漂浮式海上风机(floating offshore wind turbine, FOWT)的结构运动对风机的气动特性产生复杂的影响，具体表现为叶片攻角的周期性变化、气动载荷的不稳定性以及功率输出的波动。该文首先对FOWT在六个自由度方向的运动分别展开研究，将结构运动化简为简谐运动，定量分析运动幅值、频率等因素对FOWT的气动特性的影响。进一步，基于叶素动量理论(blade element momentum, BEM)和多体动力学理论，采用风机一体化分析软件OpenFAST对FOWT开展了气动分析。之后，对简谐运动下风机的推力系数和转矩系数进行统计分析。此外，针对纵荡和纵摇运动下，FOWT受到的轴向气动载荷和气动转矩进行时域和频域的具体分析，进而对固定式和漂浮式的海上风机的发电功率和发电量进行比较。研究结果表明，六个自由度运动中，纵荡和纵摇运动对FOWT的推力和转矩的影响程度大于其他自由度运动。纵荡和纵摇运动的幅值和频率与FOWT的轴向气动载荷和气动转矩的波动变化相关。与固定式风机相比，纵荡和纵摇运动下的FOWT的发电功率产生的波动更剧烈，但总发电量变化较小。

Objective: Floating offshore wind turbines (FOWTs) experience irregular motion because of their unique structure under severe deep-sea conditions. The floating motions of the FOWTs exert specific effects on their aerodynamic characteristics, manifested in the periodic variation of the blade angle of attack, instability of aerodynamic loads, and fluctuations in power output. This study investigates the 6 degrees of freedom (DOF) motion of the FOWT, simplifies the complex floating motion to harmonic motion, and quantitatively analyzes the influence of different factors, such as amplitude and frequency on the aerodynamic characteristics. The power generation of the FOWT under the floating motions is determined, and the total energy output is calculated based on this. Methods: By utilizing the integrated analysis software OpenFAST, the aerodynamic characteristics of the FOWT under harmonic motion are investigated in this study. The blade element momentum theory is employed to compute the aerodynamic loads acting on the blades in OpenFAST. Meanwhile, the structural response of the FOWT is determined based on the structural dynamics. The coupled calculations are conducted based on Kane's method in multibody dynamics. The mass, stiffness, and damping matrices of the platform mounted on the wind turbine are defined within the ExtPtfm module of OpenFAST to establish a superelement model. Following the principles of structural dynamics, a time-history harmonic load is applied to the model to induce the harmonic motion of the FOWT. This study focuses on the NREL 5-MW baseline wind turbine as the subject of investigation. The thrust and torque coefficients of the turbine during harmonic motion are statistically analyzed. In addition, the axial aerodynamic loads and aerodynamic torques experienced by the FOWT under both surge and pitch motions are examined through time and frequency domain analyses, followed by a comparison of power output and energy generation between fixed and floating turbines. Results: The statistical analysis of the thrust and torque coefficients reveals that, for the surge motion with an amplitude of 5 m and a frequency of 0.1 Hz, the coefficients of variation for the thrust coefficient is 8 times greater than that of a fixed wind turbine, whereas the torque coefficient increases by a factor of 23. For the pitch motion with the same frequency and an amplitude of 5°, the thrust and torque coefficients increase by factors of 20 and 44, respectively. Time and frequency domain analyses of the aerodynamic loads acting on the wind turbine (both axial aerodynamic load and aerodynamic torque) indicate significant fluctuations in the aerodynamic loads under both surge and pitch motions, with additional components induced by the motion. Furthermore, the power generated by the wind turbine exhibits considerable fluctuations because of the effects of both surge and pitch motions. Conclusions: In the case of the wind direction being perpendicular to the rotor plane, both surge and pitch motions in all 6 DOFs have a more significant effect on the aerodynamic characteristics of the FOWT. Both surge and pitch motions cause periodic variations in the aerodynamic loads, with the amplitude and frequency of the motion influencing the nature of these fluctuations. Moreover, both surge and pitch motions lead to instability in power generation. However, the total energy produced over time remains largely unaffected.