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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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24 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS2013

Green Solvents for Precision Cleaning

Aerospace machinery used in liquid oxygen (LOX) fuel systems must be precision cleaned to achieve a very low level of non-volatile residue (< 1 mg0.1 m2), especially flammable residue. Traditionally chlorofluorocarbons (CFCs) have been used in the precision cleaning of LOX systems, specifically CFC 113 (C2Cl3F3). CFCs have been known to cause the depletion of ozone and in 1987, were banned by the Montreal Protocol due to health, safety and environmental concerns. This has now led to the development of new processes in the precision cleaning of aerospace components. An ideal solvent-replacement is non-flammable, environmentally benign, non-corrosive, inexpensive, effective and evaporates completely, leaving no residue. Highlighted is a green precision cleaning process, which is contaminant removal using supercritical carbon dioxide as the environmentally benign solvent. In this process, the contaminant is dissolved in carbon dioxide, and the parts are recovered at the end of the cleaning process completely dry and ready for use. Typical contaminants of aerospace components include hydrocarbon greases, hydraulic fluids, silicone fluids and greases, fluorocarbon fluids and greases and fingerprint oil. Metallic aerospace components range from small nuts and bolts to much larger parts, such as butterfly valves 18 in diameter. A fluorinated grease, Krytox, is investigated as a model contaminant in these preliminary studies, and aluminum coupons are employed as a model aerospace component. Preliminary studies are presented in which the experimental parameters are optimized for removal of Krytox from aluminum coupons in a stirred-batch process. The experimental conditions investigated are temperature, pressure, exposure time and impeller speed. Temperatures of 308 - 423 K, pressures in the range of 8.3 - 41.4 MPa, exposure times between 5 - 60 min and impeller speeds of 0 - 1000 rpm were investigated. Preliminary results showed up to 86 cleaning efficiency with the moderate processing conditions of 323 K, 13.8 MPa, 30 min and 750 rpm.

solvents↗
NASA NTRS2014

Performing a Launch Depressurization Test on an Inflatable Space Habitat

In July, 2014 JPL's Environmental Test Laboratory successfully performed a launch depressurization test on an inflatable space habitat proposed to be installed on the International Space Station. The inflatable habitat is to be launched in the SpaceX Dragon Trunk. During the launch, the unpressurized Dragon Trunk will rapidly change from ground level atmospheric pressure to the vacuum of space. Since the inflatable habitat is tightly folded during launch with multiple layers of bladder, Kevlar fabric sections, and micro-meteoroid shielding, it was not possible to analyze or simulate how the residual air pockets would behave during the launch. If the inflatable habitat does not vent adequately and expands, it could rupture the payload bay of the launch vehicle. A launch depressurization test was chosen as the best way to qualify the inflatable habitat. When stowed, the inflatable habitat measured approximately 241 cm (95 inches) in diameter by 152 cm (60 inches) high and weighed close to 1361 kg (3,000 pounds). Two vacuum chambers connected by a large vacuum line were used to perform this test. The inflatable habitat was mounted in the smaller chamber, which was 396 cm (13 feet) in diameter and 1128 cm (37 feet) high. The larger chamber, which was 823 cm (27 feet) in diameter and 2,591 cm (85 feet) high, was rough pumped and used as a vacuum reservoir. A two stage axial type compressor and ten Stokes vacuum pumps were also used during the depressurization. Opening a butterfly valve on the vacuum line, at the smaller chamber, was manually controlled so that the smaller chamber's depressurization rate matched the launch pressure profile.

ETL↗
NASA NTRS1996

Remote manual operator for space station intermodule ventilation valve

The Remote Manual Operator (RMO) is a mechanism used for manual operation of the Space Station Intermodule Ventilation (IMV) valve and for visual indication of valve position. The IMV is a butterfly-type valve, located in the ventilation or air circulation ducts of the Space Station, and is used to interconnect or isolate the various compartments. The IMV valve is normally operated by an electric motor-driven actuator under computer or astronaut control, but it can also be operated manually with the RMO. The IMV valve RMO consists of a handle with a deployment linkage, a gear-driven flexible shaft, and a linkage to disengage the electric motor actuator during manual operation. It also provides visual indication of valve position. The IMV valve RMO is currently being prepared for qualification testing.

Guyaux, James R.↗
NASA NTRS1975

Long life valve design concepts

Valve concept evaluation, final candidate selection, design, manufacture, and demonstration testing of a pneumatically actuated 10-inch hybrid poppet butterfly shutoff valve are presented. Conclusions and recommendations regarding those valve characteristics and features which would serve to guide in the formulation of future valve procurements are discussed. The pertinent design goals were temperature range of plus 200 to minus 423 F, valve inlet pressure 35 psia, actuation pressure 750 psia, main seal leakage 3 x 0.00001 sccs at 35 psia valve inlet pressure, and a storage and operating life of 10 years. The valve was designed to be compatible with RP-1, propane, LH2, LO2, He, and N2.

Jones, J. R.↗
NASA NTRS1991

Lightweight Valve Closes Duct Quickly

Expanding balloon serves as lightweight emergency valve to close wide duct. Uninflated balloon stored in housing of duct. Pad resting on burst diaphragm protects balloon from hot gases in duct. Once control system triggers valve, balloon inflates rapidly to block duct. Weighs much less than does conventional butterfly, hot-gas, or poppet valve capable of closing duct of equal diameter.

Fournier, Walter L.↗
DOE OSTI2023

Adaptations for gas exchange enabled the elongation of lepidopteran proboscises

The extensive biodiversification of butterflies and moths (Lepidoptera) is partly attributed to their unique mouthparts (proboscis [Pr]) that can span in length from less than 1 mm to over 280mm in Darwin's sphinx moths. Lepi-doptera, similar to other insects, are believed to inhale and exhale respiratory gases only through valve-like spi-racles on their thorax and abdomen, making gas exchange through the narrow tracheae (Tr) challenging for the elongated Pr. How Lepidoptera overcome distance effects for gas transport to the Pr is an open question that is important to understanding how the Pr elongated over evolutionary time. Here, we show with scanning electron microscopy and X-ray imaging that distance effects on gas exchange are overcome by previously unreported micropores on the Pr surface and by superhydrophobic Tr that prevent water loss and entry. We find that the density of micropores decreases monotonically along the Pr length with the maxima proportional to the Pr length and that micropore diameters produce a Knudsen number at the boundary between the slip and transition flow regimes. By numerical estimation, we further show that the respiratory gas exchange for the Pr predominantly occurs via diffusion through the micropores. In conclusion, these adaptations are key innovations vital to Pr elongation, which likely facilitated lepidopteran biodiversification and the radiation of angiosperms by coevolutionary processes.

59 BASIC BIOLOGICAL SCIENCES↗