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All sourcesNASA NTRSDOE OSTI
NASA NTRS1990

A package for 3-D unstructured grid generation, finite-element flow solution and flow field visualization

A set of computer programs for 3-D unstructured grid generation, fluid flow calculations, and flow field visualization was developed. The grid generation program, called VGRID3D, generates grids over complex configurations using the advancing front method. In this method, the point and element generation is accomplished simultaneously, VPLOT3D is an interactive, menudriven pre- and post-processor graphics program for interpolation and display of unstructured grid data. The flow solver, VFLOW3D, is an Euler equation solver based on an explicit, two-step, Taylor-Galerkin algorithm which uses the Flux Corrected Transport (FCT) concept for a wriggle-free solution. Using these programs, increasingly complex 3-D configurations of interest to aerospace community were gridded including a complete Space Transportation System comprised of the space-shuttle orbitor, the solid-rocket boosters, and the external tank. Flow solutions were obtained on various configurations in subsonic, transonic, and supersonic flow regimes.

Parikh, Paresh↗
NASA NTRS1997

Use of Variable Angle Spectroscopic Ellipsometry in Order to Determine Contaminant Optical Properties

In order to measure contaminant levels found in the manufacture of the Redesigned Solid Rocket Motor (RSRM), optical properties of the contaminants are needed to develop standards for calibration purposes. Specific to our efforts is the determination of the complex index of refraction for a hydrocarbon mixture and a commercial methyl siloxane. Using ellipsometric measurements with multiple angles of incident and a range of wavelengths in the near infrared a determination of the index of refraction and the extinction coefficient were made for the contaminants. This paper will present the optical techniques and modeling approach used to determine these optical constants of the hydrocarbon mixture and the methyl siloxane studied.

Hughes, C.↗
NASA NTRS2001

Microgravity Combustion Science and Fluid Physics Experiments and Facilities for the ISS

At the NASA Glenn Research Center, the Microgravity Science Program supports both ground-based and flight experiment research in the disciplines of Combustion Science and Fluid Physics. Combustion Science research includes the areas of gas jet diffusion flames, laminar flames, burning of droplets and misting fuels, solids and materials flammability, fire and fire suppressants, turbulent combustion, reaction kinetics, materials synthesis, and other combustion systems. The Fluid Physics discipline includes the areas of complex fluids (colloids, gels, foams, magneto-rheological fluids, non-Newtonian fluids, suspensions, granular materials), dynamics and instabilities (bubble and drop dynamics, magneto/electrohydrodynamics, electrochemical transport, geophysical flows), interfacial phenomena (wetting, capillarity, contact line hydrodynamics), and multiphase flows and phase changes (boiling and condensation, heat transfer, flow instabilities). A specialized International Space Station (ISS) facility that provides sophisticated research capabilities for these disciplines is the Fluids and Combustion Facility (FCF). The FCF consists of the Combustion Integrated Rack (CIR), the Fluids Integrated Rack (FIR) and the Shared Accommodations Rack and is designed to accomplish a large number of science investigations over the life of the ISS. The modular, multiuser facility is designed to optimize the science return within the available resources of on-orbit power, uplink/downlink capacity, crew time, upmass/downmass, volume, etc. A suite of diagnostics capabilities, with emphasis on optical techniques, will be provided to complement the capabilities of the subsystem multiuser or principal investigator-specific experiment modules. The paper will discuss the systems concept, technical capabilities, functionality, and the initial science investigations in each discipline.

Lauver, Richard W.↗
NASA NTRS1997

Shuttle Fire Tests Are Radiant

Flame spreading is a phenomenon familiar to everyone who has witnessed an accidental fire. Yet, because of the complexity of the physical and chemical processes that are involved, the theoretical understanding of fires and flame spreading is a relatively new science. Flames spread along solid materials in a process where heat from the flames vaporizes the fuel just ahead of the moving flame. The vaporized fuel mixes with oxygen from the air and reacts chemically with it, producing the flame. On Earth, the spread rate of the flame is directly affected by the rate at which the fuel and oxygen are mixed with the help of buoyant convection.

