CAREER: Control of Vortex Breakdown in High-Reynolds Number Rotor Flows with Secondary Vortex Structures

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This project seeks to study and reduce the negative impact of blade tip vortices on rotor-based systems such as wind turbines, gas turbines for energy production or aircraft propulsion, and rotorcraft. Currently these systems suffer from underperformance due to an inability to control or diffuse the high-energy content of the blade tip vortex. A major aspect of the project is the large-scale experiments in a unique high-wind hurricane simulator facility at Florida International University that enables flow-similitude and realistic application of the results to full-scale rotor-based systems. Such educational training is vital to increase the pool of experimental thermal-fluids engineers that can continue to improve the efficiency of energy systems for the benefit of society. The proposed large-scale experiments will test new theories and create new knowledge of high- Reynolds number blade tip vortex breakdown using secondary vortex structures created by synthetic jets and chord-wise wall oscillations. The intellectual significance is a semi-empirical model that describes the characteristics of secondary vortices (e.g. length/ time scales, vorticity) necessary for vortex breakdown to occur, as well as its impact on turbulent kinetic energy, which is believed to induce blade structural vibration. The flow will be measured using stereoscopic particle image velocimetry techniques and analyzed using proper orthogonal decomposition (POD) as well as three-dimensional flow reconstruction from an array of two-dimensional measurement planes. These methods are unique for large-domain high Reynolds number flows. They will be used to shed light on blade tip vortex energy content/ POD modes, as well as to advance the field of experimental vortex dynamics particularly at high Reynolds numbers.