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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 163 records · Page 9
All sourcesNASA NTRSDOE OSTI
NASA NTRS2017

Relating a Jet-Surface Interaction Experiment to a Commercial Supersonic Transport Aircraft Using Numerical Simulations

Reynolds-Averaged Navier-Stokes (RANS) simulations were performed for a commercial supersonic transport aircraft concept and experimental hardware models designed to represent the installed propulsion system of the conceptual aircraft in an upcoming test campaign. The purpose of the experiment is to determine the effects of jet-surface interactions from supersonic aircraft on airport community noise. RANS simulations of the commercial supersonic transport aircraft concept were performed to relate the representative experimental hardware to the actual aircraft. RANS screening simulations were performed on the proposed test hardware to verify that it would be free from potential rig noise and to predict the aerodynamic forces on the model hardware to assist with structural design. The simulations showed a large region of separated flow formed in a junction region of one of the experimental configurations. This was dissimilar with simulations of the aircraft and could invalidate the noise measurements. This configuration was modified and a subsequent RANS simulation showed that the size of the flow separation was greatly reduced. The aerodynamic forces found on the experimental models were found to be relatively small when compared to the expected loads from the model’s own weight.Reynolds-Averaged Navier-Stokes (RANS) simulations were completed for two configurations of a three-stream inverted velocity profile (IVP) nozzle and a baseline single-stream round nozzle (mixed-flow equivalent conditions). For the Sideline and Cutback flow conditions, while the IVP nozzles did not reduce the peak turbulent kinetic energy on the lower side of the jet plume, the IVP nozzles did significantly reduce the size of the region of peak turbulent kinetic energy when compared to the jet plume of the baseline nozzle cases. The IVP nozzle at Sideline conditions did suffer a region of separated flow from the inner stream nozzle splitter that did produce an intense, but small, region of turbulent kinetic energy in the vicinity of the nozzle exit. When viewed with the understanding that jet noise is directly related to turbulent kinetic energy, these IVP nozzle simulations show the potential to reduce noise to observers located below the nozzle. However, these RANS simulations also show that some modifications may be needed to prevent the small region of separated flow-induced turbulent kinetic energy from the inner stream nozzle splitter at Sideline conditions.

Reynolds-Averaged Navier Stokes↗
DOE OSTI2025

Nanofiltration Membranes for Li + /Mg 2+ Separation: Materials and Mechanisms

Nanofiltration (NF) membranes have garnered significant interest for Li + /Mg 2+ separation, a crucial step in lithium extraction from brines. The state-of-the-art commercial LiNE-XD membrane exhibits a Li + /Mg 2+ separation factor (SF Li/Mg ) of 42 at pH 3.3, due to the positive charges on the membrane surface and its strong size-sieving ability. Membranes with higher separation factors at a broad pH range are being pursued to improve separation efficiency. This work aims to provide a timely and comprehensive assessment of advanced NF membranes with superior Li + /Mg 2+ separation properties, as well as their structure and property relationships for designing next-generation membranes. We describe transport mechanisms for ions in NF membranes and discuss governing parameters and models employed to quantify the Li + /Mg 2+ separation. High-performance membrane materials are exhaustively introduced, including commercial and modified polyamides, two-dimensional materials, metal–organic frameworks, crown ethers, and their blends. Finally, we critically compare these membranes in an upper bound plot and highlight the opportunities and challenges of NF membranes for practical Li + /Mg 2+ separations.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Dianhydride-Modified Graphitic Carbon Nitride as a Support for Cobalt Single-Atom Photocatalysts

Graphitic carbon nitride (C 3 N 4 ) has been widely explored as a photoactive support for single-atom catalysts (SACs). In this paper, three different π-rich aromatic dianhydrides are employed to introduce molecular quantized trap states into the conduction band of C 3 N 4 to facilitate efficient charge-separation and to promote an enhanced photocatalytic CO 2 reduction response. These modified C 3 N 4 materials have been characterized structurally and spectroscopically for use as the support for Co-based SACs. In photocatalytic CO 2 reduction studies, the Co SAC on naphthalene dianhydride doped C 3 N 4 exhibited the highest activity and selectivity towards CO production among the Co SACs tested in this work. The observed improvement in photocatalytic CO 2 -to-CO conversion activity correlates with trends in photoinduced charge separation, as revealed by photoluminescence spectroscopy.

