Date of Award
Spring 2023
Embargo Period
5-1-2025
Access Type
Thesis - Open Access
Degree Name
Master of Aerospace Engineering
Department
Aerospace Engineering
Committee Chair
Dr. Ebenezer Gnanamanickam
First Committee Member
Dr. Anastasios Lyrintzis
Second Committee Member
Dr. Richard Prazenica
College Dean
Dr. James W. Gregory
Abstract
Bio-inspired wing tip devices were investigated with the goal of improving the fuel efficiency of subsonic aircraft. Particularly, the structure of a bio-inspired winglet design based on bird feathers were tested in a low-speed wind tunnel. Particle image velocimetry (PIV), was used to study the flow field at two planes aft of the wing as the wing tip vortices developed downstream. These were time-dependent, stereoscopic particle image velocimetry (sPIV) measurements carried out at two planes located at 0.7 and 2 chord distances downstream from the wing. The structure of the wingtip vortices was compared and contrasted with that formed over a wing without a wing tip device and that over a conventional winglet such as that seen in general aviation. In addition, the aerodynamic characteristics obtained using force balance measurements (as part of a previous study) were analyzed to determine an approximation for the induced drag. The wing with the bio-inspired winglet generated the highest lift at a given angle of attack, as reported previously. At higher angles of attack, the wing with the conventional winglet had the minimum induced drag. All three wing configurations generated significant vortical motion at the wing tip. The wing with no attachment and the wing with the conventional winglet showed the distinct signature of a vortex. The mean velocity, mean vorticity and turbulence intensity fields collectively presented strong evidence that the wing without an attachment had a larger vortex core at both downstream locations considered, when compared to the wing with the conventional winglet. However, in contrast, the wing with the bio-inspired wing tip device showed no clear vortex core at both downstream locations. Instead, pockets of vorticity were observed. These pockets appeared to organize itself into a larger vortex at the downstream location. In addition, the wing with the bio-inspired winglet also appeared to have a larger more diffused vortical structure when compared to the other configurations.
Scholarly Commons Citation
Daniel, Greeshma C., "Understanding the structure of wing tip vortices of bio-inspired winglets" (2023). Doctoral Dissertations and Master's Theses. 747.
https://commons.erau.edu/edt/747
