Vortex induced vibrations: Further contributions and an energy application
Abstract
Vortex shedding and Vortex Induced Vibrations (VIV) of bluff bodies is a
fundamental problem in fluid mechanics. The ubiquity of vortex shedding and VIV in
several engineering fields has meant that a significant amount of research has centered on
this subject. Recent studies have focused on the extraction of energy from steady flow
using bodies undergoing VIV.
In this dissertation, a new model for flow around a circular cylinder called the
Hybrid Potential Flow (HPF) model is presented. The HPF model incorporates potential
flow methods, experimental data and von Karman’s representation of the vortex wake to
construct a complete solution for flow around a circular cylinder in the sub-critical
Reynolds number regime $300 \leq Re \leq 1.5 x 10^5).$ Shedding frequencies and forces due to
vortex shedding are calculated and compared to published results.
The HPF model is extended to other bluff body geometries using conformal
mapping. A composition of Karman-Trefftz transformations and Fornberg’s method is used
to construct a conformal map between the physical domain and the circle plane. The
combination of the HPF model and conformal mapping can thus be used to quickly
calculate vortex shedding behavior for various bluff bodies.
Validation of theoretical results is done through experimental methods. A flow
visualization technique to view the time-averaged wake behind bluff bodies is developed
and presented. Wind tunnel tests are done to validate predicted shedding frequencies for
various bluff body geometries.
A proof-of-concept prototype of a device that extracts energy from steady flow using
VIV is developed. Emphasis is laid on the device being of low cost and complexity. Finally,
principal conclusions of this dissertation and recommendations for future work are
presented.
Description
Thesis (Ph.D.)-- Wichita State University, College of Engineering, Dept. of Aerospace Engineering