Olson, Sandra L.↗
NASA NTRS2008

NASA Tech Briefs, June 2008

Topics covered include: Charge-Control Unit for Testing Lithium-Ion Cells; Measuring Positions of Objects Using Two or More Cameras; Lidar System for Airborne Measurement of Clouds and Aerosols; Radiation-Insensitive Inverse Majority Gates; Reduced-Order Kalman Filtering for Processing Relative Measurements; Spaceborne Processor Array; Instrumentation System Diagnoses a Thermocouple; Chromatic Modulator for a High-Resolution CCD or APS; Commercial Product Activation Using RFID; Cup Cylindrical Waveguide Antenna; Aerobraking Maneuver (ABM) Report Generator; ABM Drag_Pass Report Generator; Transformation of OODT CAS to Perform Larger Tasks; Visualization Component of Vehicle Health Decision Support System; Mars Reconnaissance Orbiter Uplink Analysis Tool; Problem Reporting System; G-Guidance Interface Design for Small Body Mission Simulation; DSN Scheduling Engine; Replacement Sequence of Events Generator; Force-Control Algorithm for Surface Sampling; Tool for Merging Proposals Into DSN Schedules; Micromachined Slits for Imaging Spectrometers; Fabricating Nanodots Using Lift-Off of a Nanopore Template; Making Complex Electrically Conductive Patterns on Cloth; Special Polymer/Carbon Composite Films for Detecting SO2; Nickel-Based Superalloy Resists Embrittlement by Hydrogen; Chemical Passivation of Li+-Conducting Solid Electrolytes; Organic/Inorganic Polymeric Composites for Heat-Transfer Reduction; Composite Cathodes for Dual-Rate Li-Ion Batteries; Improved Descent-Rate Limiting Mechanism; Alignment-Insensitive Lower-Cost Telescope Architecture; Micro-Resistojet for Small Satellites; Using Piezoelectric Devices to Transmit Power through Walls; Miniature Latching Valve; Apparatus for Sampling Surface Contamination; Novel Species of Non-Spore-Forming Bacteria; Chamber for Aerosol Deposition of Bioparticles; Hyperspectral Sun Photometer for Atmospheric Characterization and Vicarious Calibrations; Dynamic Stability and Gravitational Balancing of Multiple Extended Bodies; Simulation of Stochastic Processes by Coupled ODE-PDE; Cluster Inter-Spacecraft Communications; Genetic Algorithm Optimizes Q-LAW Control Parameters; Low-Impact Mating System for Docking Spacecraft; Non-Destructive Evaluation of Materials via Ultraviolet Spectroscopy; Gold-on-Polymer-Based Sensing Films for Detection of Organic and Inorganic Analytes in the Air; and Quantum-Inspired Maximizer.

Source record↗
NASA NTRS2014

Mean Flow Augmented Acoustics in Rocket Systems

Combustion instability in solid rocket motors and liquid engines has long been a subject of concern. Many rockets display violent fluctuations in pressure, velocity, and temperature originating from the complex interactions between the combustion process and gas dynamics. Recent advances in energy based modeling of combustion instabilities require accurate determination of acoustic frequencies and mode shapes. Of particular interest is the acoustic mean flow interactions within the converging section of a rocket nozzle, where gradients of pressure, density, and velocity become large. The expulsion of unsteady energy through the nozzle of a rocket is identified as the predominate source of acoustic damping for most rocket systems. Recently, an approach to address nozzle damping with mean flow effects was implemented by French [1]. This new approach extends the work originated by Sigman and Zinn [2] by solving the acoustic velocity potential equation (AVPE) formulated by perturbing the Euler equations [3]. The present study aims to implement the French model within the COMSOL Multiphysiscs framework and analyzes one of the author's presented test cases.

Fischbach, Sean↗
NASA NTRS2019

A Composite Damage Tolerance Simulation Technique to Augment the Building Block Approach

Aerospace structures comprised of composite materials are traditionally certified empirically via the Building Block Approach (BBA). While this approach has been performed successfully in the past, it is expensive and time consuming. One means to improve the overall efficiency of composite structural certification is to reduce the cost of the BAA by eliminating the need for some tests by incorporating damage analysis tools. For an analysis to replace a given test, the tool must first be validated using other similar test data. The subject of this paper is a description of an analysis technique for simulating compression after damage strength of a solid laminate. The analysis technique is one that is practical for use in an applied engineering context due to efforts to minimize necessary computational resources and complexity of the model.

