Hydrokinetic turbine models in complex channel topography: local scour, sediment transport and device performance.

Craig Hill, Jessica Kozarek, Fotis Sotiropoulos, Michele Guala

Tuesday 30 june 2015

12:00 - 12:15h at Antarctica (level 0)

Themes: (T) Special session, (ST) Marine renewable energy

Parallel session: 5D. Special session: Marine Renewable Energy

Accelerating marine energy development requires investigating the interactions between the engineered environment and its surrounding physical and biological environment. The complex and energetic physical environments desired for such energy conversion installations provide difficulties for efficient and sustainable device designs. One area of investigation focuses on the interactions between the channel topography and substrate material and its impacts on the structural integrity of hydrokinetic devices, as well as device impacts on local scour and sediment transport. Laboratory experiments on such interactions performed at St. Anthony Falls Laboratory, University of Minnesota, USA provide an indication of how small-scale hydrokinetic devices can inform device developers and provide robust data for computational model validation to address the interactions between energy conversion devices and the physical environment. Model axial-flow current-driven three-bladed turbines (rotor diameters, dT = 0.15m and 0.5m) were installed in open channel flumes with both erodible and non-erodible substrates. Device induced local scour was monitored over several hydraulic conditions and material sizes. Additionally, synchronous velocity, bed elevation and turbine performance measurements provide an indication into how channel topography influences device performance. For comparison, a complimentary set of experiments was performed in a realistic meandering outdoor research channel with active sediment transport to investigate device performance in asymmetric channel flow environments. The suite of experiments in rectangular and meandering channels with stationary and mobile substrates provides an in-depth investigation into how axial-flow hydrokinetic devices respond to channel complexity, and how they impact local and far-field sediment transport characteristics. Results will be discussed in context with addressing uncertainties surrounding physical environment impacts of current-driven turbines and methods for informing future device development and control strategies.