Characterizing the Transitional Behavior of Wind Turbine Wake From Near to Far Wake Regimes

Abstract

Knowledge of wind energy harvesting is an ever-growing process, and to meet the enormous energy demand, wind farms shall have a significant role. An efficient wind farm is required to have an in-depth knowledge of turbine wake characteristics. This article presents an experimental investigation of the wake expansion process defined by the transition of wake from near to far wake regimes. The study has been performed on models horizontal axis wind turbine (HAWT) composed of NACA 0012 profile, keeping the ratio of root chord to tip chord length is 5:2. A constant temperature hot-wire anemometer (HWA) has been used to examine the rotor’s fluctuating flow field. The subsequent time-averaged normalizes velocity deficit, and vortex shedding frequency are used for the flow characteristics. Time-averaged velocity deficit measurement suggests a drop in upstream velocity by 20–30% within the vicinity of rotor tip downstream of the rotor plane. The study shows that flow recovery is initiating from the near wake regime around 1.08R. Further, the spectral findings indicates the low frequency dominance within 4R (R being the rotor radius), and the Strouhal number falls close to 0.23. The present wind tunnel study on wake characteristics throws significant insight into further enhancing the WT wake modeling.