Portland State University. Department of Mechanical and Materials Engineering
Raúl Bayoán Cal
Term of Graduation
Date of Publication
Doctor of Philosophy (Ph.D.) in Mechanical Engineering
Mechanical and Materials Engineering
Turbulence, Forest canopies, Wind power plants -- Design and construction, Wakes (Aerodynamics), Wind power
1 online resource (xx, 179 pages)
Large canopies interact with the atmospheric boundary layer (ABL) and alter transport of matter, energy, and momentum in accordance to their morphology. Canopy structure influence on turbulent processes can be utilized to achieve favorable interactions. Wind farm and forest canopies spatial arrangement is investigated in this work. Momentum fluxes investigated in a horizontal axis wind turbine (HAWT) array showed the existence of gusts of wind transported both from ABL above the canopy and the unperturbed flow below the canopy through sweep and ejection events. A new wind farm arrangement in which clusters of vertical axis wind turbines (VAWT) are collocated with HAWTs is proposed to enhance power harvested per unit area. An aligned collocated arrangement is found to increase power production by 3.5%. This approach opens possibilities to further optimize the collocation layout and determine the arrangement that extracts most power. Other considerations in terms of renewable energy production are focused on advancing offshore wind farms design by considering their wake flow intermittency due to its consequence in increasing dynamic loading on the turbine structure. It is found that pitch motion increases intermittency in floating wind turbine wake up to five turbine diameters downstream the turbine and shorter in highly turbulent flow. Furthermore, a heterogeneity parameter is developed to measure spatial variations in canopies. The parameter proved successful in measuring heterogeneity of forest canopies with various spatial arrangements. Momentum advection was found to increase up to 14 times that of a homogeneous canopy. Power law relation is determined between heterogeneity parameter and momentum advection. These findings have implications in determining environmentally viable forest management and enhanced weather forecasting. Understanding the dynamics between turbulent processes and spatial variations in canopies is of essence to exploit them in sustainable development.
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Kadum, Hawwa Falih, "Mechanics of Canopy Turbulence" (2020). Dissertations and Theses. Paper 5518.