Urban Wind: Impact Of Building Geometry On The Wind Energy Yield Potential Above Rooftops Of Buildings
In increasing the energy available in urban areas, wind energy devices can be placed closer to where they are needed, thus decreasing external electricity demand and transmission costs. This dissertation examines the potential energy yield in the built environment. The primary objective is to show how the potential wind energy at the building rooftop can be increased by modifying and designing the building's structure to accelerate the wind. A crucial element in integrating wind as a source of energy in urban settings is finding ways to maximize wind speed and minimize turbulence intensity. Numerical simulations show that if the building's façade is changed, the flow dynamics at the rooftop can also change significantly leading to an increase in wind speed above the rooftop. To investigate this, a sloped façade building model, an elliptical façade building model, and a modified elliptical (rose façade building) model are compared to a rectangular building model. Both experiments and Computational Fluid Dynamics (CFD) are performed. The numerical simulation code, Fluent, was used to simulate a sloped façade building model at four angles, 20o, 30o, 45o, and 60o for comparison to a rectangular building model. The angle which performed the best, that angle being 30o, was used to experimentally investigate the flow around the sloped façade building and an elliptical façade building with the same angle. CFD is further used to modify the elliptical façade. Parameter correlations are performed to determine an improved building design that increases the available wind energy above the roof compared to the rectangular building model, while catering for the horizontal constraints present in the built environment. To investigate the flow over these modified structures, experiments are performed in an open circuit tunnel where a boundary layer is physically modeled using roughness elements. Results from experimental comparisons of the modified façade structures compared to the rectangular building model show that the rose façade building model, which is designed to minimize the building footprint compared to the sloped and elliptical façade building models, is able to increase the velocity at varying roof locations by as much as 55%. This change in velocity increases the wind power density by over 150%. Thus, changing the building's geometry to influence both the wind and turbulence characteristics above the roof can result in more steady sites for wind harvesting devices leading to increased energy yield.
wind energy; facade
Desjardins,Olivier; Cowen III,Edwin Alfred; Barthelmie,Rebecca Jane
Ph.D. of Mechanical Engineering
Doctor of Philosophy
dissertation or thesis