SEARCH · Engineering Papers

Results for “Environmental protection”

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.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,369 records · Page 76

All sources NASA NTRS DOE OSTI

NASA NTRS1972

Determination of aerothermodynamic environment uncertainties with application to space shuttle vehicles

In an effort to minimize the cost of the thermal protection system (TPS) for space shuttles, an analysis is made of environmental uncertainties. The basic categories of these uncertainties include aerodynamic heating, trajectory dispersions, atmospheric variations, and vehicle attitude variations. Also discussed are TPS design sensitivity to environmental uncertainties, and uncertainty profiles. Preliminary results indicate moderate TPS cost for a high confidence level environment may be obtained.

Scottoline, C. A.↗

NASA NTRS1994

Safety concerns for first entry operations of orbiting spacecraft

The Space Station Freedom crew will face operational problems unique to the spacecraft environment due to the absence of convection currents and the confined atmosphere within the habitable modules. Airborne contaminants from the materials offgassing or contingency incidents like thermodegradation may accumulate until they reach hazardous concentrations. Flow modeling and experiences from previous space flight missions confirm that caution must be exercised during first-entry operations. A review of the first-entry procedures performed during the Skylab Program will be presented to highlight the necessity for carefully planned operations. Many of the environmental conditions that can be expected on the Space Station are analogous to those which exist in confined storage or work spaces in the industrial setting. Experience with closed-loop environmental operations (e.g., atmospheric control of submarines) have also demonstrated that the buildup of trace contaminant gases could result in conditions that lead to mission termination or loss of crew. Consequently, some first-entry issues for the Station can be addressed by comparing them to familiar techniques developed on Earth. The instruments of the Environmental Health System (EHS) will provide the necessary monitoring capability to protect crew health and safety during the planned first-entry procedures of the MTC phase of the SSF Program. The authors of this paper will describe those procedures and will cite an example of the consequences when proper first-entry procedures are not followed.

Wilson, Steven H.↗

NASA NTRS2004

Thermal and Environmental Barrier Coatings for Advanced Propulsion Engine Systems

Ceramic thermal and environmental barrier coatings (TEBCs) are used in gas turbine engines to protect engine hot-section components in the harsh combustion environments, and extend component lifetimes. For future high performance engines, the development of advanced ceramic barrier coating systems will allow these coatings to be used to simultaneously increase engine operating temperature and reduce cooling requirements, thereby leading to significant improvements in engine power density and efficiency. In order to meet future engine performance and reliability requirements, the coating systems must be designed with increased high temperature stability, lower thermal conductivity, and improved thermal stress and erosion resistance. In this paper, ceramic coating design and testing considerations will be described for high temperature and high-heat-flux engine applications in hot corrosion and oxidation, erosion, and combustion water vapor environments. Further coating performance and life improvements will be expected by utilizing advanced coating architecture design, composition optimization, and improved processing techniques, in conjunction with modeling and design tools.

Zhu, Dong-Ming↗

NASA NTRS2001

Thermodynamics of Volatile Silicon Hydroxides Studied

Silicon-based ceramics are promising candidate structural materials for heat engines. The long-term stability of these materials to environmental degradation is dependent on the formation and retention of a protective SiO2 layer. It is well known that SiO2 forms stable volatile hydroxides in the presence of water vapor at elevated temperatures. Combustion conditions, which characteristically are at high velocities, contain significant water vapor pressures, and high temperatures tend to promote continuous formation of these hydroxides with resulting material degradation. For the degradation of silicon-based ceramics to be predicted, accurate thermodynamic data on the formation of silicon hydroxides are needed.

Copland, Evan H.↗

NASA NTRS2008

Thermal and Environmental Barrier Coating Development for Advanced Propulsion Engine Systems

Ceramic thermal and environmental barrier coatings (TEBCs) are used in gas turbine engines to protect engine hot-section components in the harsh combustion environments, and extend component lifetimes. Advanced TEBCs that have significantly lower thermal conductivity, better thermal stability and higher toughness than current coatings will be beneficial for future low emission and high performance propulsion engine systems. In this paper, ceramic coating design and testing considerations will be described for turbine engine high temperature and high-heat-flux applications. Thermal barrier coatings for metallic turbine airfoils and thermal/environmental barrier coatings for SiC/SiC ceramic matrix composite (CMC) components for future supersonic aircraft propulsion engines will be emphasized. Further coating capability and durability improvements for the engine hot-section component applications can be expected by utilizing advanced modeling and design tools.

