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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 307 records · Page 17
All sourcesNASA NTRSDOE OSTI
NASA NTRS2021

Transition Analysis for Isolated Trips on BOLT-II Wind-Tunnel and Flight Configuration

The BOLT-II configuration designed for an upcoming flight experiment exemplifies the complexities of hypersonic boundary layer transition in the presence of multiple and potentially interacting instability mechanisms. The present paper is related to the NASA-led roughness experiment on the secondary side of the BOLT-II configuration. First, computations are performed to aid mean-flow based correlations for the transition measurements acquired during an experimental campaign in the Ludwieg Tube facility at the United States Air Force Academy. To that end, both laminar and turbulent flow computations are performed for selected conditions of the experiment with a 1:3 scale model of the slightly shorter BOLT configuration. The variation in well-known correlation parameters for transition due to isolated roughness elements with respect to element position, height, and flow Reynolds number is delineated. Furthermore, the wake instability theory is used to examine the amplification of unstable disturbances behind the centerline trip at the design conditions of the BOLT-II flight experiment and for its dynamically scaled version on the 1:3 scale model of the wind tunnel experiment. To our knowledge, this study represents the first analysis of the wake instabilities in the presence of a prominent entropy layer outside the boundary layer. At the nominal flight design condition of Re ∞ ) = 5.44 and Re ∞ = 2.5 x 10 6 /m, a diamond planform (“pizza-box”) trip with k/δ = 0.70 and planform-halfwidth-to-height ratio of b/k = 3.0 at X/L = 0.254 induces a strong distortion of the boundary-layer flow in the vicinity of the symmetry plane, such that the wake structure includes a centerline streak produced by the flow retardation behind the trip along with multiple additional, prominent vorticity structures representing the necklace vortex system. Stability results reveal that each of these streaks can support a strong amplification of wake instabilities within a frequency band of 95 kHz–255 kHz, with a peak N-factor of greater than 15 beyond X/L ≈ 0.42. The dynamically scaled wind tunnel configuration with Re ∞ = 20.25 x 10 6 /m is also found to support N > 15 at similar axial stations.

BOLT↗
NASA NTRS2021

Transition Analysis for Isolated Trips on BOLT-II Wind-Tunnel and Flight Configuration

The BOLT-II configuration designed for an upcoming flight experiment exemplifies the complexities of hypersonic boundary layer transition in the presence of multiple and potentially interacting instability mechanisms. The present paper is related to the NASA-led roughness experiment on the secondary side of the BOLT-II configuration. First, computations are performed to aid mean-flow based correlations for the transition measurements acquired during an experimental campaign in the Ludwieg Tube facility at the United States Air Force Academy. To that end, both laminar and turbulent flow computations are performed for selected conditions of the experiment with a 1:3 scale model of the slightly shorter BOLT configuration. The variation in well-known correlation parameters for transition due to isolated roughness elements with respect to element position, height, and flow Reynolds number is delineated. Furthermore, the wake instability theory is used to examine the amplification of unstable disturbances behind the centerline trip at the design conditions of the BOLT-II flight experiment and for its dynamically scaled version on the 1:3 scale model of the wind tunnel experiment. To our knowledge, this study represents the first analysis of the wake instabilities in the presence of a prominent entropy layer outside the boundary layer. At the nominal flight design condition of Re ∞ ) = 5.44 and Re ∞ = 2.5 x 10 6 /m, a diamond planform (“pizza-box”) trip with k/δ = 0.70 and planform-halfwidth-to-height ratio of b/k = 3.0 at X/L = 0.254 induces a strong distortion of the boundary-layer flow in the vicinity of the symmetry plane, such that the wake structure includes a centerline streak produced by the flow retardation behind the trip along with multiple additional, prominent vorticity structures representing the necklace vortex system. Stability results reveal that each of these streaks can support a strong amplification of wake instabilities within a frequency band of 95 kHz–255 kHz, with a peak N-factor of greater than 15 beyond X/L ≈ 0.42. The dynamically scaled wind tunnel configuration with Re ∞ = 20.25 x 10 6 /m is also found to support N > 15 at similar axial stations.

