This thesis report investigates the effects of low Reynolds number on the power performance of a 3.74 m diameter horizontal axis wind turbine. The small wind turbine was field tested at the Cal Poly Wind Power Research Center to acquire its coefficient of performance, Cp, vs. tip speed ratio, λ, characteristics. A description of both the wind turbine and test setup are provided. Data filtration and processing techniques were developed to ensure a valid method to analyze and characterize wind power measurements taken in a highly variable environment. The test results demonstrated a significant drop in the wind turbine’s power performance as Reynolds number decreased. From Re = 2.76E5 to Re = 1.14E5, the rotor’s Cp_max changed from 0.30 to 0.19. The Cp vs. λ results also displayed a clear change in shape with decreasing Reynolds number. The analysis highlights the influence of the rotor’s Cl /Cd characteristics on the Cp vs. λ curve’s Reynolds number dependency. By not accounting for the effects of varying Reynolds number below the critical value for a rotor operating at constant λ, the design of the rotor planform may overestimate the actual performance of the turbine in real-world conditions. This problem is more evident in distributed-scale wind turbines, compared to utility-scale ones, because of the significantly shorter chord lengths, and therefore increased wind speed range where this effect occurs. Lastly, the wind turbine’s future control method and annual energy production are evaluated using the test results.
","abstract_html":"<p>This thesis report investigates the effects of low Reynolds number on the power performance of a 3.74 m diameter horizontal axis wind turbine. The small wind turbine was field tested at the Cal Poly Wind Power Research Center to acquire its coefficient of performance, <em>C<sub>p</sub></em>, vs. tip speed ratio, <em>λ</em>, characteristics. A description of both the wind turbine and test setup are provided. Data filtration and processing techniques were developed to ensure a valid method to analyze and characterize wind power measurements taken in a highly variable environment. The test results demonstrated a significant drop in the wind turbine’s power performance as Reynolds number decreased. From <em>Re</em> = 2.76E5 to <em>Re </em>= 1.14E5, the rotor’s <em>C<sub>p_max</sub></em> changed from 0.30 to 0.19. The <em>C<sub>p</sub></em> vs.<em> λ</em> results also displayed a clear change in shape with decreasing Reynolds number. The analysis highlights the influence of the rotor’s <em>C<sub>l </sub>/C<sub>d</sub></em> characteristics on the <em>C<sub>p</sub></em> vs.<em> λ</em> curve’s Reynolds number dependency. By not accounting for the effects of varying Reynolds number below the critical value for a rotor operating at constant <em>λ</em>, the design of the rotor planform may overestimate the actual performance of the turbine in real-world conditions. This problem is more evident in distributed-scale wind turbines, compared to utility-scale ones, because of the significantly shorter chord lengths, and therefore increased wind speed range where this effect occurs. Lastly, the wind turbine’s future control method and annual energy production are evaluated using the test results.</p>","abstract_has_math":false,"creators":["Cunningham, John B"],"institution":null,"degree_name":"MS in Mechanical Engineering","degree_level":null,"degree_discipline":"Mechanical Engineering","degree_department":null,"school":null,"contributors":["Patrick Lemieux","Mechanical Engineering","College of Engineering"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2020,"date_issued":"2020-12-01T08:00:00Z","date_published":"2020-12-01T08:00:00Z","updated_at":"2026-07-24T01:32:29Z","subjects":["Wind Energy","Renewable Energy","Aerodynamics","Energy Conversion","Distributed Generation","Distributed Energy","Aerodynamics and Fluid Mechanics","Controls and Control Theory","Energy Systems","Power and Energy"],"languages":[],"rights":[],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier","label":"Identifier","values":["10.15368/theses.2020.152"],"render_values":[{"text":"10.15368/theses.2020.152","href":"https://doi.org/10.15368/theses.2020.152","code":true}]}]},"links":{"outbound_url":"https://digitalcommons.calpoly.edu/theses/2249","outbound_label":"Repository record","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Patrick Lemieux","Mechanical Engineering","College of Engineering"]},{"key":"dc:creator","label":"Author","values":["Cunningham, John B"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.available","label":"Dc Date Available","values":["2020-12-03T08:00:00Z"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Mechanical