A two-dimensional analysis of laser heat addition in a constant absorptivity gas
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Molvik, G. A.↗
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SSME fuelside preburner two-dimensional analysis
The flow field within the fuelside preburner of the Space Shuttle Main Engine is calculated using a reacting flow code (REACT2D). Inlet and modeling parameters involved in the numerical calculation are systematically varied to establish the sensitivity of the calculated exit temperature profile. It is found that differences in the inlet equivalence ratio have a large effect on the turbine inlet temperature profile. A variety of preburner inlet modeling changes such as inlet turbulence level, modeling the gases as burned, unburned, premixed, or unmixed, are shown to have a smaller effect on the calculated turbine inlet temperature profile. Also, the form of finite differencing used is shown to have an effect on the temperature profile.
Vanoverbeke, T. J.↗
Three-dimensional analysis of potential vorticity associated with tropopause folds and observed variations of ozone and carbon monoxide
The usability and reliability of potential vorticity as a meteorological stratospheric tracer are evaluated. The concept of potential vorticity conservation during transport in which stratospheric and tropospheric air are mixing is tested. Aircraft data collected on April 20, 1984 in the western and southwestern U.S. are analyzed in order to derive potential vorticity data; vertical cross sections of constant-pressure data and temperature and wind speed gradients are examined. The tropopause fold observed during the April 20, 1984 aircraft flights is described. The potential vorticity, ozone mixing ratio, and carbon monoxide mixing ratio are compared; a positive correlation between potential vorticity and the ozone mixing ratio and a negative correlation between the potential vorticity and the carbon monoxide mixing ratio are detected. The data support the concepts of the conservation of potential vorticity, the entrainment and mixing of tropospheric air across the boundaries of the fold, and the applicability of potential vorticity as a stratospheric tracer.
Danielsen, Edwin F.↗
Quasi-Three-Dimensional Analysis Of Turbine Flow
Computer program reduces computer time and treats multiple elements. Improved design-analysis program for turbomachinery applied to multiple turbine elements simultaneously. Enables continuous and coherent analyses rather than previous piece-meal analyses of flow fields. Effects of upstream elements on downstream flow taken into account automatically.
Hsu, Wayne W.↗
Three-dimensional analysis of surface crack-Hertzian stress field interaction
The results are presented of a stress intensity factor analysis of semicircular surface cracks in the inner raceway of an engine bearing. The loading consists of a moving spherical Hertzian contact load and an axial stress due to rotation and shrink fit. A 3-D linear elastic Boundary Element Method code was developed to perform the stress analysis. The element library includes linear and quadratic isoparametric surface elements. Singular quarter point elements were employed to capture the square root displacement variation and the inverse square root stress singularity along the crack front. The program also possesses the capability to separate the whole domain into two subregions. This procedure enables one to solve nonsymmetric fracture mechanics problems without having to separate the crack surfaces a priori. A wide range of configuration parameters was investigated. The ratio of crack depth to bearing thickness was varied from one-sixtieth to one-fifth for several different locations of the Hertzian load. The stress intensity factors for several crack inclinations were also investigated. The results demonstrate the efficiency and accuracy of the Boundary Element Method. Moreover, the results can provide the basis for crack growth calculations and fatigue life prediction.
Ballarini, R.↗
Two-dimensional analysis of two-phase reacting flow in a firing direct-injection diesel engine
The flow field, spray penetration, and combustion in two-stroke diesel engines are described. Fuel injection begins at 345 degrees after top dead center (ATDC) and n-dodecane is used as the liquid fuel. Arrhenius kinetics is used to calculate the reaction rate term in the quasi-global combustion model. When the temperature, fuel, and oxygen mass fraction are within suitable flammability limits, combustion begins spontaneously. No spark is necessary to ignite a localized high temperature region. Compression is sufficient to increase the gaseous phase temperature to a point where spontaneous chemical reactions occur. Results are described for a swirl angle of 22.5 degrees.
Nguyen, H. Lee↗
One-dimensional analysis of plane and radial thin film flows including solid-body rotation
The flow of a thin liquid film with a free surface along a horizontal plate which emanates from a pressurized vessel is examined by integrating the equations of motion across the thin liquid layer and discretizing the integrated equations using finite difference techniques. The effects of 0-g and solid-body rotation will be discussed. The two cases of interest are plane flow and radial flow. In plane flow, the liquid is considered to be flowing along a channel with no change in the width of the channel, whereas in radial flow the liquid spreads out radially over a disk, so that the area changes along the radius. It is desired to determine the height of the liquid film at any location along the plate of disk, so that the heat transfer from the plate or disk can be found. The possibility that the flow could encounter a hydraulic jump is accounted for.
