Assessing Spacing Impact on the Wind Turbine Array Boundary Layer via Proper Orthogonal Decomposition

Abstract. A 4 × 3 array of wind turbines was assembled in a wind tunnel with four cases to study the influence based on streamwise and spanwise spacings. Data are extracted using stereo particle-image velocimetry and analyzed statistically. The maximum mean velocity is displayed at the upstream of the turbine with the spacing of 6D and 3D, in streamwise and spanwise direction, respectively. The region of interest downstream to the turbine confirms a notable influence of the streamwise spacing is shown when the spanwise spacing equals to 3D. Thus the significant impact of the spanwise spacing is observed when the streamwise spacing equals to 3D. Streamwise averaging is performed after shifting the upstream windows toward the downstream flow. The largest and smallest averaged Reynolds stress, and flux locates at cases 3D × 3D and 6D × 1.5D, respectively. Snapshot proper orthogonal decomposition is employed to identify the flow coherence depending on the turbulent kinetic energy content. The case of spacing 6D × 1.5D possesses highest energy content in the first mode compared with other cases. The impact of the streamwise and spanwise spacings in power produce is quantified, where the maximum power is found in the spacing of 6D × 3D.