Zhu, Dongming↗

NASA NTRS2014

Myanmar Ecological Forecasting: Utilizing NASA Earth Observations to Monitor, Map, and Analyze Mangrove Forests in Myanmar for Enhanced Conservation

Mangroves supply many essential environmental amenities, such as preventing soil erosion, filtering water pollution, and protecting shorelines from harmful waves, floods, storms and winds. The Mangroves in Myanmar not only provide citizens with a food source, but they also offer firewood, charcoal, and construction materials. The depletion of mangroves is threatening more than the biodiversity however; Myanmar's fiscal livelihood is also in harm's way. Mangroves are valued at $100,000 to $277,000 per square kilometer and if managed in a sustainable fashion, can infuse constant income to the emerging Myanmarese economy. This study analyzed three coastline regions, the Ayeyarwady Delta, Rakhine and Tanintharyi, and mapped the spatial extent of mangrove forest during the dry season in 2000 and 2013. The classifications were derived from Landsat 7 Enhanced Thematic Mapper Plus (ETM+) and Landsat 8 Operation Land Imager (OLI) imagery, as well as the Terra Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) digital elevation model information. This data was atmospherically corrected, mosaicked, masked and classified in ENVI, followed by ArcGIS to perform raster calculations and create final products. Forest degradation collected from 2000 to 2013 was later used to forecast the density and health of Mangroves in the year 2030. These results were subsequently presented to project partners Dr. Peter Leimgruber and Ellen Aiken at the Smithsonian Conservation Biology Institute in Front Royal, VA. After the presentation of the project to the partners, these organizations formally passed on to the Myanmar Ministry of Environment, Conservation and Forestry for policy makers and forest managers to utilize in order to protect the Myanmar mangrove ecosystem while sustaining a healthy economy.

Weber, Samuel J.↗

NASA NTRS2015

Integration of Product, Package, Process, and Environment: A Food System Optimization

The food systems slated for future NASA missions must meet crew nutritional needs, be acceptable for consumption, and use resources efficiently. Although the current food system of prepackaged, moderately stabilized food items works well for International Space Station (ISS) missions, many of the current space menu items do not maintain acceptability and/or nutritive value beyond 2 years. Longer space missions require that the food system can sustain the crew for 3 to 5 years without replenishment. The task "Integration of Product, Package, Process, and Environment: A Food System Optimization" has the objective of optimizing food-product shelf life for the space-food system through product recipe adjustments, new packaging and processing technologies, and modified storage conditions. Two emergent food processing technologies were examined to identify a pathway to stable, wet-pack foods without the detrimental color and texture effects. Both microwave-assisted thermal sterilization (MATS) and pressure-assisted thermal stabilization (PATS) were evaluated against traditional retort processing to determine if lower heat inputs during processing would produce a product with higher micronutrient quality and longer shelf life. While MATS products did have brighter color and better texture initially, the advantages were not sustained. The non-metallized packaging film used in the process likely provided inadequate oxygen barrier. No difference in vitamin stability was evident between MATS and retort processed foods. Similarly, fruit products produced using PATS showed improved color and texture through 3 years of storage compared to retort fruit, but the vitamin stability was not improved. The final processing study involved freeze drying. Five processing factors were tested in factorial design to assess potential impact of each to the quality of freeze-dried food, including the integrity of the microstructure. The initial freezing rate and primary freeze drying temperature and pressure were linked to final product quality in freeze-dried corn, indicating processing modifications that could lead to improved product shelf life. Storage temperatures and packaging systems were also assessed for the impact to food quality. Reduced temperature storage had inconclusive impact to the progression of rancidity in butter cookies. Frozen storage was detrimental to fruit and vegetable textural attributes but refrigerated storage helped to sustain color and organoleptic ratings for plant-based foods. With regard to packaging systems, the metallized film overwrap significantly decreased the progression of the rancidity of butter cookies as compared to the highest barrier non-metallized film. The inclusion of oxygen scavengers resulted in noticeable moisture gains in butter cookies over time, independent of packaging film systems. Neither emergent processing technology nor the freeze dry optimization resulted in compelling quality differences from current space food provisions such that a five-year shelf life is likely with these processing changes alone. Using a combination of refrigeration and PATS processing is expected to result in organoleptically-acceptable fruit quality for most fruits through five years. The vitamin degradation will be aided somewhat by the cold temperatures but, given the labile nature of vitamin C, a more stable fortification method, such as encapsulation, should also be investigated to ensure vitamin delivery throughout the product life. Similarly, significant improvement to the packaging film used in the MATS processing, optimization of formulation for dielectric properties, vitamin fortification, and reduced temperature storage should be investigated as a hurdle approach to reach a five year shelf life in wet-pack entrees and soups. Baked goods and other environmentally-sensitive spaceflight foods will require an almost impenetrable barrier to protect the foods from oxygen and moisture ingress but scavengers and reduced storage temperature did not improve baked good shelf life and are not recommended at this time for these foods.

