Engineering topics

Fester, D. A.

Publications and source records attributed to Fester, D. A..

32 records · Page 2

NASA NTRS1977

Behavior of fluids in a weightless environment

Fluid behavior in a low-g environment is controlled primarily by surface tension forces. Certain fluid and system characteristics determine the magnitude of these forces for both a free liquid surface and liquid in contact with a solid. These characteristics, including surface tension, wettability or contact angle, system geometry, and the relationships governing their interaction, are discussed. Various aspects of fluid behavior in a low-g environment are then presented. This includes the formation of static interface shapes, oscillation and rotation of drops, coalescence, the formation of foams, tendency for cavitation, and diffusion in liquids which were observed during the Skylab fluid mechanics science demonstrations. Liquid reorientation and capillary pumping to establish equilibrium configurations for various system geometries, observed during various free-fall (drop-tower) low-g tests, are also presented. Several passive low-g fluid storage and transfer systems are discussed. These systems use surface tension forces to control the liquid/vapor interface and provide gas-free liquid transfer and liquid-free vapor venting.

Fester, D. A.↗

NASA NTRS1976

Evaluation of fluid behavior in spinning toroidal tanks

An experimental study was conducted to evaluate propellant behavior in spinning toroidal tanks that could be used in a retro-propulsion system of an advanced outer-planet Pioneer orbiter. Information on propellant slosh and settling and on ullage orientation and stability was obtained. The effects of axial acceleration, spin rate, spin rate change, and spacecraft wobble, both singly and in combination, were evaluated using a 1/8-scale transparent tank in one-g and low-g environments. Liquid loadings ranged from 5% to 96% full. The impact of a surface tension acquisition device was assessed. Testing simulated the behavior of F2/N2H4 and N2O4/MMH propellants. Results are presented which indicate no major fluid behavior problems would be encountered with any of the four propellants in the toroidal tanks of a spin-stabilized orbiter spacecraft.

Anderson, J. E.↗

NASA NTRS1975

Surface tension propellant acquisition system technology for Space Shuttle reaction control tanks

A program was conducted to provide the technology base for the SS/RCS flight tankage. Through a combination of analysis, subscale testing and computer predictions, a surface tension acquisition/expulsion system design was developed for the Orbiter RCS application. A full-scale tank system was fabricated and ground verification testing was conducted. Cleaning, inspection, fill and drain, and one-g expulsion performance were demonstrated. Results show that the fine-mesh screen, compartmented tank system provides the performance, flexibility, reusability, and other characteristics required by the pulsing, high flowrate RCS. It provides the required expulsion under widely differing high-g boost abort and reentry vectors oriented 119 deg apart and during on-orbit operation under omnidirectional low-g conditions.

Fester, D. A.↗

NASA NTRS1975

Measurements of capillary system degradation

The effects of vibration, flow transients, and warm gas pressurization on capillary acquisition system performance were evaluated. The degradation observed under wide band random and high frequency sinusoidal vibration was of a substantially different nature from that obtained under low frequency sinusoidal vibration. With the former, ingestion of small gas bubbles into the liquid region was correlated by a hydrostatic model, while the capillary stability was destroyed and liquid was lost from the liquid region with the latter. No degradation was observed as a result of flow transients in a flight-type multichannel screen device, but it was observed in a transparent laboratory device. Liquid hydrogen outflow tests were conducted with a multilayer dual-screen-liner system with both helium and hydrogen pressurant gases. The tendency towards dryout of the device with hydrogen pressurant was found to increase with increasing pressurant temperature and length of prepressurization period. Dryout did not occur with helium pressurant.

Warren, R. P.↗

NASA NTRS1974

Space Shuttle Reaction Control Subsystem propellant acquisition

A surface tension propellant acquisition/expulsion configuration was selected for the Space Shuttle Reaction Control Subsystem tankage to supply gas-free propellant during the low- and high-g operational environment (.00001 to 3.0 g) plus the numerous omnidirectional intermittent (pulse) demands of each mission. Candidate concepts to meet these stringent requirements were identified; this was followed by analysis and design sensitivity evaluations. A trade study resulted in the selection of a compartmented tank with individual flow channels as the preferred concept. Details of the analysis and design are presented.