McElroy, Mark↗
NASA NTRS2019

A Composite Damage Tolerance Simulation Technique to Augment the Building Block Approach

Aerospace structures comprised of composite materials are traditionally certified empirically via the Building Block Approach (BBA). While this approach has been performed successfully in the past, it is expensive and time-consuming. One means to improve the overall efficiency of composite structural certification is to reduce the cost of the BBA by eliminating the need for some tests by incorporating damage analysis tools. For an analysis to replace a given test, the tool must first be validated using other similar test data. The subject of this paper is a description of an efficient analysis technique for simulating compression after damage strength of a solid laminate. The analysis technique is one that is practical for use in an applied engineering context due to efforts to minimize necessary computational resources and complexity of the model.

McElroy, Mack↗
NASA NTRSDate not supplied

The Nature of Extraterrestrial Amino Acids in Carbonaceous Chondrites and Links to Their Parent Bodies

Meteorites and samples returned from asteroids and comets provide an important record of the physical and chemical processes that occurred in the early solar system and represent some of the oldest solid materials currently available for laboratory analyses. The delivery of organic matter by extraterrestrial material to the early Earth could have been an important source of complex prebiotic organic molecules available for the emergence of life. Analyses of primitive carbonaceous chondrites over the last five decades have revealed a major insoluble organic component [1,2], as well as a complex and highly diverse suite of soluble organic molecules of prebiotic importance [3,4] that includes carboxylic acids, N-heterocycles, sugars, amino acids, amines, and many other organic molecules that have not yet been identified [5]. Amino acids continue to be a primary focus of many soluble organic analyses in carbonaceous chondrites because (1) these molecules are essential components of life (as the monomers of proteins), (2) they have structural diversity (multiple possible isomers) that can be used to help constrain formation mechanisms and parent body conditions, and (3) most amino acids identified in carbonaceous chondrites are chiral, a property that can be used to distinguish between amino acids of extraterrestrial and terrestrial origins. The degree of parent body hydrothermal alteration has been shown to have a major influence on the formation and destruction of amino acids in carbonaceous meteorites as observed in the measured abundances and molecular distributions [6]. Aqueous alteration in primitive asteroids could have also led to the preferential enrichment of some left-handed amino acids over their right-handed forms, an astounding discovery that suggests that the origin of life on Earth or elsewhere was biased toward left-handed amino acid homochirality [7,8]. This talk will give an overview of what is known about the amino acid composition of carbonaceous chondrites, present some key unanswered questions, and discuss how the analysis of samples returned from asteroids Ryugu and Bennu will further advance our understanding of parent body chemistry and potential contributions from carbonaceous asteroids to the origin of life on Earth or elsewhere.

