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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 955 records · Page 53

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NASA NTRS1977

Convection of viscous fluids: Energetics, self-similarity, experiments, geophysical applications and analogies

The main results were the formulas for the mean convection velocities, of a viscous fluid and for the mean temperature difference in the bulk of the convecting fluid. These were obtained: by scaling analysis of the Boussinesq equations, by analysis of the energetics of the process, and by using similarity and dimensional arguments. The last approach defines the criteria of similarity and allows the proposition of some self-similarity hypotheses. By several simple new ways, an expression for the efficiency coefficient gamma of the thermal convection was also obtained. An analogy is pointed out between non-turbulent convection of a viscous fluid and the structure of turbulence for scales less than Kolmogorov's internal viscous microscale of turbulence.

Golitsyn, G. S.↗

NASA NTRS1978

Effect of hydraulic fluid (MIL-H-83282) on selected commercial O-ring compounds

Acrylonitrile and fluorocarbon compounds were evaluated at various temperatures and time intervals in samples of the fluid obtained from three qualified suppliers. It was concluded that both polymers can function in hydraulic fluids within the conditions defined by this study. Hydraulic fluid from each manufacturer was similar in its effect upon each given O-ring material, with one exception. Similarly, there were no striking differences in the resistance of O-rings of the same generic rubber type when provided by the different manufacturers.

Wood, T. E.↗

NASA NTRS1978

Solar heat transport fluid

The progress made on the development and delivery of noncorrosive fluid subsystems is reported. These subsystems are to be compatible with closed-loop solar heating or combined heating and hot water systems. They are also to be compatible with both metallic and non-metallic plumbing systems. At least 100 gallons of each type of fluid recommended by the contractor will be delivered under the contract. The performance testing of a number of fluids is described.

Source record↗

NASA NTRS1978

Filling of orbital fluid management systems

A study was performed with three objectives: (1) analyze fluid management system fill under orbital conditions; (2) determine what experimentation is needed; and (3) develop an experimental program. The fluid management system was a 1.06m (41.7 in) diameter pressure vessel with screen channel device. Analyses were conducted using liquid hydrogen and N2O4. The influence of helium and autogenous pressurization systems was considered. Analyses showed that fluid management system fill will be more difficult with a cryogen than with an earth storable. The key to a successful fill with cryogens is in devising techniques for filling without vent liquid, and removing trapped vapor from the screen device at tank fill completion. This will be accomplished with prechill, fill, and vapor condensation processes. Refill will require a vent and purge process, to dilute the residual helium, prior to introducing liquid. Neither prechill, chill, nor purge processes will be required for earth storables.

Merino, F.↗

NASA NTRS1979

A zero G fluid drop injector for the drop dynamics module spacelab experiment

A fluid drop injector was developed to form and release fluid drops into free drift within an experimental apparatus known as the Drop Dynamics Module which is to be flown on an earth orbiting Spacelab. To verify the design concept, a breadboard injector was flown on the NASA KC-135 zero g airplane after which more extensive laboratory 1 g tests were performed to improve the injector design and enable it to meet the module's functional requirements. The breadboard fluid drop injector will be modified and upgraded to flight hardware.

Holtz, G. M.↗

NASA NTRS1979

Turbulent vortices in stratified fluids

In the present paper, calculations, made with the finite difference axisymmetric WAKE computer code, of the influence of turbulence and stratification on the behavior of vortex rings are compared with experimental data. Calculations, made with the two-dimensional version of the code, are used to study the behavior of vortex pairs in stably stratified atmospheres for a range of Froude numbers. Stratification is shown to have a profound effect on the radius of a vortex ring descending into a stably stratified fluid. The separation of the vortices of a vortex pair remains nearly constant or decreases monotonically with increasing penetration of a stably stratified fluid, depending on whether the stratification is discontinuous or linear. An analysis based on an energy balance is used to assess the maximum descent of a vortex pair in a stably stratified fluid.