BOLT↗
NASA NTRS2021

Wake Instability Behind Isolated Trip Near the Leading Edge of the BOLT-II Configuration

The BOLT-II (Holden Mission) configuration is an extended version of the BOLT flight article and depicts hypersonic boundary-layer transition in the presence of multiple and potentially interacting instability mechanisms. Several numerical studies of the boundary-layer instabilities over these configurations have been reported in the recent literature, including our previous studies of the modal instability characteristics of boundary-layer streaks adjacent to the minor-axis symmetry plane of the BOLT configuration and the wake instabilities behind a diamond planform (“pizza-box”) trip along the symmetry plane on the secondary side of the BOLT-II configuration. The present work extends the latter study to a scaled version of the same trip that is located in the region of nonzero crossflow in the vicinity of the leading edge at X/L = 0.5. Collectively, the trips along the symmetry plane and near the leading edge are the focus of the NASA roughness experiment on the secondary side of the BOLT-II configuration. The laminar basic state computation at the nominal flight design condition of Re ∞ = 5.44 x 10 6 /m and Re ∞ = 2.5 x 10 6 /m shows that the leading-edge trip with k/δ ≈ 0.70 and planform-side-length-to-height ratio of b/k = 3.0 induces multiple asymmetric, longitudinal streaks within the trip wake. The most prominent streak among these resembles a finite amplitude crossflow vortex, and it supports the amplification of multiple families of unstable modes. The application of multi-dimensional instability analysis to the wake flow reveals that the most amplified unstable mode can achieve a peak N-factor of up to 20 by X/L = 0.80, indicating that the onset of transition is more than likely to occur within eighty percent of the model length. To the best of our knowledge, the present study represents the first analysis including nonparallel and curvature effects on hypersonic tripwake instabilities in the presence of boundary-layer crossflow over a three-dimensional configuration.

Boundary layer transition↗
NASA NTRS2024

EVA Operations for the Artemis III Science Team

The purpose of this presentation is to give the newly selected Artemis III Science Team some basic information on EVA Operations and potential interactions with the science team in both the planning and real-time phases of the mission.

EVA↗
NASA NTRS2024

Simulating the Volcanic Sulfate Aerosols From the 1991 Eruption of Cerro Hudson and Their Impact on the 1991 Ozone Hole

The Chilean volcano Cerro Hudson erupted between August 8th and 15th, 1991, injecting between 1.7 and 2.9 Tg of SO2 into the upper troposphere and lower stratosphere. We simulate this injection using the GEOS Earth system model with detailed sulfur chemistry and sectional aerosol microphysics, focusing on the resulting aerosols and their contribution to the 1991 Antarctic Austral Springtime ozone hole. The simulations show a column ozone deficit (12 DU) in the Southern Hemisphere vortex collar region. The majority of this effect is between 10 and 20 km and due to heterogeneous chemistry. The model shows a 26% decrease in ozone from background levels at these altitudes, compared with in-situ observations of a 50% decrease. Above 20 km, the dynamical response to the eruption also causes lower ozone values, a novel modeling result. This experiment highlights potential interactions between proposed solar radiation management geoengineering aerosols and volcanic eruptions.

aerosols↗
DOE OSTI2024

The Meaning of Risk for Safety, Security, and Safeguards in the Design of Advanced Nuclear Reactors

What is the meaning of risk as it applies to the design of advanced reactors in the disciplines of safety, security, and safeguards? How can we find common terminology for the concept of risk and how can we find interfaces between these disciplines? These are important questions that should be explored in order that they may be applied in an integrated manner for the most effective and efficient design approaches. Eliminating or minimizing risks is a key design driver that motivates and informs the development of nuclear reactors. For safety, risk is well understood and applied in Probabilistic Risk Assessments. For security, the risk-based concepts of vulnerability assessments and vital areas are all considered in designing security systems. For safeguards, the concept of risk is not formally defined, as it relates to the design and operation of nuclear reactors. International nuclear safeguards seek to reduce the risk of proliferation in the nuclear fuel cycle and as such the concept of risk does exist. Therefore, the current understanding of the “3S’ approach, which seeks to find the interfaces and conflicts between safety, security, and safeguards requires a thorough understanding of the role that the reduction of risk plays in all three disciplines. The intersection of risk for safety and security is now being developed as there is a strong correlation between reactor design and operations and their vulnerability to sabotage. The intersection of risk for security and safeguards has to date chiefly been focused on the nuclear material control and accounting systems, which are relied on by both the operator (State) and the IAEA. This paper explores the concept of risk in each of the three disciplines, how they interact, potential conflicts and interfaces , how these might be addressed and leveraged, and a notional framework for how this could be achieved.

Kovacic, Donald N↗
NASA NTRS1983

Finite-difference simulation of transonic separated flow using a full potential boundary layer interaction approach

A new, fast, direct-inverse, finite-difference boundary-layer code has been developed and coupled with a full-potential transonic airfoil analysis code via new inviscid-viscous interaction algorithms. The resulting code has been used to calculate transonic separated flows. The results are in good agreement with Navier-Stokes calculations and experimental data. Solutions are obtained in considerably less computer time than Navier-Stokes solutions of equal resolution. Because efficient inviscid and viscous algorithms are used, it is expected this code will also compare favorably with other codes of its type as they become available.

