Design And Research On Gravity Based Support Structure Of Tidal Turbine

Tidal current energy is a kind of clean and renewable energy with great potential. Due to the high energy intensity and predictability, utilization of tidal current energy has attracted great attention of the most research groups. The support structures of tidal current generators which are working all over the world have three main fixed forms: gravity-base foundation,pile foundation and floating system. The gravity-base structure form has more mature production technology and can provide stable operation by fixed on the seabed. Therefore, it becomes the most preferred structure form for preliminary design. Support structure is the basis part of the tidal current energy conversion device, which should ensure the turbine operate safely and stably and enable the device against the harsh sea conditions, and also has great significant on the economic benefit. Therefore, the study of support structure has great research value. In this paper, a new kind of support structure has been presented and optimized, and the structure performance has been analyzed by using ANSYS software.The main works in this paper include:(1) Status of tidal current energy development at home and aboard is reviewed, and the support structure forms are summarized. The support structure of a new kind of 2×600kW current turbine is presented.(2) The main scale and basic form of support structure are determined; According to the sea state and DNV-OS-J101 standard, the environmental loads are calculated which include wind load, wave load, current load and ice load. 12 environmental load combinations are obtained. (3) The strength and rigidity of the support structure are analyzed by using ANSYS software. (4) Based on the response surface method,the size of the main components is optimized by use NLPQL (Non-Linear Programming by Quadratic Lagrangian) optimization algorithm. A more reasonable structure design is obtained.After optimization design,the weight of the support structure is reduced by 9%. (5) Consider of the structural stiffening effect, the frequency analysis of support structure is completed, and the natural frequencies and mode shapes are provided. The natural frequency of the support structure has successfully avoided the turbine excitation frequency and the vortex-induced vibration frequency. Therefore, the structure will not resonate. (6) Lateral and axial buckling analysis of the column part of support structure are completed. Based on linear eigenvalue and the double-nonlinear bucklinganalysis, the critical buckling loads are obtained. Since the lateral and axial environmental loads are lower than the critical buckling loads, the local or global buckling will not occur.According to the result, the preliminary design of the support structure is reasonable and can also offer support for further detailed design and similar research.