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Technical Paper

Effects of Condenser Two-Phase Flow Characteristics on a Capillary Pumped Loop

2000-07-10
2000-01-2321
One of the intrinsic characteristics found in CPL operation is the oscillatory behavior of the pressure drop, even noted under seemingly steady operation. This study focused on the role of the condensing process and its intrinsic instabilities upon the differential pressure oscillations recorded in the CPL. Through an analytical study of condensing instabilities and an experimental study based on the correlation between pressure records and condensing flow visualization, the impact of slug flow phenomenon occurring in the condensing path was investigated. High amplitude oscillations were seen to be linked with liquid slug phenomena in the way that slug striking the final vapor-liquid interface generated pressure pulses.
Technical Paper

Exploration of Support Methods for Tradespace Exploration

2023-04-11
2023-01-0117
Tradespace exploration (TSE) is an important aspect of the early stages of the design process, in which stakeholders search for the most optimal solutions within a design variable-bounded solution space. This decision-making process requires stakeholders to understand the trade-offs and compromises that may be required to choose a solution. In order for stakeholders to make these decisions appropriately, information must be presented in an efficient manner and should ensure that the trade-offs between solutions are clearly visible. Existing visualizations often struggle to elucidate these trade-offs, and can rapidly become difficult to understand as the dimensionality of the tradespace increases. In this paper, the benefits and drawbacks to these existing methods will be discussed. In addition, this paper will explore potential methods to improve information presentation for TSE, including framing, visual steering, and visualization options.
Technical Paper

Wear Resistance of Lunar Wheel Treads Made of Polymeric Fabrics

2009-04-20
2009-01-0065
The purpose of this research is to characterize the wear resistance of wheel treads made of polymeric woven and non-woven fabrics. Experimental research is used to characterize two wear mechanisms: (1) external wear due to large sliding between the tread and rocks, and (2) external wear due to small sliding between the tread and abrasive sand. Experimental setups include an abrasion tester and a small-scale merry-go-round where the tread is attached to a deformable rolling wheel. The wear resistance is characterized using various measures including, quantitatively, by the number of cycles to failure, and qualitatively, by micro-visual inspection of the fibers’ surface. This paper describes the issues related to each experiment and discusses the results obtained with different polymeric materials, fabric densities and sizes. The predominant wear mechanism is identified and should then be used as one of the criteria for further design of the tread.
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