Properties of the clouds of Venus
Method for calculating properties of monochromatic radiation through layer of dispersed particles and its application to Venus clouds
CLOUD PHYSICS↗
SEARCH · Engineering Papers
Results for “Particle dispersion”
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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Research on Mechanisms of Alloy Strengthening Semiannual Report
Alloy strengthening by fine oxide particle dispersions, and splat cooling process for alloy development
METALLURGY↗
Pressure wave generation in particle-fueled combustion systems. I - Parametric study.
Generation of pressure wave by explosion of condensed phase fuel particles dispersed in gaseous oxidizer
COMBUSTION WAVE↗
Research on mechanisms of alloy strengthening Semiannual report
Fine oxide particle dispersion strengthened alloy structures and mechanical properties and splat cooling process for alloy development
METAL OXIDE↗
Research on mechanisms of alloy strengthening Semiannual report
Alloy strengthening by fine oxide particle dispersions, and splat cooling process for alloy development
Grant, N. J.↗
The effect of solute additions on the steady-state creep behavior of dispersion-strengthened aluminum.
The effect of solute additions on the steady-state creep behavior of coarse-grained dispersion-strengthened aluminum alloys was studied. Recrystallized dispersion-strengthened solid solutions were found to have stress and temperature sensitivities quite unlike those observed in single-phase solid solutions having the same composition and grain size. The addition of magnesium or copper to the matrix of a recrystallized dispersion-strengthened aluminum causes a decrease in the steady-state creep rate which is much smaller than that caused by similar amounts of solute in single-phase solid solutions. All alloys exhibited essentially a 4.0 power stress exponent in agreement with the model of Ansell and Weertman. The activation energy for steady-state creep in dispersion-strengthened Al-Mg alloys, as well as the stress dependence, was in agreement with the physical model of dislocation climb over the dispersed particles.
Reynolds, G. H.↗
Elevated temperature deformation of TD-nickel.
Sensitivity of the elevated temperature (above 0.5 Tm) deformation of TD-nickel to grain size and shape was examined in both tension and creep. Elevated temperature strength increased with increasing grain diameter and increasing L/D ratio. Temperature sensitivity of the yield stress, as well as high (compared to self diffusion) apparent tensile activation enthalpies were the result of the internal stress not being proportional to the shear modulus. Creep activation enthalpies increased with increasing L/D ratio and, to a lesser extent, increasing grain diameter, reaching high values which may be apparent values. The thoria particle dispersion may have been altered by elevated temperature tensile and creep deformation.
Petrovic, J. J.↗
Atmospheric transformation of solar radiation reflected from the ocean
Airborne measurements of the brightness spectrum of the Atlantic Ocean in the wavelength region from 0.4 to 0.7 micron are analyzed. These measurements were made over a tropical region of the Atlantic from an aircraft at heights of 0.3 and 10.5 km during the TROPEX-72 experiment. The results are used to estimate the contribution of the atmosphere to the overall brightness of the ocean-atmosphere system. It is concluded that: (1) the atmosphere decreases the absolute brightness of the ocean by a factor of 5 to 10 and also strongly affects the spectral behavior of solar radiation reflected from the ocean surface; (2) the atmospheric contribution to overall brightness may vary considerably under real conditions; (3) finely dispersed particles and Rayleigh scattering affect the spectral distribution of solar radiation; and (4) the spectral composition of ocean-atmosphere brightness may be completely governed by the atmosphere.
Malkevich, M. S.↗
High temperature resistant cermet and ceramic compositions
High temperature oxidation resistance, high hardness and high abrasion and wear resistance are properties of cermet compositions particularly to provide high temperature resistant refractory coatings on metal substrates, for use as electrical insulation seals for thermionic converters. The compositions comprise a sintered body of particles of a high temperature resistant metal or metal alloy, preferably molybdenum or tungsten particles, dispersed in and bonded to a solid solution formed of aluminum oxide and silicon nitride, and particularly a ternary solid solution formed of a mixture of aluminum oxide, silicon nitride and aluminum nitride. Ceramic compositions comprising a sintered solid solution of aluminum oxide, silicon nitride and aluminum nitride are also described.
Phillips, W. M.↗
High temperature resistant cermet and ceramic compositions
Cermet compositions having high temperature oxidation resistance, high hardness and high abrasion and wear resistance, and particularly adapted for production of high temperature resistant cermet insulator bodies are presented. The compositions are comprised of a sintered body of particles of a high temperature resistant metal or metal alloy, preferably molybdenum or tungsten particles, dispersed in and bonded to a solid solution formed of aluminum oxide and silicon nitride, and particularly a ternary solid solution formed of a mixture of aluminum oxide, silicon nitride and aluminum nitride. Also disclosed are novel ceramic compositions comprising a sintered solid solution of aluminum oxide, silicon nitride and aluminum nitride.
Phillips, W. M.↗
Post-Skylab activities
The Apollo Soyuz Test Program is described. A modification of the Skylab furnace was developed for the ASTP mission that had a maximum temperature of 1200 C, a programmed cool down to give more uniform growth rates, and a He quench system to shorten the time required to reach allowable touch temperature. The Space Processing Applications Rocket (SPAR) program was initiated to provide some continuity in flight experimentation. Liquid mixing, immiscible alloy solidification, composite materials, bubbles and dispersed particles during solidification, and containerless processing techniques were studied in the SPAR program.
