Multi-objective Optimization of Horizontal Axis Wind Turbine Arrays: Impact of Spacing Distance on Noise Generation and Power Efficiency

This work explores the effect of spacing between co-axially positioned Horizontal Axis Wind Turbines (HAWTs) on their aerodynamic behavior and acoustic emissions under uniform inflow conditions. The aerodynamic simulations employ the Actuator Disk Method (ADM) integrated within an Unsteady Reynolds-Averaged Navier-Stokes (URANS) framework, utilizing the standard k-ε turbulence model to resolve near-wake turbulent structures. For noise prediction, the Ffowcs Williams-Hawkings (FW-H) acoustic analogy is applied using the Farassat-1A formulation on a permeable spherical surface surrounding the rotor to estimate the generated acoustic pressures. These pressure signals served as input sources for far-field noise computations based on the Linearized Euler Equations (LEE). The findings demonstrate that wake interactions significantly influence the downstream turbine's performance and acoustic output in multiple-turbine arrangements. A multi-objective optimization process was carried out to achieve a trade-off between energy production and acoustic emissions, identifying an inter-turbine spacing of 6D as an optimal configuration. The study also emphasizes the limitations of relying solely on single-turbine aeroacoustic models for wind farm analysis, underscoring the necessity of full-scale aeroacoustic evaluation when considering wake effects and acoustic interference among turbines.