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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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NASA NTRSDate not supplied

AM Powder Flowability Capabilities at NASA Marshall Space Flight Center (MSFC)

Additive Manufacturing (AM) powder flowability is critical to metal 3D printing, because the more fluid the powder is, the better powder spreads. The NASA MSFC’s Contamination Control Team (CCT) studies density, flow, particle size distribution, and morphology for programs such as Moon-to-Mars Planetary Autonomous Construction Technology (MMPACT), ASTM Proficiency Testing for AM and Powder Metallurgy, and MSFC’s AM team. Examining and measuring powder characteristics is essential for improving flowability of AM powder and ensuring lot-to-lot consistency, which will help to prevent defects in manufactured parts. The CCT uses several methods to characterize AM powder. Optical particle size distribution and morphology analyses determine particle parameters including size, circularity, convexity, and dimensions. The Carney and Hall Flowmeter Funnel measures time it takes powder to flow through a funnel to compare relative flowability (free-flowing and non-free-flowing). In addition to this, the device utilizes a density cup which determines apparent density. Lastly, the Revolution Powder Analyzer measures dynamic powder flowability and behavior over time via digital imaging. Using the CCT’s lab, the team has produced ASTM Powder Proficiency Testing results with flow rates, apparent density, particle size distribution, and tap density on titanium-based and nickel-based powder and compared data with other companies/labs. Morphology data was also collected for various regolith simulant powder for the MMPACT program. Lastly, the CCT used morphology data to examine the flowability of Inconel 718 powder for Selective Laser Melting (SLM) and Directed Energy Deposition (DED) printers at MSFC. The CCT’s essential work in studying and enabling AM powder characterization has helped and will continue to help study new and refined powders in the AM industry.

Additive Manufacturing↗
NASA NTRSDate not supplied

AM Powder Flowability Capabilities at NASA Marshall Space Flight Center (MSFC)

Additive Manufacturing (AM) powder flowability is critical to metal 3D printing, because the more fluid the powder is, the better powder spreads. AM Powder Flowability Capabilities at NASA MSFC studies density, flow, particle size distribution, and morphology for programs such as Moon-to-Mars Planetary Autonomous Construction Technology (MMPACT), ASTM Proficiency Testing for AM and Powder Metallurgy, and MSFC’s AM team. Examining and measuring powder characteristics is essential for improving flowability of AM powder and ensuring lot-to-lot consistency, which will help to prevent defects in manufactured parts. The Contamination Control Team (CCT) uses several methods to characterize AM powder. Optical particle size distribution and morphology analyses determine particle parameters including size, circularity, convexity, and dimensions. The Carney and Hall Flowmeter Funnel measures time it takes powder to flow through a funnel to compare relative flowability (free-flowing and non-free-flowing). In addition to this, the device utilizes a density cup which determines apparent density. Lastly, the Revolution Powder Analyzer measures dynamic powder flowability and behavior over time via digital imaging. Using the CCT’s lab, the team has produced ASTM Powder Proficiency Testing results with flow rates, apparent density, particle size distribution, and tap density on titanium-based and nickel-based powder and compared data with other companies/labs. Morphology data was also collected for various regolith simulant powder for the MMPACT program. Lastly, the CCT used morphology data to examine the flowability of Inconel 718 powder for Selective Laser Melting (SLM) and Directed Energy Deposition (DED) printers at MSFC. The CCT’s essential work in studying and enabling AM powder characterization has helped and will continue to help study new and refined powders in the AM industry.

Additive Manufacturing↗
NASA NTRS1988

Microgravity two-phase fluid flow pattern modeling

When gas and liquid mixtures flow in a pipe, the distribution of the two phases may take many forms. A flow pattern, or flow regime, is the characteristic spatial distribution of the phases of flow in a pipe. Because heat transfer and pressure drop are dependent on the characteristic distribution of phases, it is necessary to describe flow patterns in an appropriate manner so that a hydrodynamic or heat transfer theory applicable to that can be chosen. A theoretical two phase flow regime transition map under a microgravity environment was developed on physical concepts. These transitions use four basic flow patterns: dispersed flow, slug flow, stratified flow, and annular flow. The forces considered are body force, surface tension force, inertial force, friction, and the force from eddy turbulent fluctuation. Three dimensionless parameters were developed. Because these transition boundaries were developed based on physical concepts, they should be applicable to flow regimes occurring in various design conditions. Because the flow pattern data from KC-135 experiments are insufficient to verify these theoretical transition lines completely, an adiabatic experiment for flow regime analysis is recommended.

