Aerospace Engineering Research Works

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    Experimental Demonstration and Quantification of Electrostatic Lofting of Dust Clumps
    (2023) Pett, Charles; Hartzell, Christine; Hartzell, Christine
    Electrostatic lofting of individual regolith grains on the Moon and asteroids has been investigated extensively. However, motion of clumps has been mentioned only anecdotally. For the first time, we electrostatically lofted clumps of 200-300 micrometer zirconia-silica microspheres in vacuum and quantitatively analyzed their trajectories. The microspheres were charged by an emissive filament. A biased plate produced an electric field of 870 kV/m that attracted sufficiently charged clumps from the surface. A high-speed camera imaged the lofted clumps at 945 fps in order to obtain their size and centroid positions over time. Using the centroids from the initial clump detachment, we numerically calculated an initial acceleration to solve for the cohesion that had been restraining the clump. These experimental results show that the detachment of clumps of particles are a non-negligible portion of the lofted object population for cohesive powders. Thus, if electrostatic lofting occurs on small airless bodies, we will likely see clumps lofted.
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    Simulation of Forced Korteweg De Vries Equation as Applied to Small Orbital Debris
    (2020) Truitt, Alexis; Hartzell, Christine
    Sub-centimeter orbital debris is currently undetectable using ground-based radar and optical methods. However, pits in Space Shuttle windows produced by paint chips demonstrate that small debris can cause serious damage to spacecraft. Recent analytical, computational and experimental work has shown that charged objects moving quickly through a plasma will cause the formation of plasma density solitary waves, or solitons. Due to their exposure to the solar wind plasma environment, even the smallest space debris will be charged. Depending on the debris size, charge and velocity, debris may produce plasma solitons that propagate along the debris velocity vector and could be detected with existing sensor technology.
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    Impact of Nanowires on the Properties of Magnetorheological Fluids and Elastomer Composites
    (INTECH, 2010-02) Bell, Richard C.; Zimmerman, Darin T.; Wereley, Norman M.
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    Evaluation of Particle Clustering Algorithms in the Prediction of Brownout Dust Clouds
    (2011-08) Govindarajan, Bharath; Leishman, Gordon
    A study of three Lagrangian particle clustering methods has been conducted with application to the problem of predicting brownout dust clouds that develop when rotorcraft land over surfaces covered with loose sediment. A significant impediment in performing such particle modeling simulations is the extremely large number of particles needed to obtain dust clouds of acceptable fidelity. Computing the motion of each and every individual sediment particle in a dust cloud (which can reach into tens of billions per cubic meter) is computationally prohibitive. The reported work involved the development of computationally efficient clustering algorithms that can be applied to the simulation of dilute gas-particle suspensions at low Reynolds numbers of the relative particle motion. The Gaussian distribution, k-means and Osiptsov's clustering methods were studied in detail to highlight the nuances of each method for a prototypical flow field that mimics the highly unsteady, two-phase vortical particle flow obtained when rotorcraft encounter brownout conditions. It is shown that although clustering algorithms can be problem dependent and have bounds of applicability, they offer the potential to significantly reduce computational costs while retaining the overall accuracy of a brownout dust cloud solution.