Engineering Commons^™

Experimental Investigation Of The Phase Change Process Within Circular Geometries, Kyle Teather

Electronic Thesis and Dissertation Repository

Latent heat thermal energy storage systems have many advantages over sensible-heat-based thermal storage systems, such as an increased energy density with a narrower range of operating temperatures. The main barrier to implementing latent heat storage systems is the low thermal conductivity of typical storage materials, called phase change materials (PCMs). Furthermore, the heat transfer mode in the liquid phase is natural convection, which is influenced by the geometry and orientation of the heat source and sink, thus impacting the phase change pattern and heat transfer. It is critical to have a good understanding of the underlying fundamental physics over the …

Experimental Simulation Of A Density-Driven Downburst Translating Within A Turbulent Boundary Layer, Shivani Ashitkumar Jariwala

Electronic Thesis and Dissertation Repository

Downburst outflows emerging from thunderstorm producing clouds are contained within the atmosphere where the outflow interacts with the preexisting atmospheric boundary layer (ABL). This novel study employs a realistic approach for experimental simulation of downbursts by translating the downburst source within a scaled ABL within a hydraulic flume system that produces open channel flow. The density-driven model approach is used, involving an iris operated cylinder release mechanism translating inside the ABL generated over a restrictive fetch using passive turbulence generating devices at model scales of 1:5500 and 1:10,000. The velocity vector fields across a vertical plane revealed asymmetrical outflows generated …

Investigation Of Flow And Thermal Behaviour In A Pipe Submerged In A Hot Fluid, Ben S. Steen

Electronic Thesis and Dissertation Repository

Convection heat transfer through a pipe immersed in a stagnant fluid is used in various applications such as water heaters, chemical and food industry, etc. In this study, the effect of mixed convection on the flow and thermal structure of a fluid immersed inside a hotter, stagnant fluid was experimentally investigated. Temperature and velocity fields were obtained for a Reynolds number range of 330-6670, and a Grashof number range of 14000-95000 (0.6 < Gr/Re² < 0.0003). It was found that the buoyancy-induced wall-normal velocity component altered the streamwise velocity structure and the temperature profiles. The mean streamwise velocity profile was skewed towards the bottom of the pipe for initially laminar flow only. A vertical temperature gradient was also observed in the internal fluid under these conditions, where the hotter fluid resided in the top region of the pipe. The Nusselt number was found to moderately follow the predictive Gnielinski correlation, with an additional dependence on the bottom wall temperature. This showed that an increase in the Grashof number tended to dampen the turbulent convective heat transfer. The influence of natural convection on the mean and turbulent velocity profiles was found to be almost negligible in the high Reynolds number range.

Vortex Shedding From Elongated Bluff Bodies, Zachary J. Taylor

Electronic Thesis and Dissertation Repository

As the spans of suspension bridges increase, the structures become inherently flexible. The flexibility of these structures, combined with the wind and particular aerodynamics, can lead to significant motions. From the collapse due to flutter of the Tacoma Narrows Bridge to the case of vortex-induced vibrations (VIV) of the Storebælt Bridge, it is evident that a better understanding of the aerodynamics of these geometries is necessary. The work herein is motivated by these two problems and is presented in two parts.

In the first part, the focus is on the physical mechanisms of vortex shedding. It is shown that the …