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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 649 records · Page 36
All sourcesNASA NTRSDOE OSTI
NASA NTRS2009

Orion Service Module Reaction Control System Plume Impingement Analysis Using PLIMP/RAMP2

The Orion Crew Exploration Vehicle Service Module Reaction Control System engine plume impingement was computed using the plume impingement program (PLIMP). PLIMP uses the plume solution from RAMP2, which is the refined version of the reacting and multiphase program (RAMP) code. The heating rate and pressure (force and moment) on surfaces or components of the Service Module were computed. The RAMP2 solution of the flow field inside the engine and the plume was compared with those computed using GASP, a computational fluid dynamics code, showing reasonable agreement. The computed heating rate and pressure using PLIMP were compared with the Reaction Control System plume model (RPM) solution and the plume impingement dynamics (PIDYN) solution. RPM uses the GASP-based plume solution, whereas PIDYN uses the SCARF plume solution. Three sets of the heating rate and pressure solutions agree well. Further thermal analysis on the avionic ring of the Service Module showed that thermal protection is necessary because of significant heating from the plume.

Wang, Xiao-Yen J.↗
NASA NTRS2009

Orion Service Module Reaction Control System Plume Impingement Analysis Using PLIMP/RAMP2

The Orion Crew Exploration Vehicle Service Module Reaction Control System engine plume impingement was computed using the plume impingement program (PLIMP). PLIMP uses the plume solution from RAMP2, which is the refined version of the reacting and multiphase program (RAMP) code. The heating rate and pressure (force and moment) on surfaces or components of the Service Module were computed. The RAMP2 solution of the flow field inside the engine and the plume was compared with those computed using GASP, a computational fluid dynamics code, showing reasonable agreement. The computed heating rate and pressure using PLIMP were compared with the Reaction Control System plume model (RPM) solution and the plume impingement dynamics (PIDYN) solution. RPM uses the GASP-based plume solution, whereas PIDYN uses the SCARF plume solution. Three sets of the heating rate and pressure solutions agree well. Further thermal analysis on the avionic ring of the Service Module was performed using MSC Patran/Pthermal. The obtained temperature results showed that thermal protection is necessary because of significant heating from the plume.

Wang, Xiao-Yen↗
NASA NTRS1976

Integration of a code for aeroelastic design of conventional and composite wings into ACSYNT, an aircraft synthesis program

A comparison of program estimates of wing weight, material distribution. structural loads and elastic deformations with actual Northrop F-5A/B data is presented. Correlation coefficients obtained using data from a number of existing aircraft were computed for use in vehicle synthesis to estimate wing weights. The modifications necessary to adapt the WADES code for use in the ACSYNT program are described. Basic program flow and overlay structure is outlined. An example of the convergence of the procedure in estimating wing weights during the synthesis of a vehicle to satisfy F-5 mission requirements is given. A description of inputs required for use of the WADES program is included.

Mullen, J., Jr.↗
NASA NTRS1986

Multidisciplinary analysis of actively controlled large flexible spacecraft

The control of Flexible Structures (COFS) program has supported the development of an analysis capability at the Langley Research Center called the Integrated Multidisciplinary Analysis Tool (IMAT) which provides an efficient data storage and transfer capability among commercial computer codes to aid in the dynamic analysis of actively controlled structures. IMAT is a system of computer programs which transfers Computer-Aided-Design (CAD) configurations, structural finite element models, material property and stress information, structural and rigid-body dynamic model information, and linear system matrices for control law formulation among various commercial applications programs through a common database. Although general in its formulation, IMAT was developed specifically to aid in the evaluation of the structures. A description of the IMAT system and results of an application of the system are given.

Cooper, Paul A.↗
NASA NTRSDate not supplied

An Interactive MATLAB Program for Fitting Transfer Functions to Frequency Responses

A computer program called FRFit (Frequency Response Fitting) is described for fitting single-input single-output transfer function models to empirical frequency response data. The program is interactive in that the user specifies ``elementary factors'' (gain, delay, pure differentiators and integrators, and first- and second-order zeros and poles) by entering numerical values or moving sliders in a graphical user interface. A nonlinear optimization can then be performed to obtain maximum likelihood estimates of transfer function parameters and uncertainties to provide feedback on the modeling and refine estimates. Several examples are discussed, including the identification of aircraft pitch dynamics from simulation data and data reported in the literature, approximating Theodorsen's function of unsteady aerodynamics, and obtaining a reduced-order model of a computational fluid dynamics code describing the unsteady aerodynamics around an aeroelastic wing. The program has some usefulness as a teaching aid, and can be applied to model structure determination, reduced-order modeling, preliminary analysis, and simple system identification problems. The program was written in MATLAB and is planned for public release through the NASA Software Catalog.

