Dynamic Loads and Response of a Spar Buoy Wind Turbine with Pitch-Controlled Rotating Blades: An Experimental Study

Abstract

New large-scale laboratory data are presented on a physical model of a spar buoy wind turbine with angular motion of control surfaces implemented (pitch control). The peculiarity of this type of rotating blade represents an essential aspect when studying floating offshore wind structures. Experiments were designed specifically to compare different operational environmental conditions in terms of wave steepness and wind speed. Results discussed here were derived from an analysis of only a part of the whole dataset. Consistent with recent small-scale experiments, data clearly show that the waves contributed to most of the model motions and mooring loads. A significant nonlinear behavior for sway, roll and yaw has been detected, whereas an increase in the wave period makes the wind speed less influential for surge, heave and pitch. In general, as the steepness increases, the oscillations decrease. However, higher wind speed does not mean greater platform motions. Data also indicate a significant role of the blade rotation in the turbine thrust, nacelle dynamic forces and power in six degrees of freedom. Certain pairs of wind speed-wave steepness are particularly unfavorable, since the first harmonic of the rotor (coupled to the first wave harmonic) causes the thrust force to be larger than that in more energetic sea states. The experiments suggest that the inclusion of pitch-controlled, variable-speed blades in physical (and numerical) tests on such types of structures is crucial, highlighting the importance of pitch motion as an important design factor.

Review on Fixed and Floating Offshore Structures. Part II: Sustainable Design Approaches and Project Management

“…Some of the newer offshore platforms contain advanced technologies derived from existing offshore platforms employed in oil and gas development. Some wind turbines have foundations designed based on other platforms like semisubmersibles [213][214][215][216][217][218][219][220]. For breakwater and wave energy devices, they require shallower water depths.…”

“…The sea fasteners, grillages and load-spreading components are necessary to distribute the stresses. They are designed depending on the type of structure and adopted sea fastening techniques [213][214][215][216][217]. Figure 10 shows some sea fasteners for offshore platforms.…”

“…The lifting, transportation, installation, design, fabrication, and commissioning of these offshore platforms must all be carefully planned to meet these goals [193][194][195][196][197][198][199][200][201][202][203]. The foundation of this semi-submersible in deeper waters requires excellent payload integration [204][205][206][207][208][209][210][211][212] for minimal motion responses across all degrees of freedom (DoF) due to the direction of the superstructure [213][214][215]. Hence the need for more understanding of the offshore structures, with the types of applications reviewed in Part I [5].…”

Investigations into Motion Responses of Suspended Submersible in Internal Solitary Wave Field

“…Cui et al [11] conducted experimental studies on the moored structure and obtained the motion responses and mooring tensions of the floating structure under the action of the ISW. Moreover, Sara et al [12] conducted a laboratory experiment to simulate the motion responses of the SPAR wind turbine. For the submerged structure, Wang et al [13,14] carried out experimental studies on the interaction effect between the ISW and a fixed underwater slender body in the stratified flume and revealed the relationships between the fixed structure and the ISW fluid field.…”

Analysis of FPSO Motion Response under Different Wave Spectra

“…With the continuous deepening of ocean research, the study of the interaction between waves and structures has great scientific significance [1]. Meanwhile, the nonlinearity of realistic ocean waves is becoming stronger, and the movement laws are also becoming more complex.…”