Pressure Drag Reduction on Patterned Cylindrical Models Inspired by Biomimicry

• Other Authors: Ferreira, Larissa Mendes (authoraut)
• Format: Others
• Language: English; English
• Published: Florida State University
• Subjects: Civil engineering; Aerospace engineering
• Online Access: http://purl.flvc.org/fsu/fd/FSU_migr_etd-9332

Extensive research has been previously conducted on cylindrical models with different surface patterns. These experiments were generally performed with the intention of passively reducing friction drag on aerodynamic structures exposed to laminar flows. Incorporating knowledge from this, the present research aims to quantify the effectiveness of similar surface patterns in reducing pressure (form) drag for structures exposed to turbulent flow through wind tunnel experiments. The surface patterns selected are originally inspired from marine animal anatomy. V-grooved riblets mimic the miniscule patterns found on a sharks' skin, which aid sharks in reducing drag while propelling forward in the water. U-grooved riblets (ie: bumps) mimic the tubercles located on the leading edge of a humpback whale's pectoral fins, which serve to increase maximum lift and reduce drag. In addition to patterned cylinders, pressure tests will also be conducted on a smooth-surfaced cylinder, serving as the control of the experiment. Since the length of the wind tunnel test section is short in comparison to the length of wind tunnels regularly used for this type of testing, having a 0.61m x 0.61m x 2m test section, there needs to be an array of roughness elements placed at the upstream end of the test section. These elements will serve to induce a thicker atmospheric boundary layer (ABL) within the test section before interacting with the test specimen. After a series of experimental tests, this project successfully generated an ABL in a short tunnel which allowed for a detailed study of the effects of surface patterns on scaled-down versions of high-rise structures. The results indicated that the cylinder covered in V-grooved riblets was most effective in reducing pressure drag when subjected to a turbulent flow characteristics. === A Thesis submitted to the Department of Civil and Environmental Engineering in partial fulfillment of the requirements for the degree of Master of Science. === Spring Semester, 2015. === April 17, 2015. === Atmospheric boundary layer, Cylindrical model, Pressure drag, Riblet, Short wind tunnel, Surface pattern === Includes bibliographical references. === Sungmoon Jung, Professor Directing Thesis; Michelle Rambo-Roddenberry, Committee Member; Lisa Spainhour, Committee Member.