System identification↗
NASA NTRS1978

Upgraded viscous flow analysis of multielement airfoils

A description of an improved version of the NASA/Lockheed multielement airfoil analysis computer program is presented. The improvements include several major modifications of the aerodynamic model as well as substantial changes of the computer code. The modifications of the aerodynamic model comprise the representation of the boundary layer and wake displacement effects with an equivalent source distribution, the prediction of wake parameters with Green's lag-entrainment method, the calculation of turbulent boundary layer separation with the method of Nash and Hicks, the estimation of the onset of confluent boundary layer separation with a modified form of Goradia's method, and the prediction of profile drag with the formula of Squire and Young. The paper further describes the modifications of the computer program for which the structured approach to computer software development was employed. Important aspects of the structured program development such as the functional decomposition of the aerodynamic theory and its numerical implementation, the analysis of the data flow within the code, and the application of a pseudo code are discussed.

Brune, G. W.↗
NASA NTRS1977

SUNSPOT: A computer program for producing optimal solar sail planetocentric trajectories

The input, output and subroutines, including listings, for the SUNSPOT code are described. SUNSPOT can calculate time optimal planetocentric trajectories including orbit-to-orbit transfer and orbit to a subescape point. Trajectories about the the four inner planets can be calculated, and shadowing, oblateness, and solar motion may be included. A penalty function may be included to prevent trajectories which intersect the planet's surface.

Sackett, L. L.↗
NASA NTRS1996

Overview of HATP Experimental Aerodynamics Data for the Baseline F/A-18 Configuration

Determining the baseline aerodynamics of the F/A-18 was one of the major objectives of the High-Angle-of-Attack Technology Program (HATP). This paper will review the key data bases that have contributed to our knowledge of the baseline aerodynamics and the improvements in test techniques that have resulted from the experimental program. Photographs are given highlighting the forebody and leading-edge-extension (LEX) vortices. Other data representing the impact of Mach and Reynolds numbers on the forebody and LEX vortices will also be detailed. The level of agreement between different tunnels and between tunnels and flight will be illustrated using pressures, forces, and moments measured on a 0.06-scale model tested in the Langley 7- by 10-Foot High Speed Tunnel, a 0.16-scale model in the Langley 30- by 60-Foot Tunnel, a full-scale vehicle in the Ames 80- by 120-Foot Wind Tunnel, and the flight F/A-18 High Alpha Research Vehicle (HARV). Next, creative use of wind tunnel resources that accelerated the validation of the computational fluid dynamics (CFD) codes will be described. Lastly, lessons learned, deliverables, and program conclusions are presented.

Hall, Robert M.↗
NASA NTRS1979

Detailed description of the HP-9825A HFRMP trajectory processor (TRAJ)

The computer code for the trajectory processor of the HP-9825A High Fidelity Relative Motion Program is described in detail. The processor is a 12-degrees-of-freedom trajectory integrator which can be used to generate digital and graphical data describing the relative motion of the Space Shuttle Orbiter and a free-flying cylindrical payload. Coding standards and flow charts are given and the computational logic is discussed.

Kindall, S. M.↗
NASA NTRS2005

ANTLR Tree Grammar Generator and Extensions

A computer program implements two extensions of ANTLR (Another Tool for Language Recognition), which is a set of software tools for translating source codes between different computing languages. ANTLR supports predicated- LL(k) lexer and parser grammars, a notation for annotating parser grammars to direct tree construction, and predicated tree grammars. [ LL(k) signifies left-right, leftmost derivation with k tokens of look-ahead, referring to certain characteristics of a grammar.] One of the extensions is a syntax for tree transformations. The other extension is the generation of tree grammars from annotated parser or input tree grammars. These extensions can simplify the process of generating source-to-source language translators and they make possible an approach, called "polyphase parsing," to translation between computing languages. The typical approach to translator development is to identify high-level semantic constructs such as "expressions," "declarations," and "definitions" as fundamental building blocks in the grammar specification used for language recognition. The polyphase approach is to lump ambiguous syntactic constructs during parsing and then disambiguate the alternatives in subsequent tree transformation passes. Polyphase parsing is believed to be useful for generating efficient recognizers for C++ and other languages that, like C++, have significant ambiguities.

