOS software is easily modified to be applicable to hardware from different manufacturers.

Cole, G. L.↗
NASA NTRS1982

Gas flow environment and heat transfer nonrotating 3D program

A complete set of benchmark quality data for the flow and heat transfer within a large rectangular turning duct is provided. These data are to be used to evaluate, and verify, three-dimensional internal viscous flow models and computational codes. The analytical contract objective is to select a computational code and define the capabilities of this code to predict the experimental results obtained. Details of the proper code operation will be defined and improvements to the code modeling capabilities will be formulated. Internal flow in a large rectangular cross-sectioned 90 deg. bend turning duct was studied. The duct construction was designed to allow detailed measurements to be made for the following three duct wall conditions: (1) an isothermal wall with isothermal flow; (2) an adiabatic wall with convective heat transfer by mixing between an unheated surrounding flow; and (3) an isothermal wall with heat transfer from a uniformly hot inlet flow.

Schulz, R. J.↗
NASA NTRS1984

Helicopter noise as predicted by three-dimensional monopole and quasi-steady full-potential dipole sources

A three-dimensional quasi-steady full-potential rotor-flow-analysis program, called ROT22 developed at NASA Ames Research Center is run in conjunction with Farassat's (1981) helicopter-noise-prediction code to assess the thickness and loading noises made by a rotor blade. As a model example, the case of a 1/7th UH-1H NACA-0012-profile straight nonlifting rotor blade in hover is studied. Results for tip Mach numbers ranging from .4 to .962 are presented. Also presented is the effect of blade-tip loading on the overall noise and of profile curvature on the thickness noise. The study confirms that the blade volume displacement is a dominant source of helicopter noise and further concludes that the blade tip makes only a small noise contribution that steadily decreases with increasing tip Mach numbers, and that the inclusion of blade profile curvature tends to improve the negative peak amplitudes overpredicted by Schmitz and Yu (1983).

Aggarwal, H. R.↗
NASA NTRS1983

Gas flow environmental and heat transfer nonrotating 3D program

A complete set of benchmark quality data for the flow and heat transfer within a large rectangular turning duct is being compiled. These data will be used to evaluate and verify three dimensional internal viscous flow models and computational codes. The analytical objective is to select such a computational code and define the capabilities of this code to predict the experimental results. Details of the proper code operation will be defined and improvements to the code modeling capabilities will be formulated.

Geil, T.↗
NASA NTRS1984

Evaluation of automated decisionmaking methodologies and development of an integrated robotic system simulation, appendix B

The purpose of the Robotics Simulation (ROBSIM) program is to provide a broad range of computer capabilities to assist in the design, verification, simulation, and study of robotic systems. ROBSIM is programmed in FORTRAN 77 and implemented on a VAX 11/750 computer using the VMS operating system. This programmer's guide describes the ROBSIM implementation and program logic flow, and the functions and structures of the different subroutines. With this manual and the in-code documentation, and experienced programmer can incorporate additional routines and modify existing ones to add desired capabilities.

Haley, D. C.↗