Index to nasa tech briefs, issue number 2

Annotated bibliography on technological innovations in NASA space program

DEM investigation of the influence of particulate properties and operating conditions on the mixing process in rotary drums: Part 1-Determination of the DEM parameters and calibration process

This paper's goal was to select methods and a calibration procedure which would lead to the determination of relevant parameters of a discrete element method (DEM) and virtual material creation. Seven particulates were selected with respect to their shape (spherical and non-spherical), size and density. The first calibration experiment involved "packing test" to determine the shape accuracy and bulk density of virtual packed particulates. The series of simulations were compared with real experiments, and the size, shape and density of virtual particles were optimized. Using three apparatuses, the input parameter values were experimentally determined for a contact model that defines the behavior of particulates in DEM simulations. The research part of the paper examines the influence of factors such as particle number; pile formation method; and the method of evaluation of the angle of repose on the process of the calibration of virtual material. The most reproducible results were achieved by the "pilling" method and by the rotating drum-both evaluated by the geometric method. However, it is always advisable to make an overall visual comparison of the slope shape between the calibration simulation and the experimental curves. The bowl's diameter to particle size ratio should be greater than 25, and the calibration experiment should contain approximately 4000 particles to ensure representative results during angle of repose calibration experiment.Web of Science82art. no. 22

Hydrodynamic effects on soiled surfaces : an experimental study and theoretical analysis

This thesis presents the findings of an investigation aimed at understanding the effects of hydrodynamic shear stress on soil removal from textile surfaces both inside the washing machine and in closely controlled laboratory conditions. The research has involved developing a technique for the indirect measurement of shear stress based on pressure recordings and small block probes that provide both an indication of shear stress magnitude and direction. The probes have been investigated and calibrated in a purpose-built, rectangular-section, water tunnel in which tests were also carried out on specially prepared soiled cotton textile samples. This has allowed the correlation between shear stress and soil removal efficiency for 15k ≤ Re ≤ 155k. A more general investigation involving the washing machine has also been carried out so as to quantify and compare the effects of detergency, water temperature, time, abrasion, warping and tangential shear force. The hydrodynamic conditions inside the washing machine were investigated providing insight into flow conditions both on the inside and outside of the wash load. This was achieved through the use of a wireless device in the form of a sphere with an on-board pressure-flow sensor and radio transmitter for remote monitoring via radio. This remote data acquisition system was designed, developed and patented by the author. A model of the wash load motion has also been developed and high speed filming techniques employed to qualify and quantify the wash load dynamics. The main outcome of the research may be summarised as follows: - Hydrodynamic shear stress up to 7.7Pa a circa (15k ≤ Re ≤ 155k) is inadequate to remove soil from the standard EMPA textile surfaces. - Only 10-15% of the soil removed in the washing machines can be attributed to abrasion, warping (due to churning) and hydrodynamic shear stress, the rest is attributed to detergency and heat transfer. - There are at least two different flow domains within a horizontal-axis washing machine, one on the inside of the wash load and one on the outside. - Flow conditions on both the inside and outside are turbulent and velocities up to several meters per second have been recorde

Physics of windblown particles

A laboratory facility proposed for the Space Station to investigate fundamental aspects of windblown particles is described. The experiments would take advantage of the environment afforded in earth orbit and would be an extension of research currently being conducted on the geology and physics of windblown sediments on earth, Mars, and Venus. Aeolian (wind) processes are reviewed in the planetary context, the scientific rational is given for specific experiments to be conducted, the experiment apparatus (the Carousel Wind Tunnel, or CWT) is described, and a plan presented for implementing the proposed research program

NASA Tech Briefs Index, 1977, volume 2, numbers 1-4

Announcements of new technology derived from the research and development activities of NASA are presented. Abstracts, and indexes for subject, personal author, originating center, and Tech Brief number are presented for 1977

Space Station Planetology Experiments (SSPEX)

A meeting of 50 planetary scientists considered the uses of the Space Station to support experiments in their various disciplines. Abstracts (28) present concepts for impact and aeolian processes, particle formation and interaction, and other planetary science experiments. Summaries of the rationale, hardware concepts, accomodations, and recommendations are included

Automatic controls and regulators: A compilation

Devices, methods, and techniques for control and regulation of the mechanical/physical functions involved in implementing the space program are discussed. Section one deals with automatic controls considered to be, essentially, start-stop operations or those holding the activity in a desired constraint. Devices that may be used to regulate activities within desired ranges or subject them to predetermined changes are dealt with in section two