14 SOLAR ENERGY↗
DOE OSTI2024

Pressure-Gradient-Based RANS Model for Predicting Separation in Transitional and Turbulent Flows

Predicting flow separation poses a significant challenge for RANS models, particularly in transitional flows over airfoils. We propose a novel improvement to RANS models to predict incipient separation in both transitional and fully turbulent flows. Our approach modifies the eddy viscosity model in regions indicated by a pressure-gradient criterion that accounts for intermittency - determining whether the boundary layer is laminar or turbulent. This model demonstrates robust generalization across various airfoil shapes and Reynolds numbers. Applied to the NREL Phase VI wind turbine rotor, our model shows improved aerodynamic performance predictions compared to the baseline RANS model.

k-omega SST↗
NASA NTRS1984

A concept for reducing oceanic separation minima through the use of a TCAS-derived CDTI

A concept for using a cockpit display of traffic information (CDTI), as derived from a modified version of the Traffic Alert and Collision Avoidance System 2 (TCAS 2), to support reductions in air traffic separation minima for an oceanic track system is presented. The concept, and the TCAS modifications required to support it, are described. The feasibility of the concept is examined from a number of standpoints, including expected benefits, maximum alert rates, and possible transition strategies. Various implementation issues are analyzed. Pilot procedures are suggested for dealing with alert situations. Possible variations of the concept are also examined. Finally, recommendations are presented for other studies and simulation experiments which can be used to further verify the feasibility of the concept.

Love, W. D.↗
NASA NTRS2021

A New Method for Predicting Turbulent Flow Reattachment Location: Application of Stratford Criterion for Reattaching Flows

A new method for predicting turbulent flow reattachment location has been developed. The method predicts the reattachment location using the surface static pressure distribution and requires only a single empirical parameter. The method is based on the well-known Stratford’s flow separation criterion, which results from an approximate solution to the equations of motion within the boundary layer. Because of the large pressure rise, the original Stratford separation criterion is not valid for reattaching flows. In order to apply the Stratford criterion for reattaching flows, the reference location was moved to the pressure drop conditions instead of pressure rise conditions. In addition, the pressure distribution was scaled using a technique that was originally introduced for supersonic base flows. A new empirical parameter was also obtained for the modified Stratford criterion. The method has been tested for 30 different separated flow configurations from the literature. The variety of test cases include subsonic flows, transonic flows, 2D flows, and axisymmetric flows, with experimental as well as high resolution numerical simulation results. The flow reattachment predictions with the new method agree very well with the reported data. The error is less than 5% and typically about 2%. The new method is an extremely simple and a quick way of finding the reattachment location. Given the complexities of the existing experimental techniques for finding the reattachment location, the method easily and quickly provides the flow reattachment location, which could be used to estimate the physical extent of separation bubbles, as a performance index for flow control methods, or to assess the predictive capability of turbulence models.

Flow reattachment location↗
NASA NTRS2002

Effects of Endwall Geometry and Stacking on Two-Stage Supersonic Turbine Performance

The drive towards high-work turbines has led to designs which can be compact, transonic, supersonic, counter rotating, or use a dense drive gas. These aggressive designs can lead to strong secondary flows and airfoil flow separation. In many cases the secondary and separated flows can be minimized by contouring the hub/shroud endwalls and/or modifying the airfoil stacking. In this study, three-dimensional unsteady Navier-Stokes simulations were performed to study three different endwall shapes between the first-stage vanes and rotors, as well as two different stackings for the first-stage vanes. The predicted results indicate that changing the stacking of the first-stage vanes can significantly impact endwall separation (and turbine performance) in regions where the endwall profile changes.

