Impact of vertical-wind-rotor coupling in atmospheric boundary layer: A large wind turbine numerical demonstration

The aerodynamic response of rotating systems under oblique inflow is a long-standing fluid mechanics problem. Traditional analyses of horizontal-axis rotating systems in the atmospheric boundary layer generally assume purely axial inflow, yet real conditions involve oblique inflow, whose coupling with the rotor requires in-depth investigation. To thoroughly investigate the impact of vertical-wind-rotor coupling, this study uses the IEA 15 MW wind turbine rotating system under oblique inflow as a case study. Oblique inflow is realized by superimposing vertical wind on the horizontal free stream, with vertical wind speed as the control variable to evaluate its effect on aerodynamic performance under normal operating conditions. Based on this, a generated power prediction model incorporating the vertical-wind-rotor coupling effect is proposed. The results demonstrate that the impact of vertical wind on rotating system performance depends on specific wind condition parameters, with varying horizontal wind speed profiles and vertical wind speed directions causing distinct response patterns. Notably, vertical wind affects aerodynamic loads and power generation and may significantly alter blade tip response, necessitating consideration of the risk of blade-tower collision. Vertical wind and rotor tilt angle exert a coupled effect on generated power, essentially because the rotor tilt angle decomposes vertical wind speed into an induced velocity component perpendicular to the rotor plane. The generated power prediction model performs favorably under conditions with small absolute values of vertical wind speed and small rotor tilt angles. The findings provide a reference for aerodynamic performance studies of other rotating systems under oblique inflow.