Vortex-induced vibrations of flexible, buoyant, three-dimensional bluff bodies for energy conversion-storage applications

Abstract

While the engineering community is making leaps and bounds in the renewable energy area, several issues remain. Some of the most prevalent issues are intermittency and low efficiencies. To overcome these challenges, one of the solutions used is implementing integrated storage.   Several different types of integrated storage technologies have been proposed. These technologies were thoroughly reviewed, and their performance was compared against each other as the first phase of this research. Then, the Storage-integrAted Vortex hydro Energy converteR (SAVER) was introduced.  At the heart of SAVER, flexible, buoyant, finite cylinders, namely accumulator-converters, serve as both energy accumulator and energy converter modules. These cylinders store energy in the form of potential energy of compressed air while extracting kinetic energy of underwater currents via vortex-induced vibrations. These linear vibrations drive a generator through a crank-shaft mechanism. The unit will utilize the generated energy to overcome the losses that occur during the energy conversion processes. SAVER has been mathematically shown to have a round-trip efficiency upwards of at least 80%. To develop the most effective design for this technology, one needs to have a deep understanding of vortex-induced vibrations of the accumulator-converters, which are flexible, deformable, buoyant, finite (introducing the end effects), and affected by turbulence boundary layers. This very complex and fundamental fluid-structure problem has not been studied yet and the literature is mainly focused on vortex-induced vibrations of rigid bluff bodies. The main purpose of this research is addressing this gap using numerical simulations in concert with laboratory experiments.