Thomas, S.↗
One-dimensional analysis of the hydrodynamic and thermal characteristics of thin film flows including the hydraulic jump and rotation
The flow of a thin liquid film with a free surface along a horizontal plane that emanates from a pressurized vessel is examined numerically. In one g, a hydraulic jump was predicted in both plane and radial flow, which could be forced away from the inlet by increasing the inlet Froude number or Reynolds number. In zero g, the hydraulic jump was not predicted. The effect of solid-body rotation for radial flow in one g was to 'wash out' the hydraulic jump and to decrease the film height on the disk. The liquid film heights under one g and zero g were equal under solid-body rotation because the effect of centrifugal force was much greater than that of the gravitational force. The heat transfer to a film on a rotating disk was predicted to be greater than that of a stationary disk because the liquid film is extremely thin and is moving with a very high velocity.
Thomas, S.↗
Performance of supersonic axial-flow compressors based on one-dimensional analysis
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Wright, Linwood C↗
One-dimensional analysis of choked-flow turbines
Turbines for most applications requiring high work output per stage have one or more blade rows which are choked. This analysis indicated that the area ratios and equivalent blade speed are the controlling factors in the design and operation of such turbines. Six criteria are stated that will aid in establishing from test data of multistage turbines which blade rows are choked and which are not. The variation in internal flow conditions with operating conditions for a turbine equipped with an adjustable stator is determined for one application of stator adjustment.
English, Robert E↗
Dimensional analysis of acoustically propagated signals
Traditionally, long term measurements of atmospherically propagated sound signals have consisted of time series of multiminute averages. Only recently have continuous measurements with temporal resolution corresponding to turbulent time scales been available. With modern digital data acquisition systems we now have the capability to simultaneously record both acoustical and meteorological parameters with sufficient temporal resolution to allow us to examine in detail relationships between fluctuating sound and the meteorological variables, particularly wind and temperature, which locally determine the acoustic refractive index. The atmospheric acoustic propagation medium can be treated as a nonlinear dynamical system, a kind of signal processor whose innards depend on thermodynamic and turbulent processes in the atmosphere. The atmosphere is an inherently nonlinear dynamical system. In fact one simple model of atmospheric convection, the Lorenz system, may well be the most widely studied of all dynamical systems. In this paper we report some results of our having applied methods used to characterize nonlinear dynamical systems to study the characteristics of acoustical signals propagated through the atmosphere. For example, we investigate whether or not it is possible to parameterize signal fluctuations in terms of fractal dimensions. For time series one such parameter is the limit capacity dimension. Nicolis and Nicolis were among the first to use the kind of methods we have to study the properties of low dimension global attractors.
Hansen, Scott D.↗
A Three-Dimensional Analysis of the Galactic Gamma-Ray Emission Resulting from Cosmic-Ray Interaction with the Interstellar Gas and Radiation Fields
This final report outlines the progress of the contractor's support for the analysis of data under ADP (NRA 96-ADP-08; Proposal No. 167-96 adp). The primary task object was to construct a 3-D model for the distribution of high-energy (20 MeV-30 GeV) gamma-ray emission in the Galactic disk. Under this task the contractor was to utilize data from the EGRET instrument on the Compton Gamma-Ray Observatory, HI and CO surveys, radio-continuum surveys at 408 MHz, 1420 MHz, 5 GHz, and 19 GHz, the COBE Diffuse Infrared Background Experiment (DIRBE) all-sky maps from I to 240 um, and ground-based B,V, J, H and K photometry. The respective contributions to the high-latitude gamma-ray emission from cosmic ray-matter interactions, inverse Compton scattering, and extra-galactic emission were to be determined.
Sodraski, Thomas J.↗
A Three-Dimensional Analysis of the Galactic Gamma-Ray Emission Resulting from Cosmic-Ray Interactions with the Interstellar Gas and Radiation Fields
The primary task objective is to construct a 3-D model for the distribution of high-energy (20 MeV - 30 GeV) gamma-ray emission in the Galactic disk. Under this task the contractor will utilize data from the EGRET instrument on the Compton Gamma-Ray Observatory, H I and CO surveys, radio-continuum surveys at 408 MHz, 1420 MHz, 5 GHz, and 19 GHz, the COBE Diffuse Infrared Background Experiment (DIRBE) all-sky maps from 1 to 240 microns, and ground-based B, V, J, H, and K photometry. The respective contributions to the gamma-ray emission from cosmic ray/matter interactions, inverse Compton scattering, and extragalactic emission will be determined.
