STUDY ON EFFECT OF SYNTHETIC JET ON VORTEX-INDUCED MOTION OF SPAR-TYPE FLOATING OFFSHORE WIND TURBINES
Vortex-induced motion(VIM)problem is one of the important factors causing fatigue damage in the mooring systems and cables of floating offshore wind turbines(FOWT).The present work studies the suppression law of synthetic jet on the VIM of the Spar-type floating offshore wind turbine(FOWT)through an active control technology.The influences of the jet velocity ratio(γIR,jet velocity ratio to incoming flow velocity)and injection angle φ on the vortex-induced response,vortex-induced force,vortex shedding frequency and vortex structure are researched.It is found that the characteristics of vortex-induced response are closely related to the γIR and φ.Synthetic jets can effectively suppress the VIM of structures,and more specifically,the larger the γIR and the closer φ approaches the separation point,the better suppressing effective will behave.It is also found that the γIR reduces the frequency of vortex shedding,thereby keeping the oscillation frequency away from the natural frequency.The results show that the synthetic jet can effectively suppress the vortex-induced resonance of the Spar-type FOWT.The suppression mechanism is to unlock the vortex-induced resonance to achieve the suppression effect by reducing the frequency oscillation,rather than reducing the vortex-induced force.
offshore wind turbinesdynamic characteristicscircular cylinderssynthetic jetsactive control
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