Cooper, Maya R.↗

NASA NTRS2018

Coupled Thermo-Mechanical Micromechanics Modeling of the Influence of Thermally Grown Oxide Layer in an Environmental Barrier Coating System

Environmental Barrier Coatings (EBCs) have emerged as a promising means of protecting silicon based ceramic matrix composite (CMC) components for high temperature applications (e.g., aircraft engines). EBCs are often used to protect an underlying material (substrate) such as silicon carbide from extreme thermal/chemical environments. In a typical CMC/EBC system, an EBC may or may not be adhered to an underlying substrate with a bond coat (e.g., silicon). Irrespective, systems that utilize EBCs are susceptible to a number of failure modes including oxidation/delamination, recession, chemical attack and dissolution, thermomechanical degradation, erosion, and foreign object damage. Current work at NASA Glenn Research Center is aimed at addressing these failure modes in EBC systems and developing robust analysis tools to aid in the design process. The Higher-Order Theory for Functionally Graded Materials (HOTFGM), a precursor to the High-Fidelity Generalized Method of Cells micromechanics approach, was developed to investigate the coupled thermo-mechanical behavior of functionally graded composites and will be used herein to assess the development and growth of a low-stiffness thermally grown oxide (TGO) layer in EBC/CMC systems without a silicon bond coat. To accomplish this a sensitivity study is conducted to examine the influence of uniformly and nonuniformly grown oxide layer on the associated driving forces leading to mechanical failure (spallation) of EBC layer when subjected to isothermal loading.

thermally grown oxide↗

NASA NTRS2019

Pre-demonstration Development of Controlled-Release Corrosion Inhibitors and Healing Agents as Alternatives to Hexavalent Chromium

This Limited Scope Study was directed to achieve the following objectives:(1) Scale-up of materials that can meet MIL-PRF-23377 (solvent-based primer).(2) Provide evidence of resistance to aircraft alkaline cleaners and deicing fluids.(3) Provide formulation for initial ecological and toxicity screening.(4) Submit an interim report that will provide the basis for a future ESTCP demonstration effort.The encapsulation procedure for two corrosion inhibitors was scaled up from lab scale to 2.0 kg. This scale will accommodate high volume production of coatings with encapsulated corrosion inhibitors for large surface areas during a follow on ESTCP demonstration effort.Test results provided evidence of resistance to alkaline cleaners and aircraft deicing fluids and compliance with MIL-PRF-23377. All the MIL-PRF-23377 requirements were met with the exception of the adhesion requirement, in top coated panels, and the flexibility requirement. Work on solving these two problems will be done prior to validation and demonstration of the technology. An initial ecological and toxicity screening identified several factors that were not critical to the acceptance of the encapsulated corrosion inhibitor. This new technology will lead to environmentally friendly alternatives to hexavalent chromium that will enable DoD to protect its assets. Field demonstration, licensing, qualification, and commercialization will allow its real world utilization.

