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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 1,189 records · Page 66
All sourcesNASA NTRSDOE OSTI
NASA NTRS1988

Design, development, and test of Shuttle/Centaur G-prime cryogenic tankage thermal protection systems

The thermal protection systems (TPS) for the Shuttle/Centaur were designed to provide fail-safe thermal protection during prelaunch, launch ascent, and on-orbit operations as well as during potential abort, where the Shuttle and Centaur would return to earth. The TPS selected used a helium-purged polyimide foam beneath three radiation shields for the liquid-hydrogen (LH2) tank and radiation shields only for the liquid-oxygen (LO2) tank. A double-walled vacuum bulkhead separated the two tanks. The LH2 tank had one 1.9 cm-thick layer of foam on the forward bulkhead and two layers on the larger-area sidewall. Full scale tests of the flight vehicle in a simulated Shuttle cargo bay gave total prelaunch heating rates of 29.5 and 12.9 kW for the LH2 and LO2 tanks, respectively. Calorimeter tests on a representative sample of the LH2 tank sidewall TPS indicated that the measured unit heating one would rapidly decrease from the prelaunch rate of about 300 W/sq m to a desired rate less than 4 W/sq m once on-orbit.

Macneil, Peter N.↗
NASA NTRS1989

Microsandwich Honeycombs

In new type of honeycomb panel called "microsandwich honeycomb," walls filled with solid plastic foam reinforced with microspheres. Have compressive and shear strengths 50 to 70 percent greater than those of conventional, unfilled honeycombs of comparable dimensions and densities. Foam and hollow microspheres add little to weight but increase strength substantially. Useful in aircraft, automotive, and marine structures in which high strength and low weight important.

Bhat, Balakrishna↗
NASA NTRS1989

Consort 1 sounding rocket flight

This paper describes a payload of six experiments developed for a 7-min microgravity flight aboard a sounding rocket Consort 1, in order to investigate the effects of low gravity on certain material processes. The experiments in question were designed to test the effect of microgravity on the demixing of aqueous polymer two-phase systems, the electrodeposition process, the production of elastomer-modified epoxy resins, the foam formation process and the characteristics of foam, the material dispersion, and metal sintering. The apparatuses designed for these experiments are examined, and the rocket-payload integration and operations are discussed.

Wessling, Francis C.↗
NASA NTRS1992

Cryogenic storage technology readiness for First Lunar Outpost

The topics are presented in viewgraph form and include the following: an assessment of cryogenic storage technology; cryogenic boiloff predictions; Space Shuttle/Centaur thermodynamic vent system; zero-g thermodynamic vent system; heat exchanger/mixer pump module; the thick multilayer insulation (MLI) development program; blanket geometry concept evaluations; four-inch thick MLI system on 1/4-scale test tank; combined environments of vibration, acceleration, and temperature testing (CEVAT); Centaur fixed foam insulation; insulation system design; and fixed foam on operational Atlas 2.

John R. Schuster↗
NASA NTRS1991

Evolution of bioconvective patterns in variable gravity

Measurements are reported of the evolution of bioconvective patterns in shallow, dense cultures of microorganisms subjected to varying gravity. Various statistical properties of this random, quasi-two-dimensional structure have been found: Aboav's law is obeyed, the average vertex angles follow predictions for regular polygons, and the area of a pattern varies linearly with its number of sides. As gravity varies between 1 g and 1.8 g, these statistical properties continue to hold despite a tripling of the number of polygons and a reduced average polygon dimension by a third. This work compares with experiments on soap foams, Langmuir monolayer foams, metal grains, and simulations.

Noever, David A.↗
NASA NTRS1993

Modifications Of A Commercial Spray Gun

Commercial spray gun modified to increase spray rate and make sprayed coats more nearly uniform. Consists of gun head and pneumatic actuator. Actuator opens valves for two chemical components, called "A" and "B," that react to produce foam. Components flow through orifices, into mixing chamber in head. Mixture then flows through control orifice to spray tip. New spray tip tapered to reduce area available for accumulation of foam and makes tip easier to clean.

Allen, Peter B.↗
NASA NTRS1993

Experimental Observations of the Effect of Gravity Changes on Smoldering Combustion

The effects of gravity changes on the natural convection smolder characteristics of flexible polyurethane foam were determined in order to provide information on the potential onset of a smolder-initiated fire in a space-based facility. Experiments were conducted in an aircraft following parabolic trajectories providing up to 25 seconds of low gravity. Temperature histories of polyurethane foam were measured at several locations along the fuel sample interior. Results are presented and discussed for both upward and downward smoldering. Results indicate that gravity significantly effects the competition between supply of oxidizer to, and the transfer of heat to and from the reaction zone. This competition determines the characteristics of the smolder reaction. Within the reaction zone the reduction in oxygen supply in low gravity is dominant and the reaction weakens. Away from the reaction zone the reduction in convective cooling at low gravity tends to increase the material temperature. The opposite was observed at high gravity.