Daniel P. Glavin↗
NASA NTRS2014

Modeling and Prediction of the Noise from Non-Axisymmetric Jets

The new source model was combined with the original sound propagation model developed for rectangular jets to produce a new version of the rectangular jet noise prediction code. This code was validated using a set of rectangular nozzles whose geometries were specified by NASA. Nozzles of aspect ratios two, four and eight were studied at jet exit Mach numbers of 0.5, 0.7 and 0.9, for a total of nine cases. Reynolds-averaged Navier-Stokes solutions for these jets were provided to the contactor for use as input to the code. Quantitative comparisons of the predicted azimuthal and polar directivity of the acoustic spectrum were made with experimental data provided by NASA. The results of these comparisons, along with a documentation of the propagation and source models, were reported in a journal article publication (Ref. 4). The complete set of computer codes and computational modules that make up the prediction scheme, along with a user's guide describing their use and example test cases, was provided to NASA as a deliverable of this task. The use of conformal mapping, along with simplified modeling of the mean flow field, for noise propagation modeling was explored for other nozzle geometries, to support the task milestone of developing methods which are applicable to other geometries and flow conditions of interest to NASA. A model to represent twin round jets using this approach was formulated and implemented. A general approach to solving the equations governing sound propagation in a locally parallel nonaxisymmetric jet was developed and implemented, in aid of the tasks and milestones charged with selecting more exact numerical methods for modeling sound propagation, and developing methods that have application to other nozzle geometries. The method is based on expansion of both the mean-flowdependent coefficients in the governing equation and the Green's function in series of orthogonal functions. The method was coded and tested on two analytically prescribed mean flows which were meant to represent noise reduction concepts being considered by NASA. Testing (Ref. 5) showed that the method was feasible for the types of mean flows of interest in jet noise applications. Subsequently, this method was further developed to allow use of mean flow profiles obtained from a Reynolds-averaged Navier-Stokes (RANS) solution of the flow. Preliminary testing of the generalized code was among the last tasks completed under this contract. The stringent noise-reduction goals of NASA's Fundamental Aeronautics Program suggest that, in addition to potentially complex exhaust nozzle geometries, next generation aircraft will also involve tighter integration of the engine with the airframe. Therefore, noise generated and propagated by jet flows in the vicinity of solid surfaces is expected to be quite significant, and reduced-order noise prediction tools will be needed that can deal with such geometries. One important source of noise is that generated by the interaction of a turbulent jet with the edge of a solid surface (edge noise). Such noise is generated, for example, by the passing of the engine exhaust over a shielding surface, such as a wing. Work under this task supported an effort to develop a RANS-based prediction code for edge noise based on an extension of the classical Rapid Distortion Theory (RDT) to transversely sheared base flows (Refs. 6 and 7). The RDT-based theoretical analysis was applied to the generic problem of a turbulent jet interacting with the trailing edge of a flat plate. A code was written to evaluate the formula derived for the spectrum of the noise produced by this interaction and results were compared with data taken at NASA Glenn for a variety of jet/plate configurations and flow conditions (Ref. 8). A longer-term goal of this task was to work toward the development of a high-fidelity model of sound propagation in spatially developing non-axisymmetric jets using direct numerical methods for solving the relevant equations. Working with NASA Glenn Acoustics Branch personnel, numerical methods and boundary conditions appropriate for use in a high-resolution calculation of the full equations governing sound propagation in a steady base flow were identified. Computer codes were then written (by NASA) and tested (by OAI) for an increasingly complex set of flow conditions to validate the methods. The NASA-supplied codes were ported to the High-End Computing resources of the NASA Advanced Supercomputing facility for testing and validation against analytical (where possible) and independent numerical solutions. The cases which were completed during the course of this contract were solutions of the two-dimensional linearized Euler equations with no mean flow, a uniform mean flow and a nonuniform mean flow representative of a parallel flow jet.

