Engineering topics

Alred, J. W.

Publications and source records attributed to Alred, J. W..

4 records

NASA NTRS1991

Lunar hydrogen extraction

This paper examines the power and mass requirements of a lunar hydrogen extraction plant producing five metric tons of hydrogen per year. These power and mass requirements are based upon experimental work that determined gaseous hydrogen release rates from lunar samples at various heating rates and temperatures. An optimum heating temperature and rate can be selected to minimize the processing plant's power and mass requirements. The impact of thermal recovery on the power and mass requirements is studied, as is the use of nuclear waste heat for processing the regolith. In addition, the potential of using the extracted hydrogen in the form of methane as a propellant for a Lunar Excursion Vehicle is examined.

Snaufer, M. J.↗

NASA NTRS1986

An in-situ measurement of particulates from solid rocket motors fired in space

Current models exist that predict the damage caused by the impact of aluminum oxide exhaust particles as well as their lifetime in useable space. In these models, two necessary inputs are the size and flux of the particles. An experiment, referred to as the Plume Witness Plate, was designed for the Remote Manipulator System of the space shuttle orbiter to measure in-situ the flux and material effects of a solid rocket motor (SRM) firing in space. Five different types of samples were used to provide a broad range of substances: (1) fused quartz glass (representative of orbiter windows); (2) germanium micrometeroid capture cells; (3) orbiter HRTS tiles from the thermal protection system; (4) Kapton foil; and (5) metallic disks of aluminum, copper, titanium, graphite epoxy, and gold. The analyses of the data show excellent agreement with ground-based SRM firings in terms of particle size distribution and mass distribution. The Particle Impact Damage Integrator computer model used to calculate potential damage of orbiter surfaces by SRM exhaust plumes agrees favorable with the results in terms of particle size and velocity distributions though it may be conservative by as much as 20%.

Alred, J. W.↗

NASA NTRS1985

Results of the SPAS-01 RCS plume impingement test

The Orbiter RCS flowfield is modeled in the free molecular region and an impingement analysis is performed to characterize on-orbit plume interactions with nearby bodies, such as the SPAS-01 satellite. The flow in the far field is treated with a source flow model at any point 40 ft from the nozzle. Impingement is calculated according to Newtonian impact theory. The flow density in the far field is expressed in terms of a conservation of energy equation, with account taken of the expansion of the gas, cooling, and the angular distribution. The SPAS-01 platform gathered data at eight different positions around the Orbiter to test the model predictions. Excellent agreement was obtained in predictions of the torque and rotation rate induced on the SPAS by firing the thrusters.

Lazaron, M. P.↗

NASA NTRS1983

Flow field description for the reaction control system of the Space Shuttle Orbiter

The flow field for the Reaction Control System (RCS) jets of the Space Shuttle Orbiter has been calculated from the nozzle throat to the far-field flow region. The calculations involved the use of recently improved rocket engine nozzle/plume codes and the source flow analytic model. The flow solution is discussed and used to produce impingement forces and moments for surfaces immersed in the flow. The impingement results are compared to calculations involving previous flow solutions in order to evaluate the impingement effects due to the RCS jets during orbital operations.

Alred, J. W.↗