Calle, L. M.↗

NASA NTRS2018

Pre-Demonstration Development of Controlled-Release Corrosion Inhibitors and Healing Agents as Alternatives to Hexavalent Chromium

This Limited Scope Study was directed to achieve the following objectives: (1) Scale-up of materials that can meet MIL-PRF-23377 (solvent-based primer). (2) Provide evidence of resistance to aircraft alkaline cleaners and deicing fluids. (3) Provide formulation for initial ecological and toxicity screening. (4) Submit an interim report that will provide the basis for a future ESTCP demonstration effort. The encapsulation procedure for two corrosion inhibitors was scaled up from lab scale to 2.0 kg. This scale will accommodate high volume production of coatings with encapsulated corrosion inhibitors for large surface areas during a follow on ESTCP demonstration effort. Test results provided evidence of resistance to alkaline cleaners and aircraft deicing fluids and compliance with MIL-PRF-23377. All the MIL-PRF-23377 requirements were met with the exception of the adhesion requirement, in top coated panels, and the flexibility requirement. Work on solving these two problems will be done prior to validation and demonstration of the technology. An initial ecological and toxicity screening identified several factors that were not critical to the acceptance of the encapsulated corrosion inhibitor. This new technology will lead to environmentally friendly alternatives to hexavalent chromium that will enable DoD to protect its assets. Field demonstration, licensing, qualification, and commercialization will allow its real world utilization.

Alternatives to Hexavalent Chromium↗

NASA NTRSDate not supplied

Pre-Demonstration Development of Controlled-Release Corrosion Inhibitors and Healing Agents as Alternatives to Hexavalent Chromium

This Limited Scope Study was directed to achieve the following objectives: (1) Scale-up of materials that can meet MIL-PRF-23377 (solvent-based primer). (2) Provide evidence of resistance to aircraft alkaline cleaners and deicing fluids. (3) Provide formulation for initial ecological and toxicity screening. (4) Submit an interim report that will provide the basis for a future ESTCP demonstration effort. The encapsulation procedure for two corrosion inhibitors was scaled up from lab scale to 2.0 kg. This scale will accommodate high volume production of coatings with encapsulated corrosion inhibitors for large surface areas during a follow on ESTCP demonstration effort. Test results provided evidence of resistance to alkaline cleaners and aircraft deicing fluids and compliance with MIL-PRF-23377. All the MIL-PRF-23377 requirements were met with the exception of the adhesion requirement, in top coated panels, and the flexibility requirement. Work on solving these two problems will be done prior to validation and demonstration of the technology. An initial ecological and toxicity screening identified several factors that were not critical to the acceptance of the encapsulated corrosion inhibitor. This new technology will lead to environmentally friendly alternatives to hexavalent chromium that will enable DoD to protect its assets. Field demonstration, licensing, qualification, and commercialization will allow its real world utilization.

Alternatives to Hexavalent Chromium, Controlled Re↗

NASA NTRSDate not supplied

Analysis of PICA-NuSil at the Hypersonic Materials Environmental Test System (HyMETS)

Phenolic Impregnated Carbon Ablator (PICA) gained heritage during theStardust mission and is the baseline thermal protection system (TPS) material for missions to Mars. However, PICA is friable, so a thin layer of siloxane resin (NuSil) is applied to the surface of the heat shield to suppress the spread of particulate matter during cleanroom activities. Until recently, the thermochemical response of NuSil had not been accounted for in material response models. Therefore, a test campaign was executed at the Hypersonic Materials Environmental Test System (HyMETS) facility to investigate the material response of NuSil and provide crucial insight for model development. Finally, salient results from an experiment supported by the AsteroidThreat Assessment Project (ATAP) will be discussed, which probed the materialr esponse of the Tamdakht meteorite and notable analogs.