Craymer, Loring↗
NASA NTRS1971

A study of the electromagnetic interaction between planetary bodies and the solar wind

Theoretical and computational techniques were developed for calculating the time dependent electromagnetic response of a radially inhomogeneous moon. The techniques were used to analyze the experimental data from the LSM (lunar surface magnetometer) thus providing an in-depth diagnostic of the Lunar interior. The theory was also incorporated into an existing computer code designed to calculate the thermal evolution of planetary bodies. The program will provide a tool for examining the effect of heating from the TE mode (poloidal magnetic field) as well as the TM mode (toroidal magnetic field).

Schwartz, K.↗
NASA NTRS1972

Astronauts' menu problem.

Consideration of the problems involved in choosing appropriate menus for astronauts carrying out SKYLAB missions lasting up to eight weeks. The problem of planning balanced menus on the basis of prepackaged food items within limitations on the intake of calories, protein, and certain elements is noted, as well as a number of other restrictions of both physical and arbitrary nature. The tailoring of a set of menus for each astronaut on the basis of subjective rankings of each food by the astronaut in terms of a 'measure of pleasure' is described, and a computer solution to this problem by means of a mixed integer programming code is presented.

Lesso, W. G.↗
NASA NTRS1974

Buckling of conical shell with local imperfections

Small geometric imperfections in thin-walled shell structures can cause large reductions in buckling strength. Most imperfections found in structures are neither axisymmetric nor have the shape of buckling modes but rather occur locally. This report presents the results of a study of the effect of local imperfections on the critical buckling load of a specific axially compressed thin-walled conical shell. The buckling calculations were performed by using a two-dimensional shell analysis program referred to as the STAGS (Structural Analysis of General Shells) computer code, which has no axisymmetry restrictions. Results show that the buckling load found from a bifurcation buckling analysis is highly dependent on the circumferential arc length of the imperfection type studied. As the circumferential arc length of the imperfection is increased, a reduction of up to 50 percent of the critical load of the perfect shell can occur. The buckling load of the cone with an axisymmetric imperfections is nearly equal to the buckling load of imperfections which extended 60 deg or more around the circumference, but would give a highly conservative estimate of the buckling load of a shell with an imperfection of a more local nature.

Cooper, P. A.↗
NASA NTRS1984

Progress toward the development of an aircraft icing analysis capability

An overview of the NASA efforts to develop an aircraft icing analysis capability is presented. Discussions are included of the overall and long term objectives of the program as well as current capabilities and limitations of the various computer codes being developed. Descriptions are given of codes being developed to analyze two and three dimensional trajectories of water droplets, airfoil ice accretion, aerodynamic performance degradation of components and complete aircraft configurations, electrothermal deicer, and fluid freezing point depressant deicer. The need for bench mark and verification data to support the code development is also discussed.

Shaw, R. J.↗
NASA NTRS1984

Progress toward the development of an aircraft icing analysis capability

An overview of the NASA efforts to develop an aircraft icing analysis capability is presented. Discussions are included of the overall and long term objectives of the program as well as current capabilities and limitations of the various computer codes being developed. Descriptions are given of codes being developed to analyze two and three dimensional trajectories of water droplets, airfoil ice accretion, aerodynamic performance degradation of components and complete aircraft configurations, electrothermal deicer, and fluid freezing point depressant deicer. The need for bench mark and verification data to support the code development is also discussed.

Shaw, R. J.↗
NASA NTRS1987

Nonlinear shell analyses of the SRB/ETA ring interface

Two-dimensional shell models of the portion of the solid rocket booster (SRB) with the external tank attachment (ETA) ring were developed using the STAGSC-1 computer code. These analyses were performed in support of the SRB recertification program underway at the NASA Marshall Space Flight Center. The purpose of these analyses is to calculate the overall stress and deflection distributions for the SRB/ETA ring interface. An overview of the SRB/ETA ring geometry is presented followed by a discussion of the analysis methods and finite element models. Finally, the nonlinear structural response of the SRB/ETA ring interface is discussed.

Knight, Norman F., Jr.↗