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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 1,009 records · Page 56
All sourcesNASA NTRSDOE OSTI
NASA NTRS1983

Lubrication of 35-millimeter-bore ball bearings of several designs to 2.5 million DN

Parametric tests were conducted with 35mm bore, angular contact ball bearings with either a single or double outer and guided cage. The bearings were either lubricated by oil jets or employed inner ring lubrication. Outer ring cooling was added in selected tests. Lubricant flow to the bearing ranged from 300 to 1900 cc/min. All bearings were successfully run at speeds to 2.5 million DN. Increasing the lubricant flow decreased bearing ring temperatures but increased bearing power lines. The power loss and race temperatures of a jet lubricated with double outer land guided cage were always higher than those of the single land guided design at similar test conditions. The lowest bearing operating temperatures were achieved when inner ring lubrication and outer ring cooling were combined. It is found that cage slip of a double outer land guided cage is approximately twice that of a single outer land guided cage.

Schuller, F. T.↗
DOE OSTI2025

A Novel Optical Instrument for On-Line Measurement of Particle Size Distribution—Application to Clean Coal Technologies

A flow cell is a critical measurement interface for many optical instruments. However, the flows are often sampled under harsh conditions, such as under high pressure and/or high temperature, in the presence of particles, moisture, vapors with high dew points or corrosive gases. Therefore, obtaining a high-optical-quality flow cell that does not perturb the measurement is a significant challenge. To address this challenge, we proposed a new flow cell that employs a unique laminar coaxial flow field (for the purge and sample flows). A test system was built to conduct particle size distribution (PSD) measurements with no sampling bias using a state-of-the-art analyzer (Malvern Panalytical Insitec). The results revealed that the measurement zone is well defined solely by the sample flow, and the optical windows are well protected by the purge flow, with minimal risk of any depositions from the sample flow. Using this flow cell, the Insitec can successfully measure PSD under high pressure and temperature under moist, corrosive conditions without generating any sampling bias. Importantly, we successfully applied this flow cell for on-line PSD measurement for the flue gas of a 100 kWth pressurized oxy-coal combustor operating at 15 bara.

Cheng, Mao (ORCID:0000000213273900)↗
NASA NTRS1991

The use of direct numerical simulation data in turbulence modeling

Direct numerical simulations (DNS) of turbulent flows provide a complete data base to develop and to test turbulence models. In this article, the progress made in developing models for the dissipation rate equation is reviewed. New scaling arguments for the various terms in the dissipation rate equation were tested using data from DNS of homogeneous shear flows. Modifications to the epsilon-equation model that take into account near-wall effects were developed using DNS of turbulent channel flows. Testing of new models for flows under mean compression was carried out using data from DNS of isotropically compressed turbulence. In all of these studies the data from the simulations was essential in guiding the model development. The next generation of DNS will be at higher Reynolds numbers, and will undoubtedly lead to improved models for computations of flows of practical interest.

Mansour, N. N.↗
DOE OSTI2020

Spent Crystalline Silicotitanate Storage Study

Washington River Protection Solutions is working to support initial production of immobilized low-activity waste (LAW) by feeding Hanford tank supernate from tank farms to the Hanford Waste Treatment and Immobilization Plant (WTP) LAW Facility. This goal incorporates the design of a Tank-Side Cesium Removal (TSCR) system, which filters tank waste supernate to remove suspended solids and then removes Cs by processing it through crystalline silicotitanate (CST) ion exchange media manufactured by Honeywell UOP, LLC. The 137 Cs-depleted product is intended to be sent to the WTP for vitrification. The Cs-loaded CST columns will be stored indefinitely, with a goal of eventual CST removal and treatment. Thus, the spent CST needs to be recoverable. The testing described herein looks to potential upset process conditions where CST storage may be required before various rinse steps are completed. This study evaluated upset conditions at three sequential processing steps envisioned for TSCR (feed, 0.1 M NaOH rinse, water rinse), and in-column drying with compressed air (normal end step) to assess impacts on the nature of the CST bed. Testing was conducted at the small scale (12-mL bed volume); simulated AP-105 tank waste was used as the feed. Following process disruption, the CST bed was dried in place at 70 °C. Post-dried CST bed physical properties (angle of repose, penetration depth, particle morphological changes) were measured to evaluate how CST moved and flowed. The testing is intended to provide a preliminary assessment of issues that may arise from desiccation of CST with the indicated salt solutions in place. Since these were small-scale tests, the processing conditions will not match full scale conditions exactly; however, the tests do provide insight into the impact of stopping processing at an earlier step than normal. Except for the feed that was dried in-place, all other process stop-conditions showed the CST bed flowed well after drying. At this small scale, CST beds would not present an issue for retrievability. The feed that was dried in place had solidified into a rock-hard monolith with no movement possible. Samples had to be chipped from the surface.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
NASA NTRS1976