Brody K. Bessire↗

NASA NTRS2013

Exploration Space Suit Architecture and Destination Environmental-Based Technology Development

This paper continues forward where EVA Space Suit Architecture: Low Earth Orbit Vs. Moon Vs. Mars1 left off in the development of a space suit architecture that is modular in design and could be reconfigured prior to launch or during any given mission depending on the tasks or destination. This paper addresses the space suit system architecture and technologies required based on human exploration (EVA) destinations, and describes how these systems should evolve to meet the future exploration EVA needs of the US human space flight program. A series of exercises and analyses provided a strong indication that the Constellation Program space suit architecture, with its maximum reuse of technology and functionality across a range of mission profiles and destinations, is postured to provide a viable solution for future space exploration missions. The destination environmental analysis demonstrates that the modular architecture approach could provide the lowest mass and mission cost for the protection of the crew, given any human mission outside of low-Earth orbit. Additionally, some of the high-level trades presented here provide a review of the environmental and non-environmental design drivers that will become increasingly important as humans venture farther from Earth. This paper demonstrates a logical clustering of destination design environments that allows a focused approach to technology prioritization, development, and design that will maximize the return on investment, largely independent of any particular design reference mission.

Hill, Terry R.↗

NASA NTRS2013

Exploration Space Suit Architecture and Destination Environmental-Based Technology Development

This paper continues forward where EVA Space Suit Architecture: Low Earth Orbit Vs. Moon Vs. Mars left off in the development of a space suit architecture that is modular in design and could be reconfigured prior to launch or during any given mission depending on the tasks or destination. This space suit system architecture and technologies required based on human exploration (EVA) destinations will be discussed, and how these systems should evolve to meet the future exploration EVA needs of the US human space flight program. A series of exercises and analyses provided a strong indication that the Constellation Program space suit architecture, with its maximum reuse of technology and functionality across a range of mission profiles and destinations, is postured to provide a viable solution for future space exploration missions. The destination environmental analysis demonstrates that the modular architecture approach could provide the lowest mass and mission cost for the protection of the crew, given any human mission outside of low-Earth orbit. Additionally, some of the high-level trades presented here provide a review of the environmental and nonenvironmental design drivers that will become increasingly important as humans venture farther from Earth. The presentation of destination environmental data demonstrates a logical clustering of destination design environments that allows a focused approach to technology prioritization, development, and design that will maximize the return on investment, largely independent of any particular design reference mission.

Hill, Terry R.↗

NASA NTRS2018

Next Steps in Planetary Protection for Human Spaceflight

Planetary protection is defined as: a) the prevention of contamination of extraterrestrial bodies by terrestrial microorganisms, and b) biohazard containment of returned samples from bodies in the Solar System that could harbor life.1 While the majority of interplanetary missions to date have involved robotic exploration, future missions will include human explorers. Current planetary protection requirements do not address the unique challenges associated with human exploration. The purpose of this abstract is to review planetary protection efforts for crewed missions and provide a forward plan for implementing them at the systems level. Article IX of the UN Outer Space Treaty of 1967 provides the definition of planetary protection, outlined above.1 COSPAR holds the international standard in line with this treaty2, while NASA's Planetary Protection Policy (NPD 8020.7G) outlines the U.S. implementation of the COSPAR standard. 3;4 NPI 8020.7 groups future human spaceflight planetary protection studies as follows: 1) microbial monitoring, 2) contamination mitigation and control, and 3) environmental effects. Additionally, a NPI 8020.7 outlines a five-step plan for forward work: 1) a literature review, 2) community inputs, 3) completion of recommended studies, 4) developing a draft NPR, and 5) implementation with NASA teams. The literature review was published in 2016.5 Inputs from the community were gathered at the Planetary Protection Knowledge Gaps for Human Extraterrestrial Missions, held in 2015.6 Johnson and Race (2016) outlined notional requirements and prioritized studies needed before final requirements can be produced. This prior work sets the stage for completing the necessary studies and finalizing planetary protection requirements for human spaceflight. We propose a continuation of the systems engineering approach adopted thus far. The challenges associated with the implementation of notional requirements will be quantified in detailed discussions with internal stakeholders. The status and results of high-priority studies that have been completed since 2016 or are ongoing will be incorporated into discussions with stakeholders. In this way, we plan to bridge the gap between the science behind planetary protection and the engineering development that will implement it, allowing finalized planetary protection requirements to be developed for future human space missions.

