Design and Analysis of A Vortex Induced Vibration Based Oscillating Free Stream Energy Converter

The Karman Vortex Shedding is one of the special types of vortex that is generated from asymmetric flow separation. For many years engineers tried to suppress the vortex shedding as it brings unnecessary motion to the static members inside the flow field. A converter model is designed and studied to harness the energy associated with this vortex shedding and convert it into usable form rather than suppressing it. It is a bluff body placed on the free stream incurring vortex-induced vibration and giving out a swinging pendulum motion. This motion is utilized to produce electricity. The model is analyzed on the free stream of water and conversion efficiency of 8.9% is achieved. A theoretical formula is derived regarding the force acting on the bluff body during the motion. Various parameters such as aspect ratio, flow velocity, lock-in delay, frequency of oscillation, etc. as well as their relations are studied by simulating the model in ANSYS FLUENT 18.1 for different configurations. From the simulated results it is obvious that as the lift force on the bluff body increases, more power generation is possible. Also, the experimental results paved the way for further study for practical large-scale implementation of the converter.