Interaction between wind turbine wakes and sand transport in a wind-sand environment

The siting of onshore wind farms has shifted from populated areas to desert and Gobi regions, where land costs are lower and noise pollution is minimal. As a result, turbines operate in wind-sand environments for extended periods. This study uses the Actuator Line Method (ALM) and Large Eddy Simulations (LES) to model wind turbine operations and flow fields, while the Multiphase Particle-in-Cell model simulates sand particle behavior. We investigate the effects of sand particles on turbine wake structure, energy distribution, and particle dispersion in a uniform incoming flow with mixed particle sizes. Snapshot Proper Orthogonal Decomposition (SPOD) analysis reveals that sand particles diminish the scale of the wind turbine wake structures. The lower-order modes exhibit a reduced contribution of energy to the flow field under sand-laden conditions compared to clean incoming flow. The particles reduce the wake flow velocity, the magnitude of the Reynolds principal stress, and the fluctuation amplitude of the Reynolds shear stress within the wake region. Particles passing near the blade tip travel along the wake periphery, exhibiting an initial expansion followed by a contraction in the near-wake region. Within the wind turbine wake, sand particles exhibit intricate winding motions, with smaller particles displaying more complex trajectories. A triangular region of reduced sedimentation forms on the ground approximately 10D downstream of the turbine, compared to the case without a turbine.