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Particle Dispersion System for Microgravity Environments

Completed Technology Project

Project Introduction

Particle Dispersion System for Microgravity Environments
Many scientific disciplines, engineering applications, and industrial pursuits involve the study or handling of particulate matter occurring in the form of powders and granules. In most cases, there is a need to be able to predict the behavior of these materials, and this in turn requires knowledge of the fundamental physics that causes particles to attract or repel one another. Our long-term goal is to experimentally approach the physics with a multi-parameter matrix including Coulombic, thermal, radiation, pressure, and other variables. We will study these materials while they are freely suspended and dispersed in reduced gravity (in order to unmask weak forces). In the short term, to which this proposal refers, we have to address the technical challenge of initializing an experiment by first dispersing particulates in a test chamber, then maintaining this dispersion without the material being lost to the chamber walls by adhesion. This is technically non-trivial as we have experienced with particulate dispersions on Space Shuttle (USML-1&2). We have fabricated and tested a mechanically robust vibrational apparatus, the Particle Dispersion System (PDS) that can perform the dual function of initial dispersion and maintenance of particle-free walls. It is a mechanically straightforward system with a 2-axis variable vibrator mechanism mechanically coupled to the walls of a small sealed dispersion chamber. The chamber will be internally illuminated and viewed through a window with a fixed position video recorder. We will record how grains are ejected from the walls and how the walls are kept grain-free as well as the trajectories and interaction of the grains when they are in the free space of the chamber. Because the vibration will triboelectrically charge the grains in the process of dispersing them, we will also plan to use this technique for initializing experiments to study electrostatic grain interactions (in the future, we will vary the type of coating on the walls so that it will be possible to control the polarity on the charged grains). The PDS is at TRL4 insofar as it has demonstrated the ability to eject a variety of particulates from the vessel walls even under normal gravity conditions. To determine the efficacy of this technology for creating and maintaining a particulate dispersion in the free space away from the walls, it must be tested in an appropriate reduced gravity environment. We are proposing to test it with a series of parabolic aircraft flights. In the weightless parabolic flight environment, the multiple parabolas as well as multiple flights will enable the testing of a series of variables that affect particle dispersion and electrostatic charging, viz, the intensity of the wall vibration, vibration frequency, vibration duration, particle size and shape, particle elasticity, and dispersed cloud density. Observations recorded on video will include dispersal efficiency, maintenance of particle-free walls, particle trajectories (direction and speed), and particle interactions such as the formation of aggregates. More »

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Technology Maturity (TRL)

Target Destination

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