Aerodynamic performance and wind-induced effect of large-scale wind turbine system under yaw and wind-rain combination action

Abstract

Blade yaw will change aerodynamic performance of large-scale wind turbine structure, especially under rainstorm conditions. Structural responses and stability of large-scale wind turbine system during rainstorm are more complicated due to the impact force of rainstorm on the structural surface and its influences on the incoming turbulence. In this study, the 5 MW wind turbine tower-blade system which was developed by Nanjing University of Aeronautics and Astronautics (NUAA) was used as the research object. Firstly, the surrounding wind field of the 5 MW wind turbine tower-blade system under different yaw angles (0°, 5°, 10°, 20°, 30° and 45°) was simulated by the computational fluid dynamics (CFD) technology based on the wind-rain two-way coupling algorithm. Secondly, the wind-rain coupling synchronous iteration was carried out by adding the discrete phase model (DPM). Based on numerical simulation results, the influencing law of yaw angle on wind-driven rainfall, additional acting force of raindrops and rain-induced pressure coefficient was discussed. The velocity flow line, turbulence energy strength, raindrop running speed and trajectory action mechanism on the structural surface in wind-rain coupling field was disclosed. Moreover, the distribution laws and fitting formula of wind-rain equivalent pressure coefficient under different yaw angles were constructed. Finally, large-scale wind turbine tower-blade coupling model under different yaw angles was constructed by combining the finite element method. Structural responses, buckling stability and ultimate bearing capacity of the large-scale wind turbine system with considerations to different yaw angles under wind condition and wind-rain condition were discussed. Results demonstrated that yaw angle can affect aerodynamic force and comprehensive stress performance of the wind turbine system significantly. The wind-rain load enhances structural responses of the system, and decreases the overall buckling stability and ultimate bearing capacity of the wind turbine. Main conclusions not only can provide references for accurate load evaluation under extreme complex conditions, but also are conducive to deepen understandings on the action mechanism of wind-rain load.