Leib, Stewart J.↗
NASA NTRS1998

A Geometry Based Infra-Structure for Computational Analysis and Design

The computational steps traditionally taken for most engineering analysis suites (computational fluid dynamics (CFD), structural analysis, heat transfer and etc.) are: (1) Surface Generation -- usually by employing a Computer Assisted Design (CAD) system; (2) Grid Generation -- preparing the volume for the simulation; (3) Flow Solver -- producing the results at the specified operational point; (4) Post-processing Visualization -- interactively attempting to understand the results. For structural analysis, integrated systems can be obtained from a number of commercial vendors. These vendors couple directly to a number of CAD systems and are executed from within the CAD Graphical User Interface (GUI). It should be noted that the structural analysis problem is more tractable than CFD; there are fewer mesh topologies used and the grids are not as fine (this problem space does not have the length scaling issues of fluids). For CFD, these steps have worked well in the past for simple steady-state simulations at the expense of much user interaction. The data was transmitted between phases via files. In most cases, the output from a CAD system could go to Initial Graphics Exchange Specification (IGES) or Standard Exchange Program (STEP) files. The output from Grid Generators and Solvers do not really have standards though there are a couple of file formats that can be used for a subset of the gridding (i.e. PLOT3D data formats). The user would have to patch up the data or translate from one format to another to move to the next step. Sometimes this could take days. Specifically the problems with this procedure are:(1) File based -- Information flows from one step to the next via data files with formats specified for that procedure. File standards, when they exist, are wholly inadequate. For example, geometry from CAD systems (transmitted via IGES files) is defined as disjoint surfaces and curves (as well as masses of other information of no interest for the Grid Generator). This is particularly onerous for modern CAD systems based on solid modeling. The part was a proper solid and in the translation to IGES has lost this important characteristic. STEP is another standard for CAD data that exists and supports the concept of a solid. The problem with STEP is that a solid modeling geometry kernel is required to query and manipulate the data within this type of file. (2) 'Good' Geometry. A bottleneck in getting results from a solver is the construction of proper geometry to be fed to the grid generator. With 'good' geometry a grid can be constructed in tens of minutes (even with a complex configuration) using unstructured techniques. Adroit multi-block methods are not far behind. This means that a million node steady-state solution can be computed on the order of hours (using current high performance computers) starting from this 'good' geometry. Unfortunately, the geometry usually transmitted from the CAD system is not 'good' in the grid generator sense. The grid generator needs smooth closed solid geometry. It can take a week (or more) of interaction with the CAD output (sometimes by hand) before the process can begin. One way Communication. (3) One-way Communication -- All information travels on from one phase to the next. This makes procedures like node adaptation difficult when attempting to add or move nodes that sit on bounding surfaces (when the actual surface data has been lost after the grid generation phase). Until this process can be automated, more complex problems such as multi-disciplinary analysis or using the above procedure for design becomes prohibitive. There is also no way to easily deal with this system in a modular manner. One can only replace the grid generator, for example, if the software reads and writes the same files. Instead of the serial approach to analysis as described above, CAPRI takes a geometry centric approach. This makes the actual geometry (not a discretized version) accessible to all phases of the analysis. The connection to the geometry is made through an Application Programming Interface (API) and NOT a file system. This API isolates the top-level applications (grid generators, solvers and visualization components) from the geometry engine. Also this allows the replacement of one geometry kernel with another, without effecting these top-level applications. For example, if UniGraphics is used as the CAD package then Parasolid (UG's own geometry engine) can be used for all geometric queries so that no solid geometry information is lost in a translation. This is much better than STEP because when the data is queried, the same software is executed as used in the CAD system. Therefore, one analyzes the exact part that is in the CAD system. CAPRI uses the same idea as the commercial structural analysis codes but does not specify control. Software components of the CAD system are used, but the analysis suite, not the CAD operator, specifies the control of the software session. This also means that the license issues (may be) minimized and individuals need not have to know how to operate a CAD system in order to run the suite.

Haimes, Robert↗
NASA NTRS1990

Evaluation of thermal sprayed metallic coatings for use on the structures at Launch Complex 39

The current status of the evaluation program is presented. The objective was to evaluate the applicability of Thermal Sprayed Coatings (TSC) to protect the structures in the high temperature acid environment produced by exhaust of the Solid Rocket Boosters during the launches of the Shuttle Transportation System. Only the relatively low cost aluminum TSC which provides some cathodic protection for steel appears to be a practical candidate for further investigation.

Welch, Peter J.↗
NASA NTRS1991

Optical constants of solid methane and ethane from 10,000 to 450/cm

Near- and mid-IR spectra of thin films of crystalling phase I and phase II C2H6 are presented using a combined least squares and Kramers-Kronig analysis. Complex refractive indices derived from these data are also presented. To obtain material in phase I, samples are annealed at 33 K for about 30 min; phase II is obtained by recooling below the transition temperature of 20.4 K. The derived optical parameters are shown. The infrared spectrum of phase I CH4 exhibits broad structureless absorptions at about 1300 and 2600/cm. On cooling the sample below 20.4 K (phase II), the absorptions are sharpened, and each band develops fine structure. The present results and those of Roux et al. (1979) are compared. The agreement with the real parts is found to be excellent; given the difference in resolution, the agreement with the imaginary parts is also good.