Hecht, A. M.↗

NASA NTRS1979

Effects of hydraulic fluid CVCM on silver-Teflon

Changes in the solar absorptance of silver-Teflon (Ag/FEP) surfaces were measured after contamination by the outgassing products of hydraulic fluid and irradiation by solar simulators. Although radiator surfaces are selected for stability to the solar ultraviolet and particulate environment, contaminant deposition and their interaction with solar exposure can degrade their performance. The test procedure to deposit the hydraulic fluid collected volatile condensible material (CVCM), irradiate, and determine solar absorptance changes by reflectance measurements using a spectrophotometer and a solar simulator is described. The tests showed that for the estimated deposition rates on the Ag/FEP, the hydraulic fluid CVCM fraction remaining under normal conditions (above -40 C) would not degrade its performance. The residual CVCM can be easily removed from Ag/FEP by wiping with a solvent saturated flannel. The changes in solar absorptance with the CVCM film thickness and the radiation exposure duration are reported, concluding that vacuum ultraviolet radiation did not prevent easy removal of CVCM.

Muscari, J. A.↗

NASA NTRS1979

Origin of longitudinal grooving in Tiu Vallis, Mars - Isolation of responsible fluid-types

Fluid instability analysis developed for the growth or decay of large, longitudinal roller vortex perturbations imposed at the base of fluids of exponentially stratified viscosities is presented. The origin of longitudinal grooving and fluting in a region of converging flow in Tiu Vallis, Mars, is analyzed, and the propensity of fluids, such as water, mudflow/debris flow, and lava, to develop longitudinal roll patterns as part of their flow field is tested. It is found that the grooving pattern in Tiu Vallis was probably formed by vortex motion in a mudflow or debris-laden slurry, but exact representation of sediment/debris concentration or sediment transport machanism is not yet possible. It is concluded that longitudinal vortex motion modelled in this analysis can develop in water, lava, or ice, but that the specific flow characteristics of these models which include the vortex motion are unreasonable for flow in Tiu Vallis.

Thompson, D. E.↗

NASA NTRS1980

Two-phase working fluids for the temperature range of 50 to 350 deg, phase 2

Several two phase heat transfer fluids were tested in aluminum and carbon steel reflux capsules for over 25,000 hours at temperatures up to 300 C. Several fluids showed very good stability and would be useful for long duration heat transfer applications over the range 100 to 350 C. Instrumentation for the measurement of surface tension and viscosity were constructed for use with heat transfer fluids over the temperature range 0 to 300 C and with pressures from 0 to 10 atmospheres. The surface tension measuring device constructed requires less than a 1.0 cc sample and displays an accuracy of about 5 percent in preliminary tests, while the viscometer constructed for this program requires a 0.05 cc sample and shows an accuracy of about 5 percent in initial tests.

Saaski, E. W.↗

NASA NTRS1979

Geophysical fluid flow experiment

The essential fluid flow processes associated with the solar and Jovian atmospheres will be examined in a laboratory experiment scheduled for performance on Spacelab Missions One and Three. The experimental instrumentation required to generate and to record convective fluid flow is described. Details of the optical system configuration, the lens design, and the optical coatings are described. Measurement of thermal gradient fields by schlieren techniques and measurement of fluid flow velocity fields by photochromic dye tracers is achieved with a common optical system which utilizes photographic film for data recording. Generation of the photochromic dye tracers is described, and data annotation of experimental parameters on the film record is discussed.

Broome, B. G.↗

NASA NTRS1980

Spectroscopic study of the effect on an EHD contact of trichloroethane addition to a traction fluid

Addition of trichloroethane to a traction fluid was studied in a ball/diamond plate EHD apparatus by infrared emission spectroscopy of the radiation transmitted through the plate. Small concentrations of an organic chloride at first increased infrared radiance, then decreased it. Large concentrations caused a rapid decrease. During running, the infrared spectrum showed an increase of aromatics and olefins. A polymeric deposit formed on the plate. X-ray examination of the ball surface showed the presence of chlorine. Reuse of the same ball with fresh fluid resulted in similar chain of events, indicating that adsorbed chloride could promote fluid deterioration.

Lauer, J. L.↗

NASA NTRS1980

Measurement of velocity fields in fluid dynamics experiments

A microcomputer-video system was used to measure both spatial and temporal variations of two dimensional fluid flow velocity fields. The system utilizes two methods: the first method is the traditional one in which tracers are introduced into the fluid and their position compared at two closely spaced times; and the second method involves scattering coherent light in the fluid and obtaining motion by analyzing the multiple exposed speckle pattern recorded on photographic film.

