The Role of Active Flow-Control Devices in the Dynamic Aeroelastic Response of Wind Turbine Rotors

The significance of wind as a renewable source of power is growing with the increasing capacity of individual utility-scale wind turbines. Contemporary wind turbines are capable of producing up to 8 MW and consequently, their rotor sizes are rapidly growing in size. This has led to an increased emphasis on studies related to improvements and innovations in load-control methodologies. Most often than not, controlling the loads on an operational turbine is a precarious scenario, especially under high wind loading. The up-scaling of turbine rotors would thus benefit from a rationale change in load control through methodologies such as variable-speed stall, flexo-torsional adaptive blades, and active flow-control devices. This thesis work extends the capabilities of an aeroelastic code to provide a platform to analyze wind turbines with flow-control devices as active load control techniques. It also explores the effectiveness of such devices under rapid load-control scenarios relevant to benchmark turbines. Pre-determined rapid control actions such as pitching and trailing-edge flap actuation are implemented under nominal operating conditions. The benchmark turbine designed by National Renewable Energy Laboratory (NREL), which is an upwind three-bladed rotor rated at 5 MW forms the test bed for the current thesis study. The goal is to obtain an overall understanding of the aeroelastic rotor response of utility-scale wind turbines under rapid control actions, paying special attention to the power of actuation