Pearl, J.↗
NASA NTRS1970

Synthesis of diamonds

Shock wave transmitted through a solid exponential horn generates heat and pressure to convert part of a charge of graphite to diamonds. The shock wave is generated in the apparatus by a complex of magnetic fields and eddy currents.

Estes, M. F.↗
NASA NTRS1977

The photometric functions of Phobos and Deimos. III - Surface photometry of Phobos

Mariner 9 television pictures of Phobos are used to study the uniformity of a certain photometric scattering parameter over the surface of the satellite, assuming that the scattering law for Phobos can be represented by the Hapke-Irvine equation. Ways of avoiding topographically irregular areas are discussed, phase functions for Phobos are obtained from scans along the photometric equator, and the photometric behavior of selected areas not along this equator is examined. Searches are conducted for anomalously bright areas and evidence of solid rock on the surface. The results indicate that: (1) at least three large regions on the surface of Phobos are covered by a dark material of complex texture which scatters light according to the Hapke-Irvine law; (2) the average intrinsic phase coefficient of this material is 0.020 mag/deg over the phase-angle range from 20 to 80 deg; (3) even the topographically irregular areas have photometric properties similar to those of the three smooth regions; (4) the surface of Phobos is rougher than that of Deimos on the largest scale; and (5) apparent bright patches are most likely caused by local tilts of the surface.

Noland, M.↗
NASA NTRS1980

Analysis of pressure spectra measurements in a ducted combustion system

Combustion noise propagation in an operating ducted liquid fuel combustion system is studied in relation to the development of combustion noise prediction and suppression techniques. The presence of combustor emissions in the duct is proposed as the primary mechanism producing the attenuation and dispersion of combustion noise propagating in an operating liquid fuel combustion system. First, a complex mathematical model for calculating attenuation and dispersion taking into account mass transfer, heat transfer, and viscosity effects due to the presence of liquid fuel droplets or solid soot particles is discussed. Next, a simpler single parameter model for calculating pressure auto-spectra and cross-spectra which takes into account dispersion and attenuation due to heat transfer between solid soot particles and air is developed. Then, auto-spectra and cross-spectra obtained from internal pressure measurements in a combustion system consisting of a J-47 combustor can, a spool piece, and a long duct are presented. Last, analytical results obtained with the single parameter model are compared with the experimental measurements. The single parameter model results are shown to be in excellent agreement with the measurements.

Miles, J. H.↗
NASA NTRS2013

NASA-USRP Summer 2013 Internship Final Report

Three major projects were undertaken during the Summer 2013 USRP Internship: (A) assisting the cTAPS group with component and pressure vessel system analyses and documentation, (B) designing a hoisting fixture for a solid rocket motor, (C) finding an alternative to removing the DOT rated gaseous nitrogen tank from the roof for hydrostatic testing. Hypergolic Material Assessments (HMAs) and pressure calculations were performed on components of pressure systems. Additionally, component information was logged in the Standard Parts Database to provide a location where system designers can find information regarding components, including their specifications and compatibility with fluids. A hoisting fixture was designed to hoist a solid rocket motor and meets the specifications related to stress and size. However, there are issues with the fixtures bolt head allotment, the bolt spacing, and the complexity of the part. Finally, calculations were performed on an expiring DOT rated gaseous nitrogen tank in an attempt to re-rate it per ASME standards. This was unsuccessful so other options are being explored for the tank. While much progress was made on all three projects, there is still work to be performed on each project to achieve the desired results.

Gurganus, S. Christine↗
NASA NTRS2015

Organic Aerosol Volatility Parameterizations and Their Impact on Atmospheric Composition and Climate

Despite their importance and ubiquity in the atmosphere, organic aerosols are still very poorly parameterized in global models. This can be explained by two reasons: first, a very large number of unconstrained parameters are involved in accurate parameterizations, and second, a detailed description of semi-volatile organics is computationally very expensive. Even organic aerosol properties that are known to play a major role in the atmosphere, namely volatility and aging, are poorly resolved in global models, if at all. Studies with different models and different parameterizations have not been conclusive on whether the additional complexity improves model simulations, but the added diversity of the different host models used adds an unnecessary degree of variability in the evaluation of results that obscures solid conclusions.

Volatility↗