Model investigation of inlet plenum flow straightening techniques for altitude test facility

An investigation was conducted to evaluate and improve the quality of the airflow to be supplied to the engine in altitude test chambers 3 and 4 of the Propulsion Systems Laboratory at the Lewis Research Center. One-twentieth-scale models of the inlet plenum chamber of the two test chambers were used in the investigation to minimize time and cost. It was possible to reduce the velocity spread in the inlet plenum from approximately 100 m/sec (330 ft/sec) to approximately 10 m/sec (30 ft/sec) through the combined use of flow diverters, multiple spaced screens, flow straighteners, and turning vanes.

Riddlebaugh, S. M.↗
NASA NTRS1988

NASA powered lift facility internally generated noise and its transmission to the acoustic far field

Noise tests of NASA Lewis Research Center's Powered Lift Facility (PLF) were performed to determine the frequency content of the internally generated noise that reaches the far field. The sources of the internally generated noise are the burner, elbows, valves, and flow turbulence. Tests over a range of nozzle pressure ratios from 1.2 to 3.5 using coherence analysis revealed that low frequency noise below 1200 Hz is transmitted through the nozzle. Broad banded peaks at 240 and 640 Hz were found in the transmitted noise. Aeroacoustic excitation effects are possible in this frequency range. The internal noise creates a noise floor that limits the amount of jet noise suppression that can be measured on the PLF and similar facilities.

Huff, Ronald G.↗
NASA NTRS1994

Numerical design of advanced multi-element airfoils

The current study extends the application of computational fluid dynamics to three-dimensional high-lift systems. Structured, overset grids are used in conjunction with an incompressible Navier-Stokes flow solver to investigate flow over a two-element high-lift configuration. The computations were run in a fully turbulent mode using the one-equation Baldwin-Barth turbulence model. The geometry consisted of an unswept wing which spanned a wind tunnel test section. Flows over full and half-span Fowler flap configurations were computed. Grid resolution issues were investigated in two dimensional studies of the flapped airfoil. Results of the full-span flap wing agreed well with experimental data and verified the method. Flow over the wing with the half-span was computed to investigate the details of the flow at the free edge of the flap. The results illustrated changes in flow streamlines, separation locations, and surface pressures due to the vortex shed from the flap edge.

Mathias, Donovan L.↗
NASA NTRS2007

Polymethylmethacrylate (PMMA) Material Test Results for the Capillary Flow Experiments (CFE)

In support of the Capillary Flow Experiments (CFE) program, several polymethylmethacrylate (PMMA) flight vessels were constructed. Some vessels used a multipiece design, which was chemically welded together. Due to questions regarding the effects of the experiment fluid (silicone oil) on the weld integrity, a series of tests were conducted to provide evidence of the adequacy of the current vessel design. Tensile tests were conducted on PMMA samples that were both in the as-received condition, and also aged in air or oil for up to 8 weeks. Both welded and unwelded samples were examined. Fracture of the joints was studied using notched tensile specimens and Brazilian disk tests. Results showed that aging had no effect on tensile properties. While the welded samples were weaker than the base parent material, the weld strength was found to be further degraded by bubbles in the weld zone. Finally a fracture analysis using the worst-case fracture conditions of the vessel was performed, and the vessel design was found to have a factor of three safety margin.