Source record↗
Toughening of thermosetting polyimides
Work directed toward increasing the resistance to crack propagation of thermoset polyimides is described. Rubber modification and Teflon microfiber impregnation techniques for increasing fracture toughness are investigated. Unmodified Kerimid 601 has a fracture surface work value of 0.20 in-lbs/sq in. Dispersed particles of amine terminated butadiene acrylonitrile liquid rubber or of silicone rubber do not raise this value much. By contrast, 5 percent of well fibrillated Teflon produces an eight-fold increase in fracture toughness. Further process improvements should increase this factor to 20-30.
Gollob, D. S.↗
Material response from Mach 0.3 burner rig combustion of a coal-oil mixture
Wedge shaped specimens were exposed to the combustion gases of a Mach 0.3 burner rig fueled with a mixture of 40 weight percent micron size coal particles dispersed in No. 2 fuel oil. Exposure temperature was about 900 C and the test duration was about 44 one hour cycles. The alloys tested were the nickel base superalloys, IN-100, U-700 and IN-792, and the cobalt base superalloy, Mar-M509. The deposits on the specimens were analyzed and the extent of corrosion/erosion was measured. The chemical compositions of the deposits were compared with the predictions from an equilibrium thermodynamic analysis. The experimental results were in very good agreement with the predictions.
Santoro, G. J.↗
A theoretical and experimental study of turbulent particle-laden jets
Mean and fluctuating velocities of both phases, particle mass fluxes, particle size distributions in turbulent particle-laden jets were measured. The following models are considered: (1) a locally homogeneous flow (LHF) model, where slip between the phases was neglected; (2) a deterministic separated flow (DSF) model, where slip was considered but effects of particle dispersion by turbulence were ignored; and (3) a stochastic separated flow (SSF) model. The SSF model performed reasonably well with no modifications in the prescriptions for eddy properties from its original calibration. A modified k- model, incorporating direct contributions of interphase transport on turbulence properties (turbulence modulation), was developed within the framework of the SSF model.
Shuen, J. S.↗
Behaviors of Polymer Additives Under EHL and Influences of Interactions Between Additives on Friction Modification
Polymer additives have become requisite for the formulation of multigrade engine oils. The behavior of polymethacrylate (PMA)-thickened oils as lubricants in concentrated contacts under nominal rolling and pure sliding conditions was investigated by conventional optical interferometry. The PMA thickened oils behaved differently from the base oil in the formation of elastohydrodynamic (EHL) films. The higher the elastohydrodynamic molecular weight of the PMA contained in the lubricant, the thinner was the oil film under EHL conditions. The film thickness of shear-degraded PMA-thickened oils was also investigated. The behavior of graphite particles dispersed in both the base oil and the PMA-thickened oil was studied under pure sliding by taking photomicrographs. Many kinds of additives are contained in lubricating oil and the interactions between additives are considered. The interactions of zinc-organodithiophosphates (ZDP) with other additives is discussed.
Sakurai, T.↗
Ten past and ten future GAS/MAUS-payloads
MAUS (materials science autonomous experiments) is one out of a series of flight opportunities which the Space Program of West Germany offers to scientists from the disciplines of materials research and processing for performing materials science investigations under microgravity conditions. Up to now, ten MAUS experiments were flown which were dealing with the following scientific topics: decomposition of binary alloys with miscibility gap in the liquid state, interaction of a solidification front with dispersed particles, critical Marangoni number, investigation of the magnetic compound MnBi, shrinkage of gas bubbles in glass melts and slip casting. The ten future experiments are partly reflights with modification of the scientific objectives as well as new experiments in the fields of chemical reactions, heat transfer, glass technology and Ostwald ripening. Looking to ten flown payloads, the peculiarities of instrument technology in GAS-cans and its evolution is discussed with emphasis on structure, electronics and thermal design. A typical modern payload using 100 percent of the resource is presented.
Staniek, S.↗
Turbulence modeling of gas-solid suspension flows
The purpose here is to discuss and review advances in two-phase turbulent modeling techniques and their applications in various gas-solid suspension flow situations. In addition to the turbulence closures, heat transfer effect, particle dispersion and wall effects are partially covered.
Chen, C. P.↗
Modeling of confined turbulent fluid-particle flows using Eulerian and Lagrangian schemes
Two important aspects of fluid-particulate interaction in dilute gas-particle turbulent flows (the turbulent particle dispersion and the turbulence modulation effects) are addressed, using the Eulerian and Lagrangian modeling approaches to describe the particulate phase. Gradient-diffusion approximations are employed in the Eulerian formulation, while a stochastic procedure is utilized to simulate turbulent dispersion in the Lagrangina formulation. The k-epsilon turbulence model is used to characterize the time and length scales of the continuous phase turbulence. Models proposed for both schemes are used to predict turbulent fully-developed gas-solid vertical pipe flow with reasonable accuracy.
Adeniji-Fashola, A.↗