Van Dalsem, W. R.↗
NASA NTRS1989

Detection of potential space station control/structure interaction with CO-ST-IN

The NASA Lewis Research Center is concerned with the potential of interaction between space station controllers and the solar PV array structures. The models required to handle this problem are very large, and automated methods were developed for the transfer of data between structural dynamic and control system analysis software. These methods emphasize the need to achieve accurate coupled analysis results while using as small a model as possible. Specific tools which help the analyst in this regard include modal order techniques, the use of mode acceleration to calculate internal loads and stresses and the transfer of Craig-Bampton components to reduce problems associated with modal sufficiency. These techniques were applied to a space station model with 366 modes below 1 Hz. Attitude control, and alpha and beta joint control were simulated. The inclusion of alpha and beta joint controllers is important when examining overall space station dynamics. An initial choice of control parameters does indicate a potential for control/structure interaction during reboost. As expected this is exacerbated by increasing the rate gain and decreasing the hysteresis of the reaction control system (RCS) in order to improve rigid body performance.

Carney, Kelly↗
DOE OSTI2024

Initial Laboratory Measurements Probing Hydrogen Interactions with Eagle Ford Shale and Pyrite: Potential Implications for Subsurface Hydrogen Storage

Hydrogen (H 2 ) has the potential to be a transformative technology as an enabler to a low-carbon future and promoter of renewable energy. When H 2 is injected and stored in the subsurface, it has the potential to interact with the caprock (usually shale) which overlies and seals the storage reservoir. Here, this study examines geochemical reactions or changes in surface morphology to Eagle Ford Shale, a proxy for caprock, upon exposure to H 2 at 50°C and 10.3 MPa. Reactions were also performed with N 2 to provide an experimental control. Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM-EDS), Atomic Force Microscopy (AFM), and Optical Photothermal-Infrared (O-PTIR) Spectroscopy were applied to quantify changes on the microscale and nanoscale level. Fluid chemistry changes were monitored with Ion Chromatography (IC) and Inductively Coupled Plasma Mass Spectrometry (ICP-MS). Exposure of Eagle Ford Shale to H 2 gas alone did not result in any alterations to the shale chemically or any changes in the surface morphology. Exposure of Eagle Ford Shale to both H 2 and water as well as N 2 and water resulted in changes to the surface morphology because of gypsum dissolution and reprecipitation, thus indicating that H 2 is not necessary to promote changes. Pure pyrite was the most reactive with H 2 possibly resulting in a reduction to pyrrhotite. These initial studies suggest that the extent of reactions activated by hydrogen with caprock are minor under the temperature and pressure conditions that would represent underground hydrogen storage.

08 HYDROGEN↗
DOE OSTI2024

Multilevel analysis between Physcomitrium patens and Mortierellaceae endophytes explores potential long‐standing interaction among land plants and fungi

SUMMARY The model moss species Physcomitrium patens has long been used for studying divergence of land plants spanning from bryophytes to angiosperms. In addition to its phylogenetic relationships, the limited number of differential tissues, and comparable morphology to the earliest embryophytes provide a system to represent basic plant architecture. Based on plant–fungal interactions today, it is hypothesized these kingdoms have a long‐standing relationship, predating plant terrestrialization. Mortierellaceae have origins diverging from other land fungi paralleling bryophyte divergence, are related to arbuscular mycorrhizal fungi but are free‐living, observed to interact with plants, and can be found in moss microbiomes globally. Due to their parallel origins, we assess here how two Mortierellaceae species, Linnemannia elongata and Benniella erionia , interact with P. patens in coculture. We also assess how Mollicute ‐related or Burkholderia ‐related endobacterial symbionts (MRE or BRE) of these fungi impact plant response. Coculture interactions are investigated through high‐throughput phenomics, microscopy, RNA‐sequencing, differential expression profiling, gene ontology enrichment, and comparisons among 99 other P. patens transcriptomic studies. Here we present new high‐throughput approaches for measuring P. patens growth, identify novel expression of over 800 genes that are not expressed on traditional agar media, identify subtle interactions between P. patens and Mortierellaceae, and observe changes to plant–fungal interactions dependent on whether MRE or BRE are present. Our study provides insights into how plants and fungal partners may have interacted based on their communications observed today as well as identifying L. elongata and B. erionia as modern fungal endophytes with P. patens .