Engineering"]},{"key":"thesis:degree_name","label":"Degree Name","values":["MS in Mechanical Engineering"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Wind Energy","Renewable Energy","Aerodynamics","Energy Conversion","Distributed Generation","Distributed Energy","Aerodynamics and Fluid Mechanics","Controls and Control Theory","Energy Systems","Power and Energy"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://digitalcommons.calpoly.edu/theses/2249","10.15368/theses.2020.152"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["This thesis report investigates the effects of low Reynolds number on the power performance of a 3.74 m diameter horizontal axis wind turbine. The small wind turbine was field tested at the Cal Poly Wind Power Research Center to acquire its coefficient of performance, Cp, vs. tip speed ratio, λ, characteristics. A description of both the wind turbine and test setup are provided. Data filtration and processing techniques were developed to ensure a valid method to analyze and characterize wind power measurements taken in a highly variable environment. The test results demonstrated a significant drop in the wind turbine’s power performance as Reynolds number decreased. From Re = 2.76E5 to Re = 1.14E5, the rotor’s Cp_max changed from 0.30 to 0.19. The Cp vs. λ results also displayed a clear change in shape with decreasing Reynolds number. The analysis highlights the influence of the rotor’s Cl /Cd characteristics on the Cp vs. λ curve’s Reynolds number dependency. By not accounting for the effects of varying Reynolds number below the critical value for a rotor operating at constant λ, the design of the rotor planform may overestimate the actual performance of the turbine in real-world conditions. This problem is more evident in distributed-scale wind turbines, compared to utility-scale ones, because of the significantly shorter chord lengths, and therefore increased wind speed range where this effect occurs. Lastly, the wind turbine’s future control method and annual energy production are evaluated using the test results.
"]},{"key":"dc:title","label":"Title","values":["Field Testing the Effects of Low Reynolds Number on the Power Performance of the Cal Poly Wind Power Research Center Small Wind Turbine"]}]}],"canonical_facts":{"dc:contributor":["Patrick Lemieux","Mechanical Engineering","College of Engineering"],"dc:creator":["Cunningham, John B"],"dc:date.available":["2020-12-03T08:00:00Z"],"dc:description.abstract":["This thesis report investigates the effects of low Reynolds number on the power performance of a 3.74 m diameter horizontal axis wind turbine. The small wind turbine was field tested at the Cal Poly Wind Power Research Center to acquire its coefficient of performance, Cp, vs. tip speed ratio, λ, characteristics. A description of both the wind turbine and test setup are provided. Data filtration and processing techniques were developed to ensure a valid method to analyze and characterize wind power measurements taken in a highly variable environment. The test results demonstrated a significant drop in the wind turbine’s power performance as Reynolds number decreased. From Re = 2.76E5 to Re = 1.14E5, the rotor’s Cp_max changed from 0.30 to 0.19. The Cp vs. λ results also displayed a clear change in shape with decreasing Reynolds number. The analysis highlights the influence of the rotor’s Cl /Cd characteristics on the Cp vs. λ curve’s Reynolds number dependency. By not accounting for the effects of varying Reynolds number below the critical value for a rotor operating at constant λ, the design of the rotor planform may overestimate the actual performance of the turbine in real-world conditions. This problem is more evident in distributed-scale wind turbines, compared to utility-scale ones, because of the significantly shorter chord lengths, and therefore increased wind speed range where this effect occurs. Lastly, the wind turbine’s future control method and annual energy production are evaluated using the test results.
"],"dc:identifier":["https://digitalcommons.calpoly.edu/theses/2249","10.15368/theses.2020.152"],"dc:subject":["Wind Energy","Renewable Energy","Aerodynamics","Energy Conversion","Distributed Generation","Distributed Energy","Aerodynamics and Fluid Mechanics","Controls and Control Theory","Energy Systems","Power and Energy"],"dc:title":["Field Testing the Effects of Low Reynolds Number on the Power Performance of the Cal Poly Wind Power Research Center Small Wind Turbine"],"thesis:degree_discipline":["Mechanical Engineering"],"thesis:degree_name":["MS in Mechanical Engineering"]},"updated_at":"2026-07-24T01:32:29Z"}