Date of Award
Spring 5-10-2025
Level of Access Assigned by Author
Open-Access Thesis
Degree Name
Master of Science (MS)
Department
Mechanical Engineering
First Committee Advisor
Richard Kimball
Second Committee Member
Andrew Goupee
Third Committee Member
Amrit Verma
Abstract
This research focuses on evaluating the W2 wind tunnel and the wind environment it produces. The initial phase involved thoroughly characterizing the wind, quantifying the turbulence characteristics, maximum attainable wind speed, and flow uniformity across the test area, to fill gaps in the understanding of these characteristics which remain from prior measurements. The methodology for this characterization, particularly the use of hot-wire anemometers, was documented, providing a standardized procedure for the lab to use in the future.
The data collected during this characterization was processed, and the performance of the wind generator was compared to published results for similar facilities. Several areas for improvement were identified, primarily the uniformity resulting from flow around the fans and the influence of the upper and lower boundary layers. Additionally, the efficiency of the wind tunnel was found to be fairly poor, limiting the maximum attainable wind speed and forcing the tunnel to operate at higher (and louder) fan RPMs.
A flow straightening stator and a non-uniform screen insert were conceptualized, which would sit downstream of the fans to improve efficiency and uniformity. A CFD model of the wind tunnel was developed and tuned to match the performance and flow geometries measured experimentally. The stator and screen insert designs were evaluated and improved upon using the CFD model, and then prototypes of each were fabricated and tested experimentally to validate these findings. The shape coefficient of variation (CoV) and energy ratio were parameters defined to quantify spatial variation of velocity and efficiency of the wind tunnel. These were predicted to improve from 5.6% to 0.4% and from 6.5% to 7.1%
respectively with the Stator and Screen Insert Installed. When measured experimentally, the Shape CoV improved from 5.55% to 1.05%, with no detectable change in the energy ratio.
Although the effectiveness of the design modifications was somewhat overstated by the CFD predictions, these results showed that the uniformity could be improved significantly without sacrificing efficiency. They also showed that the CFD model created here could be a useful design tool for developing design modifications and predicting their efficacy.
Recommended Citation
Bourque, Casey, "Characterization and Improvement of the Wind Environment for Scale Model Floating Offshore Wind Turbines in the University of Maine’s Wind Wave Basin" (2025). Electronic Theses and Dissertations. 4166.
https://digitalcommons.library.umaine.edu/etd/4166
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Comments
This research focuses on evaluating the W2 wind tunnel and the wind environment it produces. The initial phase involved thoroughly characterizing the wind, quantifying the turbulence characteristics, maximum attainable wind speed, and flow uniformity across the test area, to fill gaps in the understanding of these characteristics which remain from prior measurements. The methodology for this characterization, particularly the use of hot-wire anemometers, was documented, providing a standardized procedure for the lab to use in the future.
The data collected during this characterization was processed, and the performance of the wind generator was compared to published results for similar facilities. Several areas for improvement were identified, primarily the uniformity resulting from flow around the fans and the influence of the upper and lower boundary layers. Additionally, the efficiency of the wind tunnel was found to be fairly poor, limiting the maximum attainable wind speed and forcing the tunnel to operate at higher (and louder) fan RPMs.
A flow straightening stator and a non-uniform screen insert were conceptualized, which would sit downstream of the fans to improve efficiency and uniformity. A CFD model of the wind tunnel was developed and tuned to match the performance and flow geometries measured experimentally. The stator and screen insert designs were evaluated and improved upon using the CFD model, and then prototypes of each were fabricated and tested experimentally to validate these findings. The shape coefficient of variation (CoV) and energy ratio were parameters defined to quantify spatial variation of velocity and efficiency of the wind tunnel. These were predicted to improve from 5.6% to 0.4% and from 6.5% to 7.1%
respectively with the Stator and Screen Insert Installed. When measured experimentally, the Shape CoV improved from 5.55% to 1.05%, with no detectable change in the energy ratio.
Although the effectiveness of the design modifications was somewhat overstated by the CFD predictions, these results showed that the uniformity could be improved significantly without sacrificing efficiency. They also showed that the CFD model created here could be a useful design tool for developing design modifications and predicting their efficacy.