59 BASIC BIOLOGICAL SCIENCES↗
NASA NTRS1999

Viscous Analysis of Ref. H Based Wing/Bodies

Computations have been performed on the baseline Reference H wing/body configuration, as well as the Wing 704 configuration, an optimized wing and fuselage combination derived from Ref. H through automated optimization. The parabolized Navier-Stokes solver UPS was employed with viscous terms in two directions in an effort to understand the source and level of potential viscous/inviscid interactions. The paper briefly describes the UPS code and the grids used to obtain the solutions before the discussion of results. Results of these computations indicate that viscous/inviscid interaction can contribute increments to both the pressure- and friction-related drag. Computations were performed for wind tunnel conditions-1.675% scale models at a Reynolds number of 4 million per foot. Turbulent flow results were obtained using the Baldwin-Lomax algebraic turbulence model and were compared with laminar flow results. The laminar flow fields were used to obtain upper bounds on potential interaction effects.

Lawrence, Scott L.↗
NASA NTRS1978

The effect of tip vortex structure on helicopter noise due to blade/vortex interaction

A potential cause of helicopter impulsive noise, commonly called blade slap, is the unsteady lift fluctuation on a rotor blade due to interaction with the vortex trailed from another blade. The relationship between vortex structure and the intensity of the acoustic signal is investigated. The analysis is based on a theoretical model for blade/vortex interaction. Unsteady lift on the blades due to blade/vortex interaction is calculated using linear unsteady aerodynamic theory, and expressions are derived for the directivity, frequency spectrum, and transient signal of the radiated noise. An inviscid rollup model is used to calculate the velocity profile in the trailing vortex from the spanwise distribution of blade tip loading. A few cases of tip loading are investigated, and numerical results are presented for the unsteady lift and acoustic signal due to blade/vortex interaction. The intensity of the acoustic signal is shown to be quite sensitive to changes in tip vortex structure.

Wolf, T. L.↗
NASA NTRS1980

Effect of tip vortex structure on helicopter noise due to blade-vortex interaction

A potential cause of helicopter impulsive noise, commonly called blade slap, is the unsteady lift fluctuation on a rotor blade due to interaction with the vortex trailed from another blade. The relationship between vortex structure and the intensity of the acoustic signal is investigated. Unsteady lift on the blades due to blade-vortex interaction is calculated using linear unsteady aerodynamic theory, and expressions are derived for the directivity, frequency spectrum, and transient signal of the radiated noise. The inviscid rollup model of Betz is used to calculate the velocity profile in the trailing vortex from the spanwise distribution of blade tip loading. A few cases of tip loading are investigated, and numerical results are presented for the unsteady lift and acoustic signal due to blade-vortex interaction. The intensity of the acoustic signal is shown to be quite sensitive to changes in tip vortex structures.

Widnall, S. E.↗
NASA NTRS2003

Multiple Changes to Reusable Solid Rocket Motors, Identifying Hidden Risks

The Space Shuttle Reusable Solid Rocket Motor (RSRM) baseline is subject to various changes. Changes are necessary due to safety and quality improvements, environmental considerations, vendor changes, obsolescence issues, etc. The RSRM program has a goal to test changes on full-scale static test motors prior to flight due to the unique RSRM operating environment. Each static test motor incorporates several significant changes and numerous minor changes. Flight motors often implement multiple changes simultaneously. While each change is individually verified and assessed, the potential for changes to interact constitutes additional hidden risk. Mitigating this risk depends upon identification of potential interactions. Therefore, the ATK Thiokol Propulsion System Safety organization initiated the use of a risk interaction matrix to identify potential interactions that compound risk. Identifying risk interactions supports flight and test motor decisions. Uncovering hidden risks of a full-scale static test motor gives a broader perspective of the changes being tested. This broader perspective compels the program to focus on solutions for implementing RSRM changes with minimal/mitigated risk. This paper discusses use of a change risk interaction matrix to identify test challenges and uncover hidden risks to the RSRM program.

Greenhalgh, Phillip O.↗
NASA NTRS1981

Effects of vane/blade ratio and spacing on fan noise

The effects of vane/blade ratio and spacing on fan noise are investigated to develop a fan noise prediction scheme which is calibrated against experimental data. A 44 blade, 0.504 diameter fan is used to demonstrate the production of fan noise data free from excess noise caused by rotor turbulence interaction. Two stator sets consisting of a cut-off set with 86 vanes, and a cut-on set of 48 vanes are used, with a total range of spacing from 0.5 to 2.3 rotor chords. The model includes viscous wake interaction noise and the potential field interactions of both the rotor and stator. A free-field acoustic environment is achieved by covering the walls, ceiling and floor with 0.7 m polyurethane foam wedges, providing less than + or - 1 dB standing wave ratio at 200 Hz. Only a 3 dB drop in tone level occurs as the spacing is increased from 0.5 to 2.3 rotor chords, and results indicate that the rotor wakes impinging on the stator vanes are the principal noise source for subsonic rotor speeds.

Kantola, R. A.↗