This project examined the effect of Gurney flaps on a 2D, 2-ft chord NACA 0036 airfoil in the Cal Poly 3’x4’ low speed wind tunnel at 25 m/s. It also covered the numerical simulation of the experiment in computational fluid dynamics (CFD). During the study, problems with the wind tunnel data were seen. After a careful diagnosis, the problem was traced to dirty flow conditioners which were subsequently replaced.
Five Gurney flaps at 1, 2, 3, 4, and 5% of the chord were tested. The Gurney flaps had the effect of eliminating the lift reversal effect and lowering the profile drag at low angles of attack, ranging from 4-27%. The optimal Gurney flap appeared to be 2% of the chord. CFD modeling of the problem had limited success, with the best results coming from Mentor’s k-w SST turbulence model. This model reproduced the non-linear lift curve, and captured the trend in rising drag fairly well, but failed to predict the correct point of separation. Attempts to model the Gurney flap in CFD were unsuccessful.
","abstract_html":"<p>This project examined the effect of Gurney flaps on a 2D, 2-ft chord NACA 0036 airfoil in the Cal Poly 3’x4’ low speed wind tunnel at 25 m/s. It also covered the numerical simulation of the experiment in computational fluid dynamics (CFD). During the study, problems with the wind tunnel data were seen. After a careful diagnosis, the problem was traced to dirty flow conditioners which were subsequently replaced. </p> <p>Five Gurney flaps at 1, 2, 3, 4, and 5% of the chord were tested. The Gurney flaps had the effect of eliminating the lift reversal effect and lowering the profile drag at low angles of attack, ranging from 4-27%. The optimal Gurney flap appeared to be 2% of the chord. CFD modeling of the problem had limited success, with the best results coming from Mentor’s k-w SST turbulence model. This model reproduced the non-linear lift curve, and captured the trend in rising drag fairly well, but failed to predict the correct point of separation. Attempts to model the Gurney flap in CFD were unsuccessful.</p>","abstract_has_math":false,"creators":["Altmann, Gregory F"],"institution":null,"degree_name":"MS in Aerospace Engineering","degree_level":null,"degree_discipline":"Aerospace Engineering","degree_department":null,"school":null,"contributors":["Jin Tso"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2011,"date_issued":"2011-03-01T08:00:00Z","date_published":"2011-03-01T08:00:00Z","updated_at":"2026-07-24T01:31:11Z","subjects":["Wind Tunnel","Gurney flap","NACA 0036","Aerodynamics and Fluid Mechanics"],"languages":[],"rights":[],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier","label":"Identifier","values":["10.15368/theses.2011.44"],"render_values":[{"text":"10.15368/theses.2011.44","href":"https://doi.org/10.15368/theses.2011.44","code":true}]}]},"links":{"outbound_url":"https://digitalcommons.calpoly.edu/theses/524","outbound_label":"Repository record","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Jin Tso"]},{"key":"dc:creator","label":"Author","values":["Altmann, Gregory F"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.available","label":"Dc Date Available","values":["2011-06-08T07:00:00Z"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Aerospace Engineering"]},{"key":"thesis:degree_name","label":"Degree Name","values":["MS in Aerospace Engineering"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Wind Tunnel","Gurney flap","NACA 0036","Aerodynamics and Fluid Mechanics"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://digitalcommons.calpoly.edu/theses/524","10.15368/theses.2011.44"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["This project examined the effect of Gurney flaps on a 2D, 2-ft chord NACA 0036 airfoil in the Cal Poly 3’x4’ low speed wind tunnel at 25 m/s. It also covered the numerical simulation of the experiment in computational fluid dynamics (CFD). During the study, problems with the wind tunnel data were seen. After a careful diagnosis, the problem was traced to dirty flow conditioners which were subsequently replaced.
Five Gurney flaps at 1, 2, 3, 4, and 5% of the chord were tested. The Gurney flaps had the effect of eliminating the lift reversal effect and lowering the profile drag at low angles of attack, ranging from 4-27%. The optimal Gurney flap appeared to be 2% of the chord. CFD modeling of the problem had limited success, with the best results coming from Mentor’s k-w SST turbulence model. This model reproduced the non-linear lift curve, and captured the trend in rising drag fairly well, but failed to predict the correct point of separation. Attempts to model the Gurney flap in CFD were unsuccessful.
"]},{"key":"dc:title","label":"Title","values":["An Investigative Study of Gurney Flaps on a NACA 0036 Airfoil"]}]}],"canonical_facts":{"dc:contributor":["Jin Tso"],"dc:creator":["Altmann, Gregory F"],"dc:date.available":["2011-06-08T07:00:00Z"],"dc:description.abstract":["This project examined the effect of Gurney flaps on a 2D, 2-ft chord NACA 0036 airfoil in the Cal Poly 3’x4’ low speed wind tunnel at 25 m/s. It also covered the numerical simulation of the experiment in computational fluid dynamics (CFD). During the study, problems with the wind tunnel data were seen. After a careful diagnosis, the problem was traced to dirty flow conditioners which were subsequently replaced.
Five Gurney flaps at 1, 2, 3, 4, and 5% of the chord were tested. The Gurney flaps had the effect of eliminating the lift reversal effect and lowering the profile drag at low angles of attack, ranging from 4-27%. The optimal Gurney flap appeared to be 2% of the chord. CFD modeling of the problem had limited success, with the best results coming from Mentor’s k-w SST turbulence model. This model reproduced the non-linear lift curve, and captured the trend in rising drag fairly well, but failed to predict the correct point of separation. Attempts to model the Gurney flap in CFD were unsuccessful.
"],"dc:identifier":["https://digitalcommons.calpoly.edu/theses/524","10.15368/theses.2011.44"],"dc:subject":["Wind Tunnel","Gurney flap","NACA 0036","Aerodynamics and Fluid Mechanics"],"dc:title":["An Investigative Study of Gurney Flaps on a NACA 0036 Airfoil"],"thesis:degree_discipline":["Aerospace Engineering"],"thesis:degree_name":["MS in Aerospace Engineering"]},"updated_at":"2026-07-24T01:31:11Z"}