A Simplified Sequential Coupled Simulation Framework for Floating Offshore Wind Turbines: A Case Study of a 15 MW TLP Turbine

Abstract

Tension-leg platform (TLP) horizontal-axis wind turbines (TLP-HAWTs) have become increasingly important in deep-water offshore wind energy development. However, their performance is strongly affected by coupled platform motions induced by wind and wave loads, making fully coupled simulations a critical prerequisite for accurate performance assessment. Conventional fully coupled approaches often struggle to balance computational efficiency and numerical fidelity. In this study, a simplified sequential coupled modeling framework is proposed based on the commercial solvers OrcaFlex and STAR-CCM+. In this framework, OrcaFlex is employed to simulate the hydrodynamic response of the floating platform, and the resulting platform motions are subsequently imposed as prescribed inputs in high-fidelity CFD-based aerodynamic simulations. Based on the proposed framework, a series of case studies of a 15 MW TLP-HAWT are conducted to investigate the effects of wind-induced and wave-induced platform motions on aerodynamic performance. The results indicate that wind-induced platform motions have a negligible impact on local inflow conditions and vortex intensity, and their influence on mean blade loads and wake topology can be safely ignored under rated conditions. In contrast, wave-induced motions significantly enhance unsteady aerodynamic loads, intensify vortex shedding, alter torque distribution along the blades, and increase wake turbulence intensity as well as velocity deficit. These findings suggest that wave-induced platform dynamics dominate the unsteady aerodynamic response and wake evolution of TLP-HAWTs under rated conditions, while wind-induced motions play a secondary role. The results provide valuable insights for reduced-order modeling, control strategy development, and the design optimization of efficient floating offshore wind turbines.

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