Fitzjarrald, D. E.↗

NASA NTRS1980

Formulation and evaluation of C-Ether fluids as lubricants useful to 260 C

Three base stocks were evaluated in bench and bearing tests to determine their suitability for use at bulk oil temperatures (BOT) from -40 C to +260 C. A polyol ester gave good bearing tests at a bulk temperature of 218 C, but only a partially successful run at 274 C. These results bracket the fluid's maximum operating temperature between these values. An extensive screening program selected lubrication additives for a C-ether (modified polyphenyl ether) base stock. One formulation lubricated a bearing for 111 hours at 274 C (BOT), but this fluid gave many deposit related problems. Other C-ether blends produced cage wear or fatigue failures. Studies of a third fluid, a C-ether/disiloxane blend, consisted of bench oxidation and lubrication tests. These showed that some additives react differently in the blend than in pure C-ethers.

Clark, F. S.↗

NASA NTRS1980

Micro-fluid exchange coupling apparatus

In a macro-fluid exchange, a hollow needle, such as a syringe needle, is provided for penetrating the fluid conduit of the animal. The syringe needle is coupled to a plenum chamber having an inlet and outlet port. The plenum chamber is coupled to the syringe needle via the intermediary of a standard quick disconnect coupling fitting. The plenum chamber is carried at the end of a drive rod which is coupled to a micrometer drive head. The micrometer drive head is slidably and pivotably coupled to a pedestal for adjusting the height and angle of inclination of the needle relative to a reference base support. The needle is positioned adjacent to the incised trachea or a blood vessel of a small animal and the micrometer drive head is operated for penetrating the fluid conduit of the animal.

Johnson, J. E., Jr.↗

NASA NTRS1980

Laser beam manifold and particle photography system for use in fluid velocity measurements

A laser beam manifold and particle photography system has been developed for use in fluid velocity measurements. The laser manifold is a device which transforms a single laser beam into several uniform parallel beams. By orienting two manifolds mutually perpendicular, an optical grid can be formed which acts as a reference for fluid velocity measurements. This optical grid is for all practical purposes totally nonperturbing to the flow. Tracer particles moving in the plane of the grid are then photographed to yield fluid velocities that can be measured relative to the optical grid. System construction and theory are presented.

Owen, R. B.↗

NASA NTRS1981

Effect of the fluid core on changes in the length of day due to long period tides

The long period luni-solar tidal potential is known to cause periodic changes in the earth's rotation rate. It is found that the effect of a dissipationless fluid outer core is to reduce the amplitudes of these tidal perturbations by about 11 percent. When the fluid core effect is added to Agnew and Farrell's (1978) estimate of the effect of an equilibrium ocean, the result is in accord with observation. The effects of dissipative processes within the fluid core are also examined. Out-of-phase perturbations are found which could be as large as about 10 ms at 18.6 yr. It is concluded, however, that the poorly understood decade fluctuations in the earth's rotation rate will prohibit observation of this effect.

Wahr, J. M.↗

NASA NTRS1982

Improved perfect-fluid energy-momentum tensor with spin in Einstein-Cartan space-time

The description of the spin given here is classical in that it is intrinsic but not quantized. The approach in this matter is similar to, for example, the work of Bailey and Israel (1973, 1975, 1979), where the fluid particles, which have intrinsic spin, may be galaxies or clusters of galaxies. The elementary particles of these objects and the 'ferromagnetic alignment' of their quantum spins are not resorted to in order to describe a fluid with spin. Physically this means that the equation of motion for the spin tensor is a modified Fermi-Walker transport equation (Misner et al., 1973), arising as a direct result of the inclusion of spin as an intrinsic variable in the thermodynamic description of the internal energy. The variables in this description are classical variables throughout and are not microscopic fields. An improved perfect-fluid energy-momentum tensor that includes spin and torsion is presented. Use is made of a Lagrangian variational principle based on the tetrad formalism of Halbwach (1960) and the method od constraints of Ray (1972).

Ray, J. R.↗

NASA NTRS1982

Measurement of interstage fluid-annulus dynamical properties

The work described in this paper is part of an Electric Power Research Institute sponsored effort to improve rotor vibrational performance on power plant feed water pumps. A major objective of this effort is to reduce vibration levels by devising inter-stage sealing configurations with optimized damping capacity, realizing that the typical multi-stage centrifugal pump has several ore inter-stage fluid annuli than it has journal bearings. Also, the fluid annuli are distributed between the journal bearings where vibration levels are highest and can therefore be 'exercised' more as dampers than can the bearings. Described in this paper is a test apparatus which has been built to experimentally determine fluid-annulus dynamical coefficients for various configurations of inter-stage sealing geometry.

Adams, M. L.↗