Dorney, Daniel J.↗
NASA NTRS1946

Performance of the Modified V-1710-93 Engine-Stage Supercharger with a Constant-Area Vaneless Diffuser

As part of an investigation to increase the power output of the V-1710-93 engine at altitude, the engine-stage supercharger was combined with a constant-area vaneless diffuser designed to improve the performance of the engine-stage supercharger at the rated engine operating point. The performance of the modified supercharger was investigated in a variable-component supercharger test rig and compared with that of the standard supercharger with an 8-vaned diffuser. A separate evaluation of the component efficiencies and a study of the flow characteristics of the modified supercharger was made possible by internal diffuser instrumentation. At the volume flow required by the engine for rated operating conditions, the modified supercharger increased the over-all adiabatic efficiency 0.05 and the over-all pressure coefficient 0.035. Furthermore, the capacity of the engine-stage supercharger was increased by replacing the standard 8-vaned diffuser with the vaneless diffuser. The peak over-all adiabatic efficiency for the modified supercharger, however, was 0.05 to 0.07 lower than that of the standard unit over the range of tip speeds investigated. The improved performance of the modified supercharger at rated engine operating conditions resulted from a shift of the point of peak adiabatic efficiency and pressure coefficient of the standard supercharger to a higher flow. The energy loss through the vaneless diffuser was found to be small. Because of the restricted diffuser diameter, however, diffusion was inadequate, which resulted in a relatively small static-pressure rise through the diffuser, high diffuser-exit velocities, and excessive collector-case losses.

Douglas, John E.↗
DOE OSTI2025

Simulated Moving Bed Process for CO 2 Capture from Humid Postcombustion Flue Gases Using MUF-16

Simulated moving bed (SMB) designs are increasingly being adapted for the separation of multicomponent gaseous mixtures. In this work, we develop a modified SMB process for capturing CO 2 from humid postcombustion flue gas using MUF-16 (MUF = Massey University Framework). MUF-16 shows excellent selectivity for CO 2 over N 2 , moderate heats of adsorption for CO 2 and H 2 O, and no competitive sorption of CO 2 over water at relative humidities relevant to postcombustion capture. We utilize these characteristics to propose a continuous process that uses N 2 from the feed as the desorbent for the water, eliminating the need for a separate desiccant bed and allowing for localized heating during desorption for H 2 O-saturated MOF beds. Single-component isotherms, single-column breakthrough experiments, and SO 2 stability tests suggest the excellent suitability of MUF-16 to this separation via the proposed SMB design.

CO2 capture from humid flue gas↗
NASA NTRS1979

An investigation of corner separation within a thrust augmenter having Coanda jets

The development of separation in corners of thrust augmentor wings having Coanda jets was investigated using hot film surface sensors and pressure transducers. Separation on the test augmentor began at a corner very close to the augmentor exit and then rapidly proceeded upstream. Measurements of the pressure fields in the corner region indicated that a modified form of the Stratford criterion could be used to predict the onset of separation. Testing was conducted over a range of nozzle pressure ratios, aspect ratios, diffuser angles, and designs of the boundary layer and Coanda nozzles.

Seiler, M. R.↗
NASA NTRS1983

Computation of supersonic viscous flows around pointed bodies at large incidence

A recently reported parabolized Navier-Stokes method has been extended to compute turbulent supersonic flows around cones and an ogive-cylinder body at large incidence. The algebraic eddy-viscosity turbulence model contained in the code was modified to properly account for the large regions of cross-flow separation that occur in these flows. Extensive comparisons between computed results and experimentally measured flow fields are presented. The results show good agreement for viscous-layer profiles and details of the external leeward-side vortex structure at angles of attack up to three times the cone half angles. Details of the modified turbulence model are presented and discussed.

