Duke University
Pratt School of Engineering
Durham NC, 27705
Flag Flutter
The stability of an elastic plate in axial incompressible subsonic flow has been studied by several scholars, beginning in 1968 with experimental observations of a flapping flag by Taneda. Flutter is a specifc dynamic instability of a structure in a moving fluid that exhibits unsteady and large oscillations due to the interaction between the structure and the fluid. Historically, the majority of utter research has been focused on suppressing flutter because it is catastrophic in many structures including aircraft, bridges, and turbomachinery. Recently, attention has been refocused to gain a better understanding of flutter due to a growing interest in small scale energy harvesting systems. Even though attention has been refocused there remain signifcant diferences between existing theoretical predictions and experimental observations.
I have created a theory and code that models the three dimensional aerodynamic forces acting on a structure which is modeled with energy methods using modal coordinates. I determine the modal coordinates either analytically or, for more complicated geometries, using finite element methods. I model the aerodynamics using a Vortex Lattice Model (VLM) which captures the forces created by a three-dimensional, incompressible flow by tracking the motion and the strengths of a set of horseshoe vorcitices which are solutions to the governing potential flow equation. I then solve the coupled aeroelastic equations in the frequency domain and track how the modal damping and frequency for a desired configuration change with the wind conditions. Unlike previous researchers, I have non-dimensionalized my equations to allow an exploration of a systems behavior as its fundamental non-dimensional parameters change.
- Gibbs,S.C "Theory and Experiment for Flutter of a Rectangular Plate with a Fixed Leading Edge in Three-Dimensional Axial Flow", Department Retreat Presentation, October 2011
- Gibbs,S.C "Flutter Prediction with Experiments for Vary Boundary Condition Low Aspect Ratio Flapping Wings", Lab Group Presentation, June 2011
Modern Steam Engine
Question: Could a modern steam engine that is made with modern materials and electronic valves be a viable solution to the internal combustion engine?
Motivation: Steam engines create power from steam in a cycle that is more efficient than the internal combustion cycle and produces more low end torque than a comparable size IC engine . Steam can be generated from a wide variety of renewable sources including biomass as well as solar. These provided the incentive to explore whether a steam engine could be viable in the 21st Century
The group is currently working to finalize a design for the steam piston and set-up. Included are presentations, links to videos and documentation for the project. It is hoped that the setup will be used by researchers in the future at Duke
- Gibbs, S. C., "Electronic Engine Control and Optimization", Departmental Distinction Paper, May 2010
- Gibbs, S. C., "Electronic Engine Control and Optimization", Departmental Distinction Presentation, May 2010
- Test Rig User Manual
- Valve Flow Rate Test
Hydrokinetic Turbine
To Be Added