Experimental comparisons of dynamic properties of floating wind turbine systems based on two different rotor concepts

Abstract

a b s t r a c tThis article presents research findings on the response characteristic differences between the thrustmatched blade system (TMBS) and the geometry-matched blade system (GMBS), which utilize redesigned thrust-matched and original geometry-matched blades, respectively, both based on the OC3 spar-type floating offshore wind turbine (FOWT). Particulars of this research are to examine the unique dynamic response characteristics of the TMBS, which includes a better performance-matched rotor relative to the GMBS. The response behaviors of the TMBS and GMBS are compared and studied based on a sequence of wind and irregular wave scenarios to reveal the unique roles that the thrust-matched rotor plays in the dynamic response behaviors of the floating wind turbine system. Gyroscopic effects of rotor rotation are found weakened in the TMBS, and yaw oscillation in the TMBS is not solely excited by rotor rotation, unlike in the GMBS. Coupling effects between surge and pitch are found in both the TMBS and GMBS under combined wind-and-wave condition. Furthermore, restraining effects of wind loads on motions in the GMBS and TMBS are both evident at natural frequencies while show distinct behaviors at the wave frequency. It is observed from the experimental measurements that the tower-top bending moment of the TMBS shows similar oscillation characteristics as that of the GMBS but with larger oscillation amplitudes. Furthermore, it is found that tower-top shear force and axial rotor thrust of the TMBS show distinct exciting motivators and much larger oscillation amplitudes relative to those of the GMBS. For both the TMBS and GMBS, the tensions measured in mooring lines are found to be coupled by yaw motion for windonly cases while being clearly influenced by surge and heave couplings under integrated wind-and-wave load condition.

Experimental investigation of aerodynamic effect–induced dynamic characteristics of an OC4 semi-submersible floating wind turbine

“…As for the degree of accuracy of the model tests in this article, most of parameters and methods in our tests refer to the MARIN's tests 35 with some improvements. Detailed comparisons between our tests and the MARIN's tests can be found in the work of Duan et al 22,23 In recent years, a series of verifications of the MARIN's tests has been public 21,[43][44][45] and has proved that floating wind turbine model tests with geometry-similarity blades produced global performance data that properly emulated the desired full-scale responses and showed a reasonable trend of dynamic responses when moving from a no wind condition to an operating wind turbine condition, despite some differences in tip speed ratio and aerodynamic torque between the model and the prototype. In summary, a series of investigations in this article indicate that rotating-blades-induced aerodynamic loads play an important role in determining the dynamic characteristics of a semi-submersible floating wind turbine system.…”

“…20 In 2012, DeepCwind consortium 21 carried out a series of 1/50th scale model tests for three different platforms, including a tension-leg platform, a spar-buoy and a semi-submersible platform at the MARIN (Maritime Research Institute Netherlands). In 2014, Duan et al 22,23 carried out a 1/50th scale model test at the Deepwater Offshore Basin in Shanghai Jiao Tong University, in which an OC3 spar-type and an OC4 semi-submersible floating wind turbine were adopted. In 2014, a 1/50th scale Spar Torus Combination (STC) model test (an innovative combination of a wave power generation system and a spar-type floating wind turbine) was carried out by the Norwegian University of Science and Technology (NTNU) in the towing tank of the MARINTEK.…”

Comparisons of the dynamical characteristics of a semi-submersible floating offshore wind turbine based on two different blade concepts

“…This concept was implemented in 2013, and some of the anterior FOWT model tests have been re-conducted at the MARIN (Goupee et al, 2014). In the same year, geometrically similar blades and redesigned performance-matched blades were also applied to a spar-type and semi-submersible FOWT model test at the SJTU (Shanghai Jiao Tong University) Deepwater Offshore Basin (Duan et al, 2016b).…”

“…Although the observed aerodynamic performance was improved using the performance-matched model blades, the model blades were inevitably overweight relative to the design specifications both in MARIN and SJTU model tests (Duan et al, 2016b;Goupee et al, 2014;Gueydon, 2016), which may induce a change in the dynamical characteristics of the FOWT models. Both the 'adjustable wind speed method' with geometrically matched (geometrically similar) blades and the 'redesigned performance-matched blades method' have their own known respective disadvantages.…”

Dynamic response sensitivity of an offshore wind turbine for multiple load condition

“…To simulate the pitching motion of floating platform, it used onshore wind turbine model with inflow with oscillating wind speed that simulates relative wind speed change from wind turbine's fore-aft pitching motion [7]. Particulars of this research are to examine the unique dynamic response characteristics of the thrust-matched blade system, which includes a better performance-matched rotor relative to the geometry-matched blade system [8]. The aim was to design a suitable substructure, such as a jacket or multipile, to support a 5 MW wind turbine in 33 m deep water for the Korean Southwest Offshore Wind Farm.…”