Lee, Doojeong↗
NASA NTRS1987

The effect of eddy distribution on momentum and heat transfer near the wall in turbulent pipe flow

A study was conducted to determine the effect of eddy distribution on momentum and heat transfer near the wall in turbulent pipe flow. The buffer zone was of particular interest in that it is perhaps the most complicated and least understood region in the turbulent flow field. Six eddy diffusivity relationships are directly compared on their ability to predict mean velocity and temperature distributions in turbulent air flow through a cylindrical, smooth-walled pipe with uniform heat transfer. Turbulent flow theory and the development of the eddy diffusivity relationships are briefly reviewed. Velocity and temperature distributions derived from the eddy diffusivity relationships are compared to experimental data for fully-developed pipe flow in turbulent air at a Prandtl number of 0.73 and Reynolds numbers ranging from 8100 to 25 000.

Zurawski, Robert L.↗
NASA NTRS1982

An assessment of a modified potential flow code for calculating the effect of small geometric change on the pressure and forces of supercritical airfoils

Wind-tunnel test data for two closely related supercritical airfoils were compared with calculations obtained from a nonconservative, potential flow code over a Mach number range from 0.20 to 0.80. The potential flow code includes an iterated, integral boundary-layer correction. The theoretical pressure distributions correlated more closely with the experimental pressure distributions when the flow was entirely subsonic or subsonic with a small supersonic zone than when the flow contained a large supersonic zone. The predicted drag level was below the experimental values at nearly all test conditions and the difference in drag level for the two airfoils was not accurately predicted.

Hicks, R. M.↗
NASA NTRS1984

Modification to the NASA Langley 4- by 7-meter tunnel for improved rotorcraft aerodynamics and acoustics

Investigations have been conducted with the aim of improving circuit mean flow characteristics and test section turbulence intensity in the NASA Langley 4 x 7-m wind tunnel. Flow deflectors were instaled to displace the airstream and provide more symmetrical velocity distributions. The periodic flow pulsations of the open test section configuration were addressed by modifications of either the test section entrance, using triangular vanes, or the test section exit, using an alternative flow collector geometry; the latter proved more effective.

Applin, Z. T.↗
NASA NTRS1975

Pressure distribution in a converging-diverging nozzle during two-phase choked flow of subcooled nitrogen

Choked flow rates and axial pressure distributions were measured for subcooled nitrogen in a converging-diverging nozzle with a constant area section in the throat region. Stagnation pressures ranged from slightly above saturation to twice the thermodynamic critical pressure. Stagnation temperatures ranged from 0.75 to 1.03 times the thermodynamic critical temperature. The choking plane appears to be at the divergence end of the constant area throat section. At high stagnation pressures the fluid appears to stay liquid well into the constant area throat region; however, at near saturation stagnation pressures it appears that vaporization occurs at or before the entrance to the constant area throat region. The throat-to-stagnation pressure ratio data exhibits an anomalous flat region. This anomaly appears to be fundamentally related to the two-phase process and not merely to the present specific nozzle geometry. The fluid appears to be metastably all liquid below the saturation pressure. The data are compared to various flow models. No model adequately describes the whole range of the experiment.

Simoneau, R. J.↗
NASA NTRS1975

Investigation of the unsteady pressure distribution on the blade of an axial flow fan

A major source of the noise generated by high bypass ratio aircraft fan engines is the unsteady pressures (forces and moments) acting on the fan blades. These unsteady pressures are the result of the interaction of the blades with the wakes of upstream blade rows, inlet flow distortions, and inlet turbulence. An experimental system was developed which will permit the measurement of the unsteady pressure distributions; a series of experiments were conducted to investigate these effects, and the results are compared with predictions from existing theoretical analyses.

