Iced Airfoil Separation Bubble Measurements by Particle Image Velocimetry

Previous iced airfoil investigations have demonstrated somewhat reduced aerodynamic penalties resulting from a three-dimensional ice simulation, compared to those of a two-dimensional ice simulation of a representative cross section. Correspondingly, the current measurements revealed accelerated transition of the separated shear layer emanating from a three-dimensional ice simulation and therefore enhanced pressure recovery and reduced mean separation bubble length, each relative to the flowfield of a representative two-dimensional ice simulation. These effects appeared to result from the quasi-steady distribution of discrete, streamwise vortices which aided the turbulent entrainment of fluid from the recirculation region of the three-dimensional ice simulation separation bubble flowfield. These vortices were generated by a streamwise-vortex instability excited by roughness along the three-dimensional ice simulation and produced spanwise-cell structures throughout this flowfield, as well as significant spanwise variation in peak turbulence statistics. However, these variations were strongly correlated to the local degree of flowfield three-dimensionality observed from surface oil-flow visualization, indicating a three-dimensional relieving effect, such that measurements within a quasi-two-dimensional spanwise region were both qualitatively and quantitatively similar to those of the two-dimensional ice simulation separation bubble flowfield.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Aerospace Engineering

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2015

Author dc:creator

• Jacobs, Jason J.

Contributors dc:contributor

• Bragg, Michael B.

• Engineering, Aerospace

Language dc:language

eng

Identifier

(MiAaPQ)AAI3290256

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/85103