Degani, D.↗
DOE OSTI2024

Discerning the effect of various irradiation modes on the corrosion of Zircaloy-4

Using proton irradiation, this study investigates the individual influence of several factors on the corrosion kinetics of Zircaloy-4 in a hydrogenated water environment simulating a Pressurized Water Reactor (PWR). Using both simultaneous irradiation-corrosion and autoclave corrosion, we separately examine: (i) the effect of pre-irradiation on modifying the structure of the material, (ii) the impact of irradiation on creating defects in the growing oxide layer during corrosion, and (iii) the influence of irradiation on increasing the corrosion potential through radiolysis during corrosion. To replicate neutron-irradiated microstructure, two proton pre-irradiation schedules were employed: Schedule 1 (isothermal irradiation at 350 °C to 5 dpa) to simulate high-temperature PWR conditions, and Schedule 2 (two-step process: irradiation to 2.5 dpa at -10 °C followed by 2.5 dpa at 350 °C) to simulate lower temperature PWR and Boiling Water Reactor (BWR) conditions. Long-term autoclave corrosion testing over 360 days at 320 °C revealed no significant difference between unirradiated samples and those pre-irradiated according to either schedule, with all samples exhibiting sub-cubic kinetics within the pre-transition regime. Irradiated samples underwent Simultaneous Irradiation Corrosion (SIC) tests, corroding in 320 °C water while being irradiated with protons. Corrosion was found to accelerate in all SIC-tested samples relative to autoclave conditions, with the greatest increase observed in non-pre-irradiated samples. Pre-irradiation with either schedule resulted in a slower corrosion rate compared to non-pre-irradiated regions under SIC conditions. The degree of radiolysis observed in the SIC tests surpassed typical PWR conditions, approaching levels found in BWRs. Radiolysis products were identified as the primary contributors to accelerated corrosion, corroborated by radiolysis bar tests. Furthermore, these findings underscore the intricate interactions between irradiation, corrosion, and water chemistry in determining Zircaloy-4 corrosion kinetics within nuclear reactor environments.

Pressurized Water Reactor↗
DOE OSTI2025

Driving Selectivity Among Rare Earth Elements through Phase Modifiers

Phase modifiers are low molecular weight molecules added to solvent extraction separations to improve the physical performance of the separation system, for example by increasing the concentration of metal ions that can be separated or improving the compatibility of the two solvents.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1981

Some modifications to, and operational experiences with, the two-dimensional, finite-difference, boundary-layer code, STAN5

The two-dimensional, finite-difference boundary-layer code, STAN5, is the primary tool used at the NASA-Lewis Research Center for predicting turbine blade gas-side heat-transfer coefficients. A number of modifications have been made to the program to enhance its usefulness for these calculations. Experience in using STAN5 has identified some problems in the program that can be treated through program input, without modifying the program. These include the presence of a small separation bubble near the leading edge, and the effect of full-coverage film cooling on transition to turbulence. Some of the techniques used to treat these problems are described.

Gaugler, R. E.↗
NASA NTRS1991

Deployment and testing of a second prototype expandable surgical chamber in microgravity

During microgravity exposure, two separate expandable surgical chambers were tested. Both chambers had been modified to fit the microgravity work station without extending over the sides of the table. Both chambers were attached to a portable laminar flow generator which served two purposes: to keep the chambers expanded during use; and to provide an operative area environment free of contamination. During the tests, the chambers were placed on various parts of a total body moulage to simulate management of several types of trauma. The tests consisted of cleansing contusions, debridement of burns, and suturing of lacerations. Also, indigo carmine dye was deliberately injected into the chamber during the tests to determine the ease of cleansing the chamber walls after contamination by escaping fluids. Upon completion of the tests, the expandable surgical chambers were deflated, folded, and placed in a flattened state back into their original containers for storage and later disposal. Results are briefly discussed.

