低雷诺数下串列多圆柱流致振动的数值模拟及其机理研究-水利工程专业论文.docxVIP

ABSTRAC Sea currents and tides can provide an abundant of clean and renewable energy. In the past decades, many researchers studied the optimal designs of sea current and tidal energy converters. Globally, the flow velocity of sea currents is generally below 1.5 m/s and conventional tidal energy converters utilizing rotating blades to generate electricity cannot be started. M.M. Bernitsas and K. Raghavan in the University of Michigan invented a novel sea current energy harvesting device——Vortex Induced Vibration Aquatic Clean Energy，VIVACE. The VIVACE converter is based on the idea of extracting energy from the flow-induced vibrations of a circular cylinder or a circular cylinder array and enhancing their amplitude and velocity to improve the energy conversion rate. However, due to the insufficient understanding on the flow-induced vibrations of a cylinder array at present, the theoretic system is far from complete and perfect, which determines the development and application of the VIVACE converter. In this paper, taking the VIVACE converter as the research background, the flow-induced vibrations of three circular cylinders in a tandem arrangement was numerically investigated and reasonable and systematical explanations on the underlying mechanisms of flow-induced vibrations of circular cylinders were presented. The parallel code adopted in this study is CgLes_IBM which has a second order accuracy in both time and space. This code combines the direct numerical simulation of turbulent flow and the iterative immersed boundary method on the purpose of solving the fluid-structure interaction problems. The contents of this paper includes is the flow-induced vibrations of three circular cylinders in a tandem arrangement at a low Reynolds number of Re= 100. Three cylinders can only oscillate freely in the cross-flow direction and the non-dimensional mass of the cylinders is m* =2. The structural damping coefficient is set to zero to obtain the ma