Mitchell, Julie↗

NASA NTRS2016

Advanced Environmental Barrier Coating Development for SiC/SiC Ceramic Matrix Composites: NASA's Perspectives

This presentation reviews NASA environmental barrier coating (EBC) system development programs and the coating materials evolutions for protecting the SiC/SiC Ceramic Matrix Composites in order to meet the next generation engine performance requirements. The presentation focuses on several generations of NASA EBC systems, EBC-CMC component system technologies for SiC/SiC ceramic matrix composite combustors and turbine airfoils, highlighting the temperature capability and durability improvements in simulated engine high heat flux, high pressure, high velocity, and with mechanical creep and fatigue loading conditions. The current EBC development emphasis is placed on advanced NASA 2700F candidate environmental barrier coating systems for SiC/SiC CMCs, their performance benefits and design limitations in long-term operation and combustion environments. Major technical barriers in developing environmental barrier coating systems, the coating integrations with next generation CMCs having the improved environmental stability, erosion-impact resistance, and long-term fatigue-environment system durability performance are described. The research and development opportunities for advanced turbine airfoil environmental barrier coating systems by utilizing improved compositions, state-of-the-art processing methods, and simulated environment testing and durability modeling are discussed.

Ceramic Matrix Composites↗

DOE OSTI2019

2018 Annual Site Environmental Report

Los Alamos National Laboratory’s (the Laboratory’s) annual site environmental reports are prepared annually by the Laboratory’s environmental organizations, as required by U.S. Department of Energy Order 231.1B, Administrative Change 1, Environment, Safety, and Health Reporting, and Order 458.1, Administrative Change 3, Radiation Protection of the Public and the Environment. The following chapters in this report discuss our success in complying with environmental laws, regulations, and orders (Chapter 2, Compliance Summary); how we manage the Laboratory’s environmental performance (Chapter 3, Environmental Programs); how we monitor for air emissions of radioactive materials and climate conditions (Chapter 4, Air Quality); how we monitor for effects of Laboratory operations on groundwater quality (Chapter 5, Groundwater Monitoring); how we monitor the movement of chemicals and radionuclides by storm water runoff and the levels of chemicals and radionuclides in deposited sediment (Chapter 6, Watershed Quality); how we monitor for the presence, levels, and effects of chemicals and radionuclides in plants, animals, soil, and vegetation (Chapter 7, Ecosystem Health); and finally, what radionuclide dose or risk from chemical exposure members of the public may experience as a result of Laboratory operations (Chapter 8, Public Dose and Risk Assessment). This report follows plain language guidelines, as required for federal agencies by the Plain Language Act of 2010. More information about plain language can be found at http://www.plainlanguage.gov/index.cfm. You will notice we have substantially reduced the use of acronyms and abbreviations and are using active voice and personal pronouns. We hope you find this report useful. If you have suggestions for improving this report, additional questions, or want a copy of this report, please contact us at envoutreach@lanl.gov, or call the Communications Office at 505-665-7000. This report, its supplemental tables, and the 2018 Annual Site Environmental Report Summary are available at http://www.lanl.gov/environment/environmental-report.php. Note: This document has been revised since it was initially published on September 23, 2019. The revisions included corrections to figure and table references, changes in heading levels, adding blank pages where appropriate, and changes of an editorial nature.

54 ENVIRONMENTAL SCIENCES↗

NASA NTRS1989

Space station protective coating development

A generic list of Space Station surfaces and candidate material types is provided. Environmental exposures and performance requirements for the different Space Station surfaces are listed. Coating materials and the processing required to produce a viable system, and appropriate environmental simulation test facilities are being developed. Mass loss data from the original version of the atomic oxygen test chamber and the improved facility; additional environmental exposures performed on candidate materials; and materials properties measurements on candidate coatings to determine the effects of the exposures are discussed. Methodologies of production, and coating materials, used to produce the large scale demonstration articles are described. The electronic data base developed for the contract is also described. The test chamber to be used for exposure of materials to atomic oxygen was built.

Pippin, H. G.↗