Sodroski, Thomas J.↗
Tidal Disruption of Strengthless Rubble Piles: A Dimensional Analysis
A relatively simple prescription for estimating the number of debris clumps (n) that form after a catastrophic tidal disruption event is presented. Following the breakup event, it is assumed that the individual debris particles follow keplerian orbits about the planet until the debris' gravitational contraction timescale (t(sub c)) becomes shorter than its orbital spreading timescale (t(sub s)). When the two timescales become comparable, self-gravity breaks up the debris train into n = L/D clumps, which is the debris length/diameter ratio at that instant. The clumps subsequently orbit the planet independent of each other. The predicted number of clumps n is in good agreement with more sophisticated N-body treatments of tidal breakup for parabolic encounters, and the dependence of n upon the progenitor's density as well as its orbit is also mapped out for hyperbolic encounters. These findings may be used to further constrain both the orbits and densities of the tidally disrupted bodies that struck Callisto and Ganymede. A cursory analysis shows that the Gomul and Gipul crater chains on Callisto, which have the greatest number of craters among the known chains, were formed by projectiles having comet-like densities estimated at rho(sub o) < 1 gm/cc.
Hahn, Joseph M.↗
A 3-Dimensional Analysis of the Galactic Gamma-Ray Emission Resulting from Cosmic-Ray Interactions with the Interstellar Gas and Radiation Fields
The contractor will provide support for the analysis of data under ADP (NRA 96-ADP- 09; Proposal No . 167-96adp). The primary task objective is to construct a 3-D model for the distribution of high-energy (20 MeV - 30 GeV) gamma-ray emission in the Galactic disk. Under this task the contractor will utilize data from the EGRET instrument on the Compton Gamma-Ray Observatory, H I and CO surveys, radio-continuum surveys at 408 MHz, 1420 MHz, 5 GHz, and 19 GHz, the COBE Diffuse Infrared Background Experiment (DIME) all-sky maps from 1 to 240 p, and ground-based B, V, J, H, and K photometry. The respective contributions to the gamma-ray emission from cosmic ray/matter interactions, inverse Compton scattering, and extragalactic emission will be determined.
Sodroski, Thomas J.↗
A new light on caloric test--what was disclosed by three dimensional analysis of caloric nystagmus?
For better understanding of caloric nystagmus, this phenomenon will be reviewed historically in three stages. 1) The first light on caloric nystagmus was thrown by Barany 1906. Through direct observation of eye movements, Barany established the caloric test as an important tool to determine the side of lesion for vertigo. 2) The second light is shed by electrooculogram (EOG) from the late 1950th. EOG enabled qualitative analysis of caloric nystagmus, and proved Barany's convection theory, but resulted in neglect of vertical and roll eye movements. 3) The third light is gained by 3D recording of eye movements started from the late 1980th. 3D recordings of eye movements enabled us to analyze the spatial orientation of caloric nystagmus, and disclose the close correlation of the nystagmus components in the head vertical and the space vertical planes, suggesting a contribution of the velocity storage integrator. The 3D property of caloric nystagmus will be explained in detail.
Caloric Tests/history↗
Transient Three-Dimensional Analysis of Nozzle Side Load in Regeneratively Cooled Engines
Nozzle side loads are potentially detrimental to the integrity and life of almost all launch vehicles. the lack of a detailed prediction capability results in reducing life and increased weight for reusable nozzle systems. A clear understanding of the mechanism that contribute to side loads during engine startup, shutdown, and steady-state operations must be established. A CFD based predictive tool must be developed to aid the understanding of side load physics and development of future reusable engine.
ng, Ten-See↗
Multiphysics Modeling for Dimensional Analysis of a Self-Heated Molten Regolith Electrolysis Reactor for Oxygen and Metals Production on the Moon and Mars
The technology of direct electrolysis of molten lunar regolith to produce oxygen and molten metal alloys has progressed greatly in the last few years. The development of long-lasting inert anodes and cathode designs as well as techniques for the removal of molten products from the reactor has been demonstrated. The containment of chemically aggressive oxide and metal melts is very difficult at the operating temperatures ca. 1600 C. Containing the molten oxides in a regolith shell can solve this technical issue and can be achieved by designing a self-heating reactor in which the electrolytic currents generate enough Joule heat to create a molten bath.
Dominguez, Jesus↗