Chin, ReyKelso, RichardBayron, Paul2025-07-312025-07-312024https://hdl.handle.net/2440/146441A comprehensive study of horizontal-axis wind turbines was conducted in a wind tunnel using high-frequency single-wire hotwire anemometry and multi-hole velocity probes. The investigation aimed to assess wind turbines’ performance and wake dynamics under diverse conditions and varying pressure gradients. Critical performance variables were parameterised to observe the fluctuations in wind turbine efficiency across different scenarios. The coefficient of power, a crucial non-dimensional parameter representing the extracted power relative to available wind energy, served as a primary performance parameter. The study involved measuring or calculating various statistical parameters in the wake of the wind turbine at different distances from the rotor. Parameters included mean streamwise, spanwise, wall-normal velocities, turbulent kinetic energy, and streamwise vorticity. Frequency analysis of the velocity signal enabled the examination of energy distribution among different flow structures and their development downstream under various operating conditions. Significant emphasis was placed on the wake streamwise velocity recovery, a critical factor influencing downstream wind turbines’ inflow and available power extraction. Turbulent kinetic energy was also a key focus, as it could impact the load experienced by the downwind wind turbine, thereby affecting its operational lifespan. Operating conditions were systematically varied, including the tip-speed ratio of the wind turbines, affecting tangential velocity at the blade tips relative to the incoming flow. The study revealed that increasing the tip-speed ratio influenced the velocity deficit distribution and wake recovery. Another crucial parameter that was varied during the experiments was the relative rotation direction between an upwind and a downwind wind turbine. The results indicated that relative rotation had a negligible effect on the downwind wind turbine’s wake streamwise velocity but significantly influenced performance and turbulent kinetic energy in the wake. Subsequent experiments looked into the effects of surrounding flow, particularly its pressure gradients. Three pressure gradient scenarios, adverse, favourable, and zero pressure gradients, were induced within the test section. The investigation explored how these pressure gradients affected different wake statistics, providing a broad understanding of wind turbine wakes and surrounding flow characteristics.enRenewable EnergyWind Turbine WakeTurbulenceThesis