Browsing by Subject "Thermal conductivity."
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Item The effect of roughness element thermal conductivity on turbulent convection.(2011-05-12T15:41:42Z) Mart, Steven Robert.; McClain, Stephen Taylor.; Engineering.; Baylor University. Dept. of Mechanical Engineering.Many flows of engineering interest occur over surfaces that exhibit roughness with thermal conductivities much lower than common metals and alloys. This is especially true of in-service gas turbine blades with surface depositions. Depending on the local convection coefficients, low thermal conductivity deposits may create situations where temperature changes along the heights of the elements are important and must be considered in predicting the overall surface convection coefficient. Using four test plates constructed with hexagonal distributions of hemispheres or cones made of either aluminum or ABS plastic, a series of experiments were performed in the Baylor University Subsonic Wind Tunnel to investigate the effects of roughness element thermal conductivities on turbulent convection. Results indicate that the packing density of the elements and the enhancement on the floor of the roughness distribution compete with the roughness element thermal conductivity in determining the overall convection enhancement.Item Non-deterministic modeling of the bulk thermal and electrical conductivity for dense thin film carbon nanotube networks.(2011-05-12T15:14:17Z) Ashtekar, Nikhil A.; Jack, David Abram, 1977-; Engineering.; Baylor University. Dept. of Mechanical Engineering.Thin films composed of single-walled carbon nanotubes, enjoy very high thermal and electrical conductivities, well beyond that of polymer matrix composites, and are very light in weight. Before these materials can experience industrial acceptance the underlying mechanisms dictating their performance must be understood. This research project intends to characterize using a physics based model the bulk thermal and electrical behavior of a neat carbon nanotube network conditions involving stochastic distributions of length, diameter, chirality, orientation obtained from the literature along with theoretical values of the inter-tube distance distribution obtained from in-house studies obtained through MD simulations. The work presents step by step development of the fully three dimensional model for linear, steady state loadings. Case studies using models are presented to better understand the dependence of the bulk thermal and electrical conductivity on the nanoscale parameters, such as bundle length, bundle diameter, orientation, volume fraction. The model is also used to investigate the sensitivity of the thermal and electrical conductivity on select stochastic parameters.