Viv of a single cylinder and two cylinders in tandem arrangement: A comparative study of results and energy calculations for maritime renewable energy utilization

Abstract

Renewable energy sources have become increasingly important today, especially when considering the various negative effects and harms caused by other types of energy. When we take the environmental and health impacts of energy sources like coal, gas, and oil into account, it becomes clear that renewable energy should be utilized more extensively in our lives. Some of the negative effects of energy sources other than renewable ones include air pollution, depletion of the ozone layer, reduction of natural greenery, and the proliferation of diseases like cancer among humans. These undesired impacts carry significant risks to both human and environmental health. Therefore, it is essential to understand the necessity of incorporating renewable energy into our lives as a substitute for other energy types. There are many sources available for renewable energy production. Among these, it is essential to highlight solar and water. Renewable energy sources that can be obtained from water include ocean thermal energy, osmotic power, underwater kite systems, tidal energy, and ocean current energy. Vortex-Induced Vibration (VIV) is a phenomenon that can be utilized to harness renewable energy using water as a source. VIV is caused by the formation of the vortices in the fluid flow. When the fluid flow passes the structure, it creates alternating areas of high and low pressure fields around the structure. These pressure differences lead to the generation of vortices, which are swirling regions of fluid motion. In other words, VIV is caused by flow separation from bluff bodies and leads to oscillations. VIV is a subset of Flow-induced motion (FIM). In VIV, the flow exerts a force on the object. The body will move with a frequency in relation to its natural frequency and eddy break frequency. This will lead to a high order nonlinear problem and make it harder to solve. Flow separations occur when a structure is not aligned with the hydrodynamics of the flow. Eddies are formed when the flow leaves the object and eventually creates force on it. When VIV occurs on a body in water, it is possible to implement a system that can convert the hydrokinetic energy in the water into mechanical energy. Useful energy extraction from flowing water is one of the hot topics of the academic literature today. Among the many devices that are developed towards this goal, VIVACE (Vortex Induced Vibration for Aquatic Clean Energy) stands out. It is a converter that converts the ocean/river current energy to electricity. A VIVACE has the aim of maximizing VIV and converting its mechanical energy extracted from the moving fluid flow into electrical power. From the structural perspective, VIV is an unwanted phenomenon as it disturbs and causes damage to a structure. However, it can also prove beneficial by harnessing energy through the utilization of an oscillator system, converting the mechanical energy obtained from these oscillations into electricity, all without impeding its Flow Induced Oscillations (FIO). VIV can be excited in a wide range of Reynolds numbers. This means that by having a Reynolds number of Re>50, this system can be utilized for energy and power generation across a broad range of flow regimes. Although lab-scale prototypes of VIVACE systems can generally reach the maximum Reynolds number of 1.35×〖10〗^5, full-scale VIVACE systems have the potential to reach 〖10〗^7, proving the scalability of the device. VIV can also be identified as a synchronization between vortex shedding and cylinder oscillations. The main aim of VIVACE converter is to enhance the vortex shedding rather than spoiling and maximize under significant damping rather than suppressing VIV's. This converter can extract energy from currents of velocities 0.5