Multiresolution Large‐Eddy Simulation of an Array of Hydrokinetic Turbines in a Field‐Scale River: The Roosevelt Island Tidal Energy Project in New York City

Abstract

Marine hydrokinetic (MHK) power generation systems enable harvesting energy from waterways without the need for water impoundment. A major research challenge for numerical simulations of field-scale MHK farms stems from the large disparity in scales between the size of waterway and the energy harvesting device. We propose a large-eddy simulation (LES) framework to perform high-fidelity, multiresolution simulations of MHK arrays in a real-life marine environment using a novel unstructured Cartesian flow solver coupled with a sharp-interface immersed boundary method. The potential of the method as a powerful engineering design tool is demonstrated by applying it to simulate a 30 turbine MHK array under development in the East River in New York City. A virtual model of the MHK power plant is reconstructed from high-resolution bathymetry measurements in the East River and the 30 turbines placed in 10 TriFrame arrangements as designed by Verdant Power. A locally refined, near the individual turbines, background unstructured Cartesian grid enables LES across a range of geometric scales of relevance spanning approximately 5 orders of magnitude. The simulated flow field is compared with a baseline LES of the flow in the East River without turbines. While velocity deficits and increased levels of turbulence kinetic energy are observed in the vicinity of the turbine wakes, away from the turbines as well as on the water surface only a small increase in mean momentum is found. Therefore, our results point to the conclusion that MHK energy harvesting from large rivers is possible without a significant disruption of the river flow.

DOE-ANOVA to Optimize Hydrokinetic Turbines for Low Velocity Conditions

“…Studies of HT for low velocity conditions have been performed for different applications like hydropower systems in irrigation channels [18], waterwheels and transverse horizontal axis turbines for moderate sized rivers [19] with ultra-low head turbines [15]. The interest in HT for tidal energy has materialized initiatives such as the Roosevelt Island Tidal Energy (RITE) project in the United States (New York) which utilized 30 HT in an array to produce 35 kW [20,21]. In Canada the Maine project used 15 HT of 500 kW to provide electricity for the urban area of east Maine [22].…”

Performance and Wake Characterization of a Model Hydrokinetic Turbine: The Reference Model 1 (RM1) Dual Rotor Tidal Energy Converter

“…Measurements in the wake of scaled single rotor turbines highlight the complex and turbulent fluid environment. Tools such as acoustic Doppler velocimetry (ADV) [8,12,[31][32][33][34][35], laser Doppler velocimetry (LDV) [5,7,24], particle image velocimetry (PIV) [5,7,10,36] and computational fluid dynamics (CFD) ranging from coupled blade element modeling (BEM) and CFD modeling of single, two and three turbine arrays [22] to high-fidelity large-eddy simulation (LES) [37][38][39] have enabled detailed descriptions of this complex wake flow, shear layer evolution