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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 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
NASA NTRS1980

An investigation of the motion of small particles as related to the formulation of zero gravity experiments

The nature of Brownian motion and historical theoretical investigations of the phenomemon are reviewed. The feasibility of using a laser anemometer to perform small particle experiments in an orbiting space laboratory was investigated using latex particles suspended in water in a plastic container. The optical equipment and the particle Doppler analysis processor are described. The values of the standard deviation obtained for the latex particle motion experiment were significantly large compared to corresponding velocity, therefore, their accuracy was suspect and no attempt was made to draw meaningful conclusions from the results.

Sastry, V. S.↗
NASA NTRS1985

Seeding subsonic, transonic and supersonic flows with 0.5 micron polystyrene spheres

Polystyrene latex particles have been successfully used as laser velocimetry seed material for flows in the Ames High Reynolds Channels (HR) 1 and 2, the pilot channel, and the one-foot low speed tunnel. These facilities provide test flows with Mach numbers from 0.1 to 3.0 and test section sizes from 4 inches by 6 inches to 18 inches by 24 inches. Tunnel mass flow in the HR-2 channel can approach 1000 lb/sec. The latex particles have the following favorable characteristics: size of 0.35 to 0.55 microns diameter; spherical shape; specific gravity of 1.05; excellent flow trackability; low toxicity; and low cost. they have the disadvantage of being packaged as an aqueous suspension which must be diluted and introduced into the test flow as an atomized mist. This must occur sufficiently far upstream of the test section to minimize flow disturbances and permit the liquid mist to evaporate before reaching the model. Several techniques which have been developed to accomplish satisfactory seeding will be described.

Seegmiller, H. L.↗
NASA NTRS1987

Preparation of polystyrene microspheres for laser velocimetry in wind tunnels

Laser Velocimetry (L/V) had made great strides in replacing intrusive devices for wind tunnel flow measurements. The weakness of the L/V has not been the L/V itself, but proper size seeding particles having known drag characteristics. For many Langley Wind Tunnel applications commercial polystyrene latex microspheres suspended in ethanol, injected through a fluid nozzle provides excellent seeding but was not used due to the high cost. This paper provides the instructions, procedures, and formulations for producing polystyrene latex monodisperse microspheres of 0.6, 1.0, 1.7, 2.0, and 2.7 micron diameters. These are presently being used at Langley Research Center as L/V seeding particles.

Nichols, Cecil E., Jr.↗
NASA NTRS1986

Development and testing of a space-flight dilatometer/reactor

A stainless-steel piston cylinder dilatometer (volume about 100 cu cm), designed for use in microgravity, was tested and modified for the purpose of obtaining the polymerization kinetics of monodisperse polystyrene latexes, as well as the latexes themselves. A low-speed, oscillatory agitation (10 rpm, 30 deg of arc/per cycle) and redesigned stir paddle were selected for the low shear requirements of the microgravity experiments. Conversion histories accurate to within 2 percent were obtained after apparatus modification and procedural changes were implemented.

Sudol, E. D.↗
NASA NTRS1990

Measuring Monodisperse Small Particles En Masse

New optical method enables determination of sizes of approximately-micron-sized particles. Arrays of particles act as diffraction gratings. Simple and inexpensive apparatus replaces high-magnification microscopes in measurements of diameters of small polystyrene latex spheres. Device being used to determine monodispersity and diameters of polystyrene latex microspheres used as seeding material for laser-velocimetry flow measurements in NASA's wind tunnels. Characterization of particle sizes important in wide range of fields, including manufacture of plastics and ceramics, biochemistry, and medicine.

Bruce, Robert A.↗
NASA NTRS1990

Fine-tuning of process conditions to improve product uniformity of polystyrene particles used for wind tunnel velocimetry

Monodisperse polymer particles (having uniform diameter) were used for the last two decades in physical, biological, and chemical sciences. In NASA Langley Research Center monodisperse polystyrene particles are used in wind tunnel laser velocimeters. These polystyrene (PS) particles in latex form were formulated at the Engineering Laboratory of FENGD using emulsion-free emulsion polymerization. Monodisperse PS latices particles having different particle diameters were formulated and useful experimental data involving effects of process conditions on particle size were accumulated. However, similar process conditions and chemical recipes for polymerization of styrene monomer have often yielded monodisperse particles having varying diameters. The purpose was to improve the PS latex product uniformity by fine-tuning the process parameters based on the knowledge of suspension and emulsion polymerization.

Ray, Asit K.↗
NASA NTRS1991

A fiber-optic probe for particle sizing in concentrated suspensions

A fiber-optic probe employing two monomode optical fibers, one for transmitting a Gaussian laser beam to the scattering volume and the second, positioned at some backscatter angle, for receiving the scattered light is described. Performance and suitability of the system for a process control environment is assessed by studying a suspension of polystyrene latex particles over a wide range of sizes and concentrations. The results show that the probe is ideal for a process control environment in industrial and laboratory applications. Particle size is recovered, without any additional corrections for multiple light scattering, in concentrations containing up to 10 percent solids of 39-nm polystyrene latex spheres.

