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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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Stability characteristics of two degree of freedom gyroscope having hydrodynamic grooved journal rotor bearings, discussing frequency of self excited oscillation
Hydrodynamic model of blood coagulation in stagnation point flow, analyzing platelet diffusion, white cell bonding stress and thrombus formation
Three dimensional unsteady and steady sediment distribution obtained by Monte Carlo simulation method, using stochastic hydrodynamics model for transport
Stellar hydrodynamic equations for thin disk galaxy derived from collisionless Boltzmann equation moments
General relativistic hydrodynamics near equilibrium, discussing velocity and kinetic energy increase spherically symmetric large masses as function of radius change
Squeeze film lubrication for gyroscope wheels and behavior of hydrodynamic spiral grooved spin axis bearing
Water-lubricated three-lobe hydrodynamic journal bearing stability tests at zero load with and without axial grooves
Mathematical model for solving hydrodynamic flow equations in nonhomogenous magnetic field for plasma flow along field line in presence of gravitational field
Performance tests of water-lubricated, Rayleigh step, hydrodynamic journal bearings under no load conditions to determine stability
Poincare hydrodynamic analogy in celestial mechanics, relating differential equations for dynamic systems with two degrees of freedom and two and three dimensional flow
Steam turbine blade metal removal rates by repetitive water drop impact, using hydrodynamic model
Collisionless ion exosphere kinetic and hydrodynamic models comparison for polar wind supersonic flow characteristics
Hydrodynamic journal bearing stability tests were conducted with 1.5 in. diameter, 1.5 in. long fixed geometry bearings in water at 80 F with zero load. Five fixed geometry bearings were rated in order of diminishing stability as follows: (1) three-tilted-lobe bearing (offset factor of 1.0), (2) herringbone-groove bearing, (3) one-segment, three-pod, shrouded Rayleigh-step bearing, (4) three-tilted-lobe journal with axial grooves (offset factor of 1.0) mated with a plain bearing, and (5) three-centrally-lobed bearing with axial grooves (offset factor of 0.5). The various parameters that affect the stability of each bearing configuration were investigated.
We have used a fully implicit, Lagrangian, hydrodynamic computer code incorporating a nuclear reaction network to follow thermonuclear runaways in the hydrogen-rich envelopes of white dwarfs in order to produce a nova outburst. Because of the short time-scales and the high nuclear burning rates produced in our models, the nuclear reactions are far out of equilibrium and the beta-plus unstable nuclei become the most abundant nuclei in the envelope except for hydrogen and helium. Our models have ejected 1.00017 solar mass with kinetic energies of 8 times 10 to the 44-th power ergs, a value that agrees quite closely with the observed values for novae.
Self-acting and hydrodynamic seals are described. The analytical procedures are outlined for obtaining a seal force balance and the operating film thickness. Particular attention is given to primary ring response (seal vibration) to rotating seat face runout. This response analysis revealed three different vibration modes. Proposed applications of self-acting seals in gas turbine engines and in rocket vehicle turbopumps are described. Also experimental data on self-acting face seals operating under simulated gas turbine conditions are given; these data show the feasibility of operating the seal at conditions of 345 newtons per square centimeter (500 psi) and 152 meters per second (500 ft/sec) sliding speed.
The hydrodynamic theory of the extreme pool boiling heat fluxes is expanded to embrace a variety of problems that have not previously been analyzed. These problems include the prediction of the peak heat flux on a variety of finite heaters, the influence of viscosity on the Taylor and Helmoltz instability mechanisms with application to film boiling and to the peak heat flux in viscous liquids, the formalization of the analogy between high-current-density electrolysis and boiling, and the description of boiling in the low-gravity limit. The predictions are verified with a large number of new data.
Previous theoretical models are considered, giving attention to the original formulation proposed by Zuber (1959), an infinite horizontal flat plate, a horizontal cylinder, and a sphere. Some general features of any hydrodynamic prediction are inferred by examining the characteristics of the models. It is found possible to eliminate the need for observed values of the vapor-blanket thickness. The concepts obtained are utilized in the derivation of expressions for the prediction of the peak pool-boiling heat flux in the case of some new configurations.
Self-acting and hydrodynamic seals are described. The analytical procedures are outlined for obtaining a seal force balance and the operating film thickness. Particular attention is given to primary ring response (seal vibration) to rotating seat face runout. This response analysis revealed three different vibration modes. Proposed applications of self-acting seals in gas turbine engines and in rocket vehicle turbopumps are described. Also experimental data on self-acting face seals operating under simulated gas turbine conditions are given; these data show the feasibility of operating the seal at conditions of 345 newtons per square centimeter (500 psi) and 152 meters per second (500 ft/sec) sliding speed.