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Full-Text Articles in Engineering
Permeability, Structural Changes, Flow Regime Transitions In Fuel Cell Catalyst Layers And A Model For Predicting Trapped Saturation For Two-Phase Flow In Porous Media, Karrar Takleef Alofari
Permeability, Structural Changes, Flow Regime Transitions In Fuel Cell Catalyst Layers And A Model For Predicting Trapped Saturation For Two-Phase Flow In Porous Media, Karrar Takleef Alofari
Dissertations, Master's Theses and Master's Reports
Proper water management in Proton Exchange Membrane (PEM) fuel cell is important to achieve high performance. Understanding the percolation of the produced water at the cathode catalyst layer (CL) is critical for any robust water management technique. In this study, an ex-situ experimental setup is used to study percolation in the CL at different injection rates and relative humidity (RH) conditions. The results show that increasing the flow rate force the liquid to flow through the bulk of the pores due to the dominant viscous effect. On the other hand, at low injection rates, the capillary becomes dominant and liquid …
Microscale Transverse Compression Modeling: A Comparative Study Of The Analytical Mac/Gmc Methods To Experimental Results, Emily Zeitunian
Microscale Transverse Compression Modeling: A Comparative Study Of The Analytical Mac/Gmc Methods To Experimental Results, Emily Zeitunian
Dissertations, Master's Theses and Master's Reports
Composite materials require a multi-scale approach to fully understand its behavior. At the micro level, material behavior analysis is conducted most often using numerical or analytical approaches. These models, however, require validation from experimental data to ensure material predictions are accurate. This study compares a semi-analytical micromechanical analysis tool, MAC/GMC, to experimental results of in-situ microscale transverse compression testing conducted at AFRL facilities. Effective properties, stress-strain curves, stress and strain fields, and damage predictions are compared with experimental outputs. Both generalized method of cells (GMC) and high-fidelity generalized method of cells (HFGMC) theories implemented within MAC/GMC show results that agree …
Design And Analysis Of Marangoni-Driven Robotic Surfers, Mitchel L. Timm
Design And Analysis Of Marangoni-Driven Robotic Surfers, Mitchel L. Timm
Dissertations, Master's Theses and Master's Reports
We designed and experimentally studied the dynamics of two robotic systems that surf along the water-air interface. The robots were self-propelled by means of creating and maintaining a surface tension gradient resulting from an asymmetric release of isopropyl alcohol (IPA). The imbalance in the distribution of surface tension surrounding the robots generates a propulsive force commonly referred to as Marangoni propulsion. First, we considered a single surfer, which was custom-made with novel control mechanisms that allow for both forward motion and steering to be remotely adjusted solely through the manipulation of local surface stresses. We analyzed the performance of this …