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To enable wind energy to surpass fossil fuels, the power-to-cost ratio of wind turbines must be competitive. Increasing installation capacities and wind turbine sizes indicates a strong trend toward clean energy. However, larger rotor diameters, reaching up to 170 m, introduce stability and aeroelasticity concerns and aerodynamic phenomena that cause noise disturbances. These issues hinder performance enhancement and social acceptance of wind turbines. A critical aerodynamic challenge is flow separation on the blade's suction side, leading to a loss of lift and increased drag, ultimately stalling the blade and reducing turbine performance. Various active and passive flow control techniques have been studied to address these issues, with passive techniques offering the advantage of no external energy requirement. High-lift devices, such as leading-edge slats, are promising in improving aerodynamic performance by controlling flow separation. This study explores the geometric parameters of slats and their effects on wind turbine blades' aerodynamic and acoustic performance. Using an adequate turbulence model at Re = 106 for angles of attack from 14° to 24°, 77 slat configurations were evaluated. Symmetric slats showed superior performance at high angles of attack, while slat chord length was inversely proportional to aerodynamic improvement. A hybrid method was employed to predict noise, revealing slat-induced modifications in eddy topology and increased low- and high-frequency noise. This study's main contribution is correlating slat-induced aerodynamic improvements with their acoustic effects. The directivity reveals a 10–15 dB reduction induced by the slat at 1 kHz, while the slat induces higher noise at higher frequencies. [ABSTRACT FROM AUTHOR]

The interaction between a flowing fluid and the transmission mains is in relation with the applied pressure level as well as the sought structure lifetime. The numerical approach developed in this study is based on a global modeling of the fluid and the deformation of the duct under transient conditions. The viscous tangential stress is expressed using a mixed polynomial development representing the variation of the radial profile of the fluid speed. The resolution of the obtained system of equations is carried out using the method of the characteristics coupled with the finite differences method. In the case of a Newtonian fluid, the results were compared to the experimental data of Holmboe and the theoretical ones of Zielke. This comparison allowed confirming the validity of the adopted calculation scheme. An extension of calculations in a similar way was carried out for the same installation in the case of a linear viscoelastic fluid. [ABSTRACT FROM AUTHOR]