Henderson, R. E.↗
NASA NTRS1970

Method of calculating blade-to-blade plane flow in centrifugal pump

Steam filament solution determines velocity distribution due to potential flow in the blade-to-blade plane of the radial impeller. This is used to determine the mass-averaged relative fluid angle, which is in turn used in an axisymmetric program to obtain steam surfaces of the assumed axisymmetric flow.

Jackson, E. D.↗
NASA NTRS1975

Pressure distribution in a converging-diverging nozzle during two-phase choked flow of subcooled nitrogen

Choked flow rates and axial pressure distributions were measured for subcooled nitrogen in a converging-diverging nozzle with a constant area section in the throat region. Stagnation pressures ranged from slightly above saturation to twice the thermodynamic critical pressure. Stagnation temperatures ranged from 0.75 to 1.03 times the thermodynamic critical temperature. The choking plane is at the divergence end of the constant area throat section. At high stagnation pressures the fluid stays liquid well into the constant area throat region; at near saturation stagnation pressures it appears that vaporization occurs at or before the entrance to the constant area throat region. The throat-to-stagnation pressure ratio data exhibits an anomalous flat region, and this anomaly is related to the two-phase process. The fluid is metastably all liquid below the saturation pressure.

Simoneau, R. J.↗
NASA NTRS1988

Implications of large flow velocity signatures in nearly isotropic ion distributions

ISEE-1 energetic ion distributions are compared with previously published lower-energy ISEE-1 H(+) and He(2+) distributions in the quiet-time plasma sheet at about 15 earth radii and within about 1 earth radius of the expected neutral sheet position. Although moment calculations performed over the nearly isotropic H(+) and He(2+) plasma distributions yield low bulk velocities of less than 14 km/s, the spectral shapes of these signatures are indicative of high flow speeds. It is suggested that H(+) and H(2+) ions of solar wind origin were accelerated through an electrostatic potential of about 2.4 kV prior to the ISEE-1 observations in the plasma sheet on a closed magnetospheric field line, and that a second plasma sheet population existed at this ISEE-1 position in the geomagnetic field.

Williams, D. J.↗
NASA NTRS1994

Observations of nonadiabatic acceleration of ions in Earth's magnetotail

We present observations of the three-dimensional velocity distributions of protons in the energy range 20 eV to 52 keV at locations within and near the current sheet of Earth's magnetotail at geocentric radial distances 35 to 87 R(sub E). These measurements were acquired on December 8, 1990, with a set of electrostatic analyzers on board the Galileo spacecraft during its approach to Earth in order to obtain one of its gravitational assists to Jupiter. It is found that the velocity distributions are inadequately described as quasi-Maxwellian distributions such as those found in the central plasma sheet at positions nearer to Earth. Instead the proton velocity distributions can be categorized into two major types. The first type is the 'lima bean' shaped distribution with high-speed bulk flows and high temperatures that are similar to those found nearer to Earth in the plasma sheet boundary layer. The second type consists of colder protons with considerably lesser bulk flow speeds. Examples of velocity distributions are given for the plasma mantle, a region near the magnetic neutral line, positions earthward and tailward of the neutral line, and the plasma sheet boundary layer. At positions near the neutral line, only complex velocity distributions consisting of the colder protons are found, whereas both of the above types of distributions are found in and near the current sheet at earthward and tailward locations. Bulk flows are directed generally earthward and tailward at positions earthward and tailward of the neutral line, respectively. Only the high-speed, hot distribution is present in the plasma sheet boundary layer. The observations are interpreted in terms of the nonadiabatic acceleration of protons that flow into the current sheet from the plasma mantle. For this interpretation the hot, 'lima bean' shaped distributions are associated with meandering, or Speiser, orbits in the current sheet. It is suggested that the colder, lower-speed proton velocity distributions are the result of fractional or few gyromotions before ejection out of the current sheet, but this speculation must be further investigated with appropriate kinetic simulation of trajectories.

Frank, L. A.↗