Lerch, Bradley A.↗
NASA NTRS1980

Full scale visualization of the wing tip vortices generated by a typical agricultural aircraft

The trajectories of the wing tip vortices of a typical agricultural aircraft were experimentally determined by flight test. A flow visualization method, similar to the vapor screen method used in wind tunnels, was used to obtain trajectory data for a range of flight speeds, airplane configurations, and wing loadings. Detailed measurements of the spanwise surface pressure distribution were made for all test points. Further, a powered 1/8 scale model of the aircraft was designed, built, and used to obtain tip vortex trajectory data under conditions similar to that of the full scale test. The effects of light wind on the vortices were demonstrated, and the interaction of the flap vortex and the tip vortex was clearly shown in photographs and plotted trajectory data.

Cross, E. J., Jr.↗
NASA NTRS1980

Full scale visualization of the wing tip vortices generated by a typical agricultural aircraft

The trajectories of the wing tip vortices of a typical agricultural aircraft were experimentally determined by flight test. A flow visualization method, similar to the vapor screen method used in wind tunnels, was used to obtain trajectory data for a range of flight speeds, airplane configurations, and wing loadings. Detailed measurements of the spanwise surface pressure distribution were made for all test points. Further, a powered 1/8 scale model of the aircraft was designed, built, and used to obtain tip vortex trajectory data under conditions similar to that of the full-scale test. The effects of light wind on the vortices were demonstrated, and the interaction of the flap vortex and the tip vortex was clearly shown in photographs and plotted trajectory data.

Cross, E. J., Jr.↗
NASA NTRS1984

Real-gas simulation for the Shuttle Orbiter and planetary entry configurations including flight results

By testing configurations in a gas (like CF4) which can produce high normal-shock density ratios, such as those encountered during hypersonic entry, certain aspects of real-gas effects can be simulated. Results from force-moment, shock-shape and oil flow visualization tests are presented for both the Shuttle Orbiter and a 45 deg sphere-cone in CF4 and air at M = 6, and comparisons are made with flight results. Pitching-moment coefficients measured on a Shuttle Orbiter model in CF4 showed a nose-up increment, compared with air results, that was almost identical to the difference between preflight predictions and flight in the high hypersonic regime. The drag coefficient measured in CF4 on the 45 deg sphere-cone, which is the same configuration used on the forebody of the Pioneer Venus entry vehicles, showed excellent agreement with flight data at M = 6.

Calloway, R. L.↗
NASA NTRSDate not supplied

Thermal Protection System P50 Cork Environments and Response due to Radiative Heating

Space Launch System (SLS) experienced deflagration of the acreage of the Core Stage base heat shield during the Green Run hot-fire test campaigns and Artemis I flight. The burning products from the base heat shield during Green Run hot-fire test operation led to concerns in aerothermal environments and thermal protection system (TPS) performance prior to Artemis I flight. This work documents a highly controlled ground test within the NASA Marshall Space Flight Center’s Nonmetallic Materials Branch thermal vacuum chamber (TVC) and investigates the P50 cork heat transfer environments and thermal protection system (TPS) response due to sensitivity changes in radiative heat rates, ambient pressure, air entrainment mass flow rates, test gas and TPS sample types. An SLS ascent ambient pressure profile was also simulated within the TVC facility. This test data enabled the efforts toward the Artemis I SLS post-flight reconstruction and initial assessment of flight TPS performance. A ground test program was developed to gain an in-depth understanding of the cork combustion dynamics and TPS response due to the SLS launch vehicle flight ascent environments.

thermal protection system↗
NASA NTRS1990

Wind-Tunnel Survey of an Oscillating Flow Field for Application to Model Helicopter Rotor Testing

A survey was conducted of the flow field produced by the Airstream Oscillator System (AOS) in the Langley Transonic Dynamics Tunnel (TDT). The magnitude of a simulated gust field was measured at 15 locations in the plane of a typical model helicopter rotor when tested in the TDT using the Aeroelastic Rotor Experimental System (ARES) model. These measurements were made over a range of tunnel dynamic pressures typical of those used for an ARES test. The data indicate that the gust field produced by the AOS is non-uniform across the tunnel test section, but should be sufficient to excite a model rotor.

