論文の公開元へ環状流を伴うトーラス構造を有するSPAR-type FOWTの浮体運動特性に関する研究
概要
Under the background of global warming, carbon dioxide peaking and carbon neutrality have become one of the goals that people are striving to achieve. Ocean wind energy has always been one of the renewable energy sources that people value and use from ancient sailing ships to modern ocean wind power generation. However, because of the high center of gravity of floating offshore wind turbines (FOWTs), the hydrodynamic response in the roll and pitch DOFs are relatively large under severe sea conditions. Therefore, if the vast space of the far-reaching sea wind energy is used on a large scale, the problem, of restraining the shaking movement of FOWT, that has always plagued us should be researched and resolved seriously.
Until now, all of FOWTs are moored at sea. In this paper, a novel FOWT without a mooring system is designed, its vacillating motion in severe sea conditions is controlled by a spinning top device that is designed as a neutrally buoyant double-layer torus structure with an annular flow water in the internal small radius torus structure, and is welded to the periphery of the central cylinder of FOWT underwater buoyancy providing part. The torus structure is very common in daily life, such as swimming rings, doughnut desserts, bicycle tires, etc. The torus structure is also often used in scientific research, such as the acceleration track of a particle accelerator in particle physics. The neutral buoyancy can keep the constant draft of FOWT for comparative studies, meanwhile, make that steel rod connecting pieces between the periphery of the central cylinder of FOWT and the external large radius torus structure under vertical force as little as possible, delaying its fatigue. Moreover, the neutral buoyancy will also facilitate installation and removal.
It is envisaged but verified with an experiment in this paper that the principle of the rotating annular flow water in the internal small radius torus structure is the same as the rotation of a rigid body - the spinning top. The fact that the moon revolves around the earth without resistance every lunar month plays a vital role in the stability of the earth's rotation axis. In addition to being used as a stabilizer, the spinning top is also widely used in many fields of engineering. For example, it is used to develop gyrocompass for navigation 100 years ago; the 3-axis gyroscope as the micro-electro-mechanical system is put into Iphone4 published in 2010; furthermore, NASA envisages using it to create gravity in space vehicles, but the rotation radius of the space vehicles is required to exceed 100m…… The gyroscopic effect from the precession of annular flow and the rotational axis retention effect from rotational inertia of annular flow can be obtained for actively restraining the shaking movement of FOWT. If these effects are linearized into the small amplitude problem, they can be treated as a damping force. This paper will study the possibility of contributing to the agitation of FOWT and improving its hydrodynamic response by effectively using these effects.
The presence or absence of the torus structure, the different positions placed in the vertical direction, the radius of the torus structure, the radius of the internal annular flow and the angular velocity of the internal annular flow, the central cylinder radius and the central cylinder height, and the central cylinder wall thickness will be the design variables. Then a large number of comparative calculations based on the fluid-solid coupling theory of potential flow are carried out to determine the appropriate design parameters. Eventually, based on the obtained suitable design parameters, the proposed conceptual design approach is demonstrated to be feasible in view of engineering possibility.
この論文で使われている画像