Torero, J. L.↗
NASA NTRS1993

Monolithic catalytic igniters

Catalytic igniters offer the potential for excellent reliability and simplicity for use with the diergolic bipropellant oxygen/hydrogen as well as with the monopropellant hydrazine. State-of-the-art catalyst beds - noble metal/granular pellet carriers - currently used in hydrazine engines are limited by carrier stability, which limits the hot-fire temperature, and by poor thermal response due to the large thermal mass. Moreover, questions remain with regard to longevity and reliability of these catalysts. In this work, Ultramet investigated the feasibility of fabricating monolithic catalyst beds that overcome the limitations of current catalytic igniters via a combination of chemical vapor deposition (CVD) iridium coatings and chemical vapor infiltration (CVI) refractory ceramic foams. It was found that under all flow conditions and O2:H2 mass ratios tested, a high surface area monolithic bed outperformed a Shell 405 bed. Additionally, it was found that monolithic catalytic igniters, specifically porous ceramic foams fabricated by CVD/CVI processing, can be fabricated whose catalytic performance is better than Shell 405 and with significantly lower flow restriction, from materials that can operate at 2000 C or higher.

La Ferla, R.↗
NASA NTRS1994

Improved Helmet-Padding Material

Polyimide foamed into lightweight padding material for use in helmets. Exhibits increased resistance to ignition, combustion, and impact, and it outgasses less. Foam satisfies offgassing and toxicity requirements of NASA/JSC criteria (NHB80601B). Helmets containing this improved padding material used by firefighters, police, offshore drilling technicians, construction workers, miners, and race-car drivers.

Dawn, Frederic S.↗
NASA NTRS1994

Self-Calibrating, Variable-Flow Pumping System

Pumping system provides accurate, controlled flows of two chemical liquids mixed in spray head and react to form rigid or flexible polyurethane or polyisocyanurate foam. Compatible with currently used polyurethane-based coating materials and gas-bubble-forming agents (called "blowing agents" in industry) and expected to be compatible with materials that used in near future. Handles environmentally acceptable substitutes for chlorofluorocarbon foaming agents.

Walls, Joe T.↗
NASA NTRS1993

Features of a SINDA/FLUINT model of a liquid oxygen supply line

The modeling features used in a steady-state heat transfer problem using SINDA/FLUINT are described. The problem modeled is a 125 feet long, 3 inch diameter pipe, filled with liquid oxygen flow driven by a given pressure gradient. The pipe is fully insulated in five sections. Three sections of 1 inch thick spray-on foam and two sections of vacuum jacket. The model evaluates friction, turns losses and convection heat transfer between the fluid and the pipe wall. There is conduction through the foam insulation with temperature dependent thermal conductivity. The vacuum space is modeled with radiation and gas molecular conduction, if present, in the annular gap. Heat is transferred between the outer surface and surrounding ambient by natural convection and radiation; and, by axial conduction along the pipe and through the vacuum jacket spacers and welded seal flanges. The model makes extensive use of SINDA/FLUINT basic capabilities such as the GEN option for nodes and conductors (to generate groups of nodes or conductors), the SIV option (to generate single, temperature varying conductors), the SIM option (for multiple, temperature varying conductors) and the M HX macros for fluids (to generate strings of lumps, paths, and ties representing a diabatic duct). It calls subroutine CONTRN (returns the relative location in the G-array of a network conductor, given an actual conductor number) enabling an extensive manipulation of conductor (calculates an assignment of their values) with DO loops. Models like this illustrate to the new and even to the old SINDA/FLUINT user, features of the program that are not so obvious or known, and that are extremely handy when trying to take advantage of both, the automation of the DATA headers and make surgical modifications to specific parameters of the thermal or fluid elements in the OPERATIONS portion of the model.

Simmonds, Boris G.↗
NASA NTRS1994

Cryogenic insulation studies

The following are discussed: CPR-488/141-B problem (CPR XUS); CPR XUS foam popcorning (wind tunnel test); BX-250/141-B spray problem; NCFI 24-57 (NCFI-141B); PDL 4034/141B pour foam; primer for ET; and potential TMCPP toxic problem.

Stuckey, James M.↗
NASA NTRS1994

Physics of spacecraft-based interplanetary dust collection by impact into low-density media

A spacecraft encountering an interplanetary dust particle (IDP) at a relative velocity of several kilometers per second may be used to capture that particle for in situ analysis or for analysis upon Earth return. In this paper we study the impact of a dust particle into a low-density medium (i.e., a foam) such that the foam dissipates the kinetic energy of impact over a sufficient distance to stop the particle without destroying it.

Anderson, William W.↗
NASA NTRS1994

Laboratory simulation of intact capture of cometary and asteroidal dust particles in ISAS

In order to develop a collector for intact capturing of cometary dust particles in the SOCCER mission and regolith dust particles released from asteroid surfaces by the impact of projectiles launched from a flying-by spacecraft, various kinds of materials as the collector candidates have been exposed to hypervelocity projectiles in our laboratory. Data based on the penetration characteristics of various materials (penetration depth, hole profile, effectiveness for intact capturing) are greatly increased. The materials tested for these simulation experiments include various kinds of low-density media and multisheet stacks; these are foamed plastics (polystyrene 0.01 g/cc), silica aerogels (0.04 g/cc), air (0.001 g/cc), liquid, and multisheet stack consisting of thin Al sheets (thickness 0.002 to 0.1 mm) or polyethylene sheets. Projectiles used are spheres or cylinders of nylon, polycarbonate, basalt, copper, iron, and volatile organics (e.g.,paradichlorobenzene) of size ranging from 30 micrometers to 1 cm launched by a two-stage light gas gun and a rail gun in ISAS at velocity up to about 7 km/s. Some results obtained by using nylon projectiles of velocity less than about 5 km/s are presented; the penetration depth vs. bulk density of the collector material for several kinds of materials and the velocity at which the projectiles begin to fragment vs. material density for foamed polystyrene.

Fujiwara, A.↗
NASA NTRS1994

Experimental observations of the effect of gravity changes on smoldering combustion

An experimental study is conducted to determine the effect of gravity changes on the natural convection smolder characteristics of flexible polyurethane foam. Gravity, and consequently buoyancy, is expected to affect smoldering because it induces convective transport of mass and heat to and from the reaction zone. The overall objective of the work is to provide information about the potential onset of a smolder-initiated fire in a space-based facility. Experiments are conducted in an aircraft following parabolic trajectories that provide up to 25 s of low gravity (KC-135A) and up to 20 s (Learjet Model 25), with a pull-up and pull-out of approximately 2 g per parabola. Measurements are performed, during a series of parabolas, of the temperature histories of the polyurethane foam at several locations along the fuel sample interior, both for upward and downward propagation. The measurements show that gravity plays a significant role in the competition between the supply of oxidizer to, and the transfer of heat to and from, the reaction zone.

Torero, J. L.↗
NASA NTRS1995

Device Would Provide Controllable Buoyancy

Proposed buoyant device attaches to object denser than water and adjusts to obtain neutral overall buoyancy. Conceived to aid training astronauts in handling "weightless" equipment in water tanks. Could be used to support marine environmental monitoring instrument at fixed predetermined depth. In marine salvage operation it holds parts at convenient depth before used or hoisted to surface. Device made in variety of sizes and shapes to suit objects to be supported. Could be equipped with such suitable attachment hardware as U-bolts, clamps, or cable ties. One or more such devices used to support object as necessary. Replaces plastic foam floats, which must be cut to size according to estimates of volume of foam that gives required amount of buoyancy. Device does not become waterlogged or release contaminating particles.

Macmartin, Malcolm J.↗
NASA NTRS1994

Development and Qualification of Alternate Blowing Agents for Space Shuttle External Tank Thermal Protection System

The Aerospace industry has a long history of using low density polyurethane and polyurethane-modified isocyanurate foam systems as lightweight, low cost, easily processed cryogenic Thermal Protection Systems (TPS) for ascent vehicles. The Thermal Protection System of the Space Shuttle External Tank (ET) is required so that quality liquid cryogenic propellant can be supplied to the Orbiter main engines and to protect the metal structure of the tanks from becoming too hot from aerodynamic heating, hence preventing premature break-up of the tank. These foams are all blown with CFC-1 I blowing agent which has been identified by the Environmental Protection Agency (EPA) as an ozone depleting substance. CFCs will not be manufactured after 1995, Consequently, alternate blowing agent substances must be identified and implemented to assure continued ET manufacture and delivery. This paper describes the various testing performed to select and qualify HCFC-1 41 b as a near term drop-in replacement for CFC-11. Although originally intended to be a one for one substitution in the formulation, several technical issues were identified regarding material performance and processability which required both formulation changes and special processing considerations to overcome. In order to evaluate these material changes, each material was subjected to various tests to qualify them to meet the various loads imposed on them during long term storage, pre-launch operations, launch, separation and re-entry. Each material was tested for structural, thermal, aeroshear, and stress/strain loads for the various flight environments each encounters. Details of the development and qualification program and the resolution of specific problems are discussed in this paper.

Williams, Charles W.↗
NASA NTRS1997

W-Band Transmission MeasurementS and X-Band Dielectric Properties Measurements for a Radome Material Sample

This paper describes measurements which were performed on a sample of radome material in the Electromagnetic Properties Measurements Laboratory (EPML). The purpose of the measurements described in this paper was to determine the one-way transmission loss through the flat panel of radome material for a frequency range of 84 to 94 GHz, for varying incidence angles. The panel, which was manufactured by Norton Performance Plastics Corporation, was provided to the EPML by TRW. The size of the panel is 40 in x 36 in x 0.422 in and consists of a foam material with one side coated with a smooth white coating (this side will be referred to as the front side). The dielectric properties of the foam material from the inside of the panel were also determined at X-band (8.2-12.4 GHz). The W-band free space measurements are presented first, followed by the X-band dielectric properties measurements.

Cravey, Robin L.↗