Dhadwal, Harbans S.↗
NASA NTRS1994

Electronic Engineering Notebook: A software environment for research execution, documentation and dissemination

The electronic engineering notebook (EEN) consists of a free form research notebook, implemented in a commercial package for distributed hypermedia, which includes utilities for graphics capture, formatting and display of LaTex constructs, and interfaces to the host operating system. The latter capability consists of an information computer-aided software engineering (CASE) tool and a means to associate executable scripts with source objects. The EEN runs on Sun and HP workstations. The EEN, in day-to-day use can be used in much the same manner as the sort of research notes most researchers keep during development of projects. Graphics can be pasted in, equations can be entered via LaTex, etc. In addition, the fact that the EEN is hypermedia permits easy management of 'context', e.g., derivations and data can contain easily formed links to other supporting derivations and data. The CASE tool also permits development and maintenance of source code directly in the notebook, with access to its derivations and data.

Moerder, Dan↗
NASA NTRS2013

Radiative Transfer Theory Verified by Controlled Laboratory Experiments

We report the results of high-accuracy controlled laboratory measurements of the Stokes reflection matrix for suspensions of submicrometer-sized latex particles in water and compare them with the results of a numerically exact computer solution of the vector radiative transfer equation (VRTE). The quantitative performance of the VRTE is monitored by increasing the volume packing density of the latex particles from 2 to 10. Our results indicate that the VRTE can be applied safely to random particulate media with packing densities up to 2. VRTE results for packing densities of the order of 5 should be taken with caution, whereas the polarized bidirectional reflectivity of suspensions with larger packing densities cannot be accurately predicted. We demonstrate that a simple modification of the phase matrix entering the VRTE based on the so-called static structure factor can be a promising remedy that deserves further examination.

Radiative transfer↗
NASA NTRS1971

Nonflammable organic-base paint for oxygen-rich atmospheres

New paint formulations, which combine aqueous latex paints with inorganic pigments and additives, produce coatings that are self-extinguishing in pure oxygen at pressures up to twice the partial pressure of atmospheric oxygen. A paint formulation in percent by weight is given and the properties of resultant coatings are discussed.

Harwell, R. J.↗
NASA NTRS1973

Fire retardant cellulosic foam

Method mixture of cyanamide, phosphoric acid, and monobasic ammonium phosphates for preliminary treatment of paper. Papier-mache, in second step, is pulped in water and latex is added. Urea formaldehyde solution mixed to maximize foaming and resin dispersion is added. Mixture is then cast within 30 to 60 seconds and dried twice.

Luttinger, M.↗
NASA NTRS1974

Nonflammable coating compositions

Nonflammable coating compositions are described for use in high-oxygen environments which include an aqueous suspension of synthetic mica, an alkali metal silicate gelant and a waterbase latex resin emulsion. Inorganic white and/or color pigments and additives such as glass microballoons are employed to provide a wide range of colors and optical properties.

Krupnick, A. C.↗
NASA NTRS1973

Experimental test of plant canopy reflectance models on cotton

Spectroradiometric data on the bidirectional reflectance function was collected for a cotton canopy as a function of observer zenith angle, observer angle, and solar zenith angle. The area under study was about 40 miles from the Gulf of Mexico and the prevailing winds blew inland such that cloud formation increased during the day. The standard reflectance panel was constructed of plywood that had been spray painted with a flat white latex paint. Physical and optical plant parameters were measured. A time lapse mechanism was constructed to operate a 16 mm movie camera such that single frames could be exposed at intervals of one per second up to one per hour. Data were digitized from a strip chart recorder and reflectance panel measurements.

Lemaster, E. W.↗
NASA NTRS1974

Effects of viscoelasticity on cavitation in drag reducing fluids

To study cavitation inception in polymer solutions, a blow-down water tunnel with short running times was used. Tests were made using 1/4 and 1/2 inch diameter models of hemispherical-nose cylinders. To accurately detect the inception of cavitation, a reliable technique was developed using a continuously operating He-Ne gas laser. The laser beam was adjusted to grazing incidence with the model at the minimum pressure point where cavitation inception was to be expected. A sensitive photocell was placed at ninety degrees to detect the beam. As incipient cavitation occurred, the bubbles caused scattering of the laser beam which was picked up by the photocell. Static pressure near the model in the working section of the tunnel was measured using a solid-state pressure pick-up. The signals from the photocell and the pressure pick-up were recorded on an oscillograph. Velocity field visualization was achieved using one microsecond duration light pulses scattered by small polystryrene latex spheres in the flow.

Ting, R. Y.↗
NASA NTRS1974

Feasibility study for the manufacture of zero gravity pharmaceuticles, immunological, and viral agents

The feasibility of extracting, isolating, purifying, separating, or preparing medical and biological products of high socio-economic value in space was studied. In particular, the study was designed to concentrate on the isolation or purification of virals, pharmaceutical and immunological agents by means of electrophoresis, as the Apollo 16 flight demonstrated that a mixed population of latex spheres (.2 and .8 microns) could be successfully separated by electrophoresis in space and without sedimentation with minimal convection. This prompted NASA scientists to look into the possibility of carrying out types of biochemical experiments that would utilize space for medical purposes.

Source record↗
NASA NTRS1974

Multichannel forward scattering meter for oceanography

An instrument was designed and built that measures the light scattered at several angles in the forward direction simultaneously. The instrument relies on an optical multiplexing technique for frequency encoding of the different channels suitable for detection by a single photodetector. A Mie theory computer program was used to calculate the theoretical volume scattering function for a suspension of polystyrene latex spheres. The agreement between the theoretical and experimental volume scattering functions is taken as a verification of the calibration technique used.

Mccluney, W. R.↗