Particle image velocimetry (PIV) has been applied to measure the velocity profile within the near wake of a laboratory scaled model of a horizontal axis tidal turbine. Measurements have been taken for a number of arrangements to investigate the relative impact on the velocity profile of ambient conditions, the support structure, and energy extraction by the rotor.
In recent years, economic and ecological factors have caused a rise in the interest and research into various renewable energy technologies. Arguably, the general perception has been that such resources are seemingly abundant but limited in their exploitability due to intermittency and unpredictability. Nonetheless, a well documented exception is the tidal resource, which is both predictable and abundant (Bahaj and Myers, 2003; Bryden, Grinsted and Melville, 2004; Batten, Bahaj, Molland and Chaplin, 2006; Myers and Bahaj, 2007; Bahaj, Molland, Chaplin and Batten, 2007; Myers and Bahaj, 2020). Developers of horizontal axis tidal turbines have benefitted from the lessons learned by wind turbine developers in recent decades, leading to the installation of full-scale prototype devices. Though such prototypes have successfully demonstrated the concept of tidal energy, the installation of multiple devices within tidal farms at high energy sites will be necessary in order to maximize generation. Within each farm, energy yield from individual turbines and hence the farm as a whole will be a function of array density and spatial arrangement. Consequently, a detailed understanding of the flow field downstream of an individual device is a fundamental first step towards the design of tidal farms which are both spatially efficient and sustainable.
Past research has focused on the far wake of horizontal axis tidal turbines in an effort to reduce complexity and avoid potentially excessive scale effects within laboratory tests.