Markham, Sanford M.↗
NASA NTRS1993

Photogeological analysis of Europan tectonic features

Preliminary photogeological analyses of the Pelorus Linea and Sidon Flexus regions of Europa were conducted to explore the proposal by Schenk that lateral motion of crustal blocks has occurred in a 'rift zone' including possible strike-slip, tension fracturing, and geometric plate rotation about an Euler pole. These analyses revealed features interpreted as tensional structures and block rotation in a strike-slip regime consistent with the Schenk hypotheses and implied the presence of at least two stages of crustal deformation consistent with a chronology developed by Lucchitta. Confirmation of regional scale Euler pole rotation was ambiguous, however. Up to 80 kilometers of possible extension was identified in the rift zone; to accommodate this, 'cryosubduction' is speculatively proposed as a mechanism for recycling Europan 'ice lithosphere'. The cumulative width of wedge-shaped bands included in the rift zone was measured and plotted versus distance from the inferred rotation pole. Three sharp decreases in the total width were noted. These occur roughly where certain triple bands cross the rift zone suggesting that the bands are structural features that predate and influence the zone. While the curve hints at one or more sinusoidal relationships consistent with rotation geometry, given the low photographic resolution and the preliminary nature of this examination the question of whether the observations represent coherent regional rotation modified by crosscutting structures or instead imply independent local rotations separated by these structures is unanswered by this analysis.

Tufts, B. R.↗
NASA NTRS2002

Constellation X-Ray Mission and Support

This report is a supplement to the Third Annual Report summarizing work performed by the Smithsonian Astrophysical Observatory (SAO) for NASA Goddard Space Flight Center (GSFC) under Cooperative Agreement NCC5-3681. The Agreement is entitled 'Constellation X-ray Mission Study and Support.' This supplementary report covers the period from October 1, 2001 through January 10, 2002. The report has been prepared and submitted to ensure that the Constellation-X Project Office at GSFC has current performance information needed to evaluate a proposed modified budget for FY02. That proposed budget is being submitted separately. SAO continues to perform work under the overall direction of Dr. Harvey Tananbaum, the SAO Principal Investigator for the program. Mr. Robert Rasche is the SAO Program Manager and is responsible for day-to-day program management at SAO and coordination with GSFC. The report summarizes the main areas of SAO activity. Most of the work has been done jointly with personnel from GSFC and Marshall Space Flight Center (MSFC). We describe SAO participation in these efforts. Under the Agreement, SAO performed work in seven major areas of activity. These areas related to: (1) Constellation X-ray Mission Facility Definition Team and Study Management; (2) Science Support; (3) Spectroscopy X-ray Telescope (SXT); (4) Systems Engineering; (5) Travel in Support of the Work Effort; and (6) In-house Management and Coordination.

Tananbaum, H.↗
NASA NTRS2001

Modeling Feedbacks Between Water and Vegetation in the Climate System

Not only is water essential for life on earth, but life itself affects the global hydrologic cycle and consequently the climate of the planet. Whether the global feedbacks between life and the hydrologic cycle tend to stabilize the climate system about some equilibrium level is difficult to assess. We use a global climate model to examine how the presence of vegetation can affect the hydrologic cycle in a particular region. A control for the present climate is compared with a model experiment in which the Sahara Desert is replaced by vegetation in the form of trees and shrubs common to the Sahel region. A second model experiment is designed to identify the separate roles of two different effects of vegetation, namely the modified albedo and the presence of roots that can extract moisture from deeper soil layers. The results show that the presence of vegetation leads to increases in precipitation and soil moisture in western Sahara. In eastern Sahara, the changes are less clear. The increase in soil moisture is greater when the desert albedo is replaced by the vegetation albedo than when both the vegetation albedo and roots are added. The effect of roots is to withdraw water from deeper layers during the dry season. One implication of this study is that the insertion of vegetation into the Sahara modifies the hydrologic cycle so that the vegetation is more likely to persist than initially.

Miller, James R.↗