Springing Response of a Tension-Leg-Platform Wind Turbine Excited by Third-Harmonic Force in Nonlinear Regular Wave

The springing responses of a tension-leg-platform wind turbine (TLPWT) excited by the third-harmonic force of an extreme regular wave are investigated using an integrated (Aero-Hydro-Mooring) numerical model developed and presented in this paper. The model comprises a hybrid hydrodynamic model, which employs fully nonlinear potential theory (FNPT) for wave kinematic prediction and nondiffracting potential theory (NDPT) for wave force prediction, to simulate extreme wave and predict associated wave forces accurately and efficiently. Numerical simulation is carried out for the interaction of a floating TLPWT with waves. The focus is on the TLPWT motions, principally excited by higher-order harmonic wave forces. In particular, the springing responses generated by the third-order force at the triple wave frequency in regular waves are investigated, together with the wind turbine responses and tensions in the mooring lines.