Wind turbine arrays operate under highly variable natural conditions such as high turbulence variability, surface terrain and temperature gradients. In particular, thermal stratification of the atmosphere produces vertical exchanges of heat flux, which have direct impact on the kinetic energy of the flow. The influence of wind turbine (WT) arrays on these exchanges and the stratified atmosphere is not known. Insight on such interactions can prolong the life of the WTs, maximize power extraction out of the WT arrays, and help understand the impact of such arrays on the atmosphere.
The proposed research focuses on an experimental study of flow, fluxes and energetics of wind turbine arrays in a wind tunnel. The goal of this study is to quantify and understand the atmospheric exchanges and power extraction on a stratified atmospheric turbulent boundary layer (ATBL) coupled with a wind turbine array. Currently, stratification is studied to understand pollutant dispersion, whereas wind turbine studies focus mainly on the aerodynamic of blades and wakes shed from a single WT. The proposed research will examine the behavior of wind turbine arrays under thermal stratification. These experimental studies will be carried at the state-of-the-art wind tunnel facility housed in the Green Building Research Laboratory at Portland State University (PSU).
Tomographic particle image velocimetry and cold-wire anemometry will be used to measure high-resolution velocity and temperature maps, respectively, in the experimental WT array. Results will be condensed into useful parameterizations and models that may be used in micro, meso, and global simulations of wind-turbine arrays in a stably and unstably stratified atmosphere. The proposed research seeks to advance understanding of wind energy extraction from the atmospheric environment under thermal stratification to ultimately facilitate the design of WT arrays under realistic conditions.
Broader Impacts
The education plan emphasizes cross-cultural and international research experiences for both undergraduate and graduate students. Three undergraduate students will be recruited from Turabo University (Puerto Rico) and PSU to participate in a research-intensive summer program. These students will gain exposure to engineering aspects of wind energy by working with state-of-the-art facilities for wind tunnel testing and flow visualization. Graduate students will travel to Norway to during the summer to collaborate with researchers at Norwegian Defense Research Establishment (FFI) on the modeling aspects of the research.
The outreach plan emphasizes exposure of high-school students to STEM topics. The wind tunnel facility has the capability to carry out experiments remotely using a web-based platform. Remote wind tunnel experiments will be carried out in a high school classroom in partnership with Gladstone High School to expose students to STEM and sustainability topics. Through school-based programs, Oregon MESA (Mathematics Engineering Science Achievement) strives to increase the number of minority and women engineers in Oregon. The PI and graduate students will participate in MESA Day through hands-on experiments in fluid mechanics with students recruited through the MESA program, complemented by tours to the PSU wind tunnel facility.
