Research on wind-wave induced dynamic responses and energy dissipation mechanism of the offshore new floating tube platform with flexible photovoltaic array

The complicated extreme marine environment is a great challenge against development of the offshore new floating photovoltaic (FPV) system. Such structural system is extremely easy to develop large displacement under the wind-wave coupling effect. In particular, it often develops large deformation failures at connectors between floating modules. It is urgent to explore the motion response laws of platform structure and reveal the energy dissipation mechanism between floating modules under wind-wave coupling effect. Based on an offshore floating photovoltaic demonstration base in Dongshan, Fujian Province, China, a new floating tube flexible photovoltaic (FTPV) four-module array model considering flexible connection was proposed. Firstly, the Computational Fluid Dynamics (CFD)/Computational Structural Dynamics (CSD) real-time two-way coupling simulation method based on overlapping grid technology was established. Subsequently, the dynamic response law of FTPV array under three environmental conditions of operation, design and extreme was compared and analyzed, as well as the characteristics of flexible connector load and mooring tension. Finally, the wind-wave induced energy dissipation mechanism between such new floating platform modules was discussed. Research results show that the FTPV array model based on flexible connectors established in this paper can reflect wind-wave induced dynamic response characteristics of such structures accurately. The displacement and rotating angle of the floating tube platform are mainly dominated by longitudinal and vertical displacements as well as pitch angle. The response of the wave-facing platform outside the array is greater than that of the internal region. Under extreme conditions, the pitch angle of the wave-facing side platform is 2.89 times that of the internal region. The load of the flexible connector and the mooring line are characteristic of positive skewing and multi-peak distribution, respectively. The vibration energy of the structure begins to transfer and diffuse with the increase of the environmental load. 70 % of vibration energy resonates in the low-frequency region and the rest 30 % dissipates in the high-frequency region.