Experimental investigations of the fluid mechanics involved in wind turbines at very high Reynolds number - Marcus Hultmark, Princeton
Marcus Hultmark, Associate Professor in the Department of Mechanical & Aerospace Engineering at Princeton University
Abstract: Wind turbines and wind farms present unique challenges—fluid mechanically—as they combine extremely high Reynolds numbers with additional time scales imposed by the rotation, and three-dimensional effects. This implies that resolved numerical solutions are too computationally expensive and investigations in conventional wind tunnels are impossible due to the flow speeds and rotational rates needed in order to satisfy the dynamic similarity requirements. At Princeton, we achieve the conditions a large wind turbine experiences, experimentally, by compressing the air around a model-scale turbine up to 238 bar. This yields conditions similar to those experienced by a field-sized turbine using a model that is only 20 cm in diameter. High pressure enables tests at high Reynolds numbers but at low velocities, which implies that realistic non-dimensional frequencies can be tested even with such a small model. This unique feature is used both to study rotating wind turbines and their wakes, as well as the unsteady aerodynamics that are involved in these machines.
About: Marcus Hultmark is an associate professor in the Department of Mechanical and Aerospace Engineering at Princeton University, and he is the director of the Princeton Gas Dynamics Lab. His research interests include a variety of problems related to fluid mechanics, with focus on problems involving turbulence, such as heat and mass transfer as well as drag reduction and wind energy. Theoretical work is combined with experimental studies, and an important part of his research program is the development and evaluation of new sensing techniques to investigate these phenomena with high accuracy, including velocity, temperature and humidity sensors. He was awarded the 2016 Air Force Young Investigator award, the 2017 NSF Career award and the 2017 Nobuhide Kasagi Award. He is co-founder of two MEMS based startup companies, both formed around innovations from his research lab.