Mirick, Paul H.↗
DOE OSTI2021

Flow behavior characterization of biomass Feedstocks

With the advancement of renewable energy, the processing and handling of biomass feedstocks has drawn enormous research interest. The key to economically viable and operationally reliable biomass handling processes involves a complete understanding of the flow behavior of different feedstocks as functions of the inherent critical material properties environmental conditions, and critical processing parameters. This review introduces the basic principles and methods in bulk solids flow and highlights recent efforts to understand the flow behavior of biomass feedstocks. The effects of inherent properties, environmental parameters, and handling equipment on the flow behavior of biomass feedstocks are presented. Particle size, shape, moisture, consolidation stress, temperature, storage time at rest, chemical treatment, and the material and geometry of the handling equipment all substantially influence biomass flowability. The limitations of current studies and the potential methods to overcome them are presented. Finally, an outlook for future research effort is provided, with proposed opportunities for improving the characterization of biomass flow.

Bulk solids testing↗
NASA NTRS1997

Angled Injection: Turbulent Flow Hybrid Bearings Comparison to Test Results

Hydrostatic/hydrodynamic (hybrid) journal bearings handling process liquids have limited dynamic stability characteristics and their application as support elements to high speed flexible rotating systems is severely restricted. Measurements on water hybrid bearings with angled orifice injection have demonstrated improved rotordynamic performance with virtual elimination of cross-coupled stiffness coefficients and null or negative whirl frequency ratios. A bulk-flow model for prediction of the static performance and force coefficients of hybrid bearings with angled orifice injection is advanced. The analysis reveals that the fluid momentum exchange at the orifice discharge produces a pressure rise in the hydrostatic recess retards the shear flow induced by journal rotation, and thus, reduces cross-coupling forces. The predictions from the model are compared with experimental measurements for a 45 deg. angled orifice injection, 5 recess water hybrid bearing operating at 10.2, 17.4, and 24.6 krpm and with supply pressures of 4, 5.5, and 7 MPa. The correlations include recess pressures, flow rates, and rotordynamic force coefficients at the journal centered position.

SanAndres, Luis↗
NASA NTRS1993

Experimental study of three exit pressure distortions on turbine performance

A cold flow air test of the Space Shuttle Main Engine (SSME) High Pressure Fuel Turbopump (HPFTP) turbine was conducted with a circumferential pressure distortion at the turbine exit. The effects of three circumferential exit pressure distortions on turbine efficiency and pressure ratio, are presented. Circumferential and radial total pressure, total temperature, static pressure, and flow angle distributions at the turbine exit are also presented. Efficiency and total-to-total pressure ratio are shown to have a circumferential variation as high as 13.7 percent (or points of efficiency) and 7.1 percent, respectively. A slight pressure distortion was measured downstream of the first stage nozzle and the distortion increased across subsequent blade rows to a maximum downstream of the second stage rotor for all three plates. A brief discussion of the test facility, model, instrumentation, and test plan is given for completeness.

Gaddis, Stephen W.↗
NASA NTRS1978

A new technique for reducing test section noise in supersonic wind tunnels

A new technique is presented for obtaining a low-noise test environment in a high-speed wind tunnel. This technique utilizes the fact that the primary noise source for high supersonic/hypersonic wind tunnels is radiated noise from the turbulent, tunnel-wall boundary layer. Because of the high directionality of sound in supersonic flows this test section noise originates far upstream on the walls of the nozzle at the 'acoustic origin'. It is shown that tailoring the nozzle contour to reduce the acoustic origin Mach number significantly reduces the noise level in the upstream half of the nozzle test rhombus. Experimental noise measurements are presented from a conventional, Mach 5 nozzle and are compared with measurements from a rapid-expansion, Mach 5 nozzle.

Anders, J. B.↗