Fester, D. A.↗

NASA NTRS1974

Space storable propellant acquisition system

A program was conducted to select the best surface tension propellant acquisition concept for an advanced 3-axis spacecraft propulsion system having 10-year life. Fabricability, performance capability, and spacecraft compatibility of various candidate concepts were assessed and compared. The results showed the sheet-metal vane low-g systems to be preferred for these interplanetary applications. They can be adapted to a broad spectrum of low-g applications and can be tailored to specific missions with the desired operational margin. A preliminary standpipe with vanes design was accomplished based on analysis and testing of the more significant factors influencing fabrication and operation.

Tegart, J. R.↗

NASA NTRS1974

A feasibility study of developing toroidal tanks for a spinning spacecraft

The use of toroidal tanks in an advanced Pioneer, spin-stabilized Jupiter orbiter was investigated. Fluid behavior in spinning toroids was evaluated and the need for a propellant acquisition system was established. A common surface tension acquisition system design was selected from four candidates for gas-free liquid feed to a single outlet in both MMH and N2O4 tanks. Fabrication of toroidal tanks using either titanium or aluminum alloys is feasible. Integration of two toroidal tanks with surface tension systems in place of four spherical tanks provides spacecraft weight, packaging, structural mounting, thermal control and stability advantages.

Anderson, J. E.↗

NASA NTRS1973

A feasibility study of developing toroidal tanks for a spinning spacecraft

A study was made to determine the feasibility of developing toroidal propellant tanks for a bipropellant (N204/MMH) propulsion system to be used in a proposed advanced Pioneer spin-stabilized vehicle intended for a Jupiter-orbiter and possibly a Saturn-orbiter mission. The rationale for considering the use of two toroidal tanks rather than the proposed use of four spherical tanks includes the belief that a more symmetrical distribution of propellant mass and a smaller variation in the position of the vehicle center-of-mass during propellant consumption would result, reducing requirements for attitude-control propellants, for balance weight, and for other weights associated with the dynamics of the spinning spacecraft. Results lead to the conclusion that a toroidal tank containing an effective, passive surface tension propellant acquisition device could be fabricated with available manufacturing methods and could be used interchangeably for either fuel or oxidizer.

Anderson, J. E.↗

NASA NTRS1972

Space storable propellant acquisition system

Surface tension propellant acquisition concepts for an advanced spacecraft propulsion system having a 10-year mission capability were investigated. Surface tension systems were specified because they were shown to be the best propellant acquisition technique for various interplanetery spacecraft in a prior study. A variety of surface tension concepts for accomplishing propellant acquisition were formulated for the baseline space storable propulsion module and Jupiter Orbiter mission. Analyses and evaluations were then conducted on each candidate concept to assess fabricability, performance capability, and spacecraft compatibility. A comparative evaluation of the results showed the Fruhof-class of low-g surface tension systems to be preferred for these interplanetary applications.

Tegart, J. R.↗

NASA NTRS1972

Material Compatibility with Space Storable Propellants. Design Guidebook

An important consideration in the design of spacecraft for interplanetary missions is the compatibility of storage materials with the propellants. Serious problems can arise because many propellants are either extremely reactive or subject to catalytic decomposition, making the selection of proper materials of construction for propellant containment and control a critical requirement for the long-life applications. To aid in selecting materials and designing and evaluating various propulsion subsystems, available information on the compatibility of spacecraft materials with propellants of interest was compiled from literature searches and personal contacts. The compatibility of both metals and nonmetals with hydrazine, monomethyl hydrazine, nitrated hydrazine, and diborance fuels and nitrogen tetroxide, fluorine, oxygen difluoride, and Flox oxidizers was surveyed. These fuels and oxidizers encompass the wide variety of problems encountered in propellant storage. As such, they present worst case situations of the propellant affecting the material and the material affecting the propellant. This includes material attack, propellant decomposition, and the formation of clogging materials.

Uney, P. E.↗

NASA NTRS1971