Year of Publication

2012

Degree Name

Master of Science in Mechanical Engineering (MSME)

Document Type

Master's Thesis

College

Engineering

Department

Mechanical Engineering

First Advisor

Dr. T. Michael Seigler

Second Advisor

Dr. Sean C. C. Bailey

Abstract

Experiments were conducted to observe the eff ects of an active wire surface on low-Reynolds number Poiseuille flow. The objective was to evaluate the feasibility of actuating piezoelectric nanowires into a travelling wave motion in order to reduce wall shear stress in turbulent flows. Studies have shown that travelling wave motions introduced into the bounding wall of turbulent flow can reduce wall shear stress by disrupting the formation of drag-inducing coherent vortical structures. A Reynolds number scaled flow facility was designed to represent the near-wall region of turbulent flow. A wire surface was installed in the bounding wall and dynamically actuated into a travelling wave. Particle image velocimetry was used to measure the flow. Deviations in the flow were analyzed and a perturbation depth of 5 -- 6 wire lengths was observed. Phase averaged flow fields were examined to evaluate the structure of the disturbances introduced into the flow. Non-dimensional analysis of the results indicated that the modifications to the flow depended on Strouhal number and actuation amplitude, but were independent of Reynolds number. The results suggest that the penetration depth of the flow perturbations introduced by an active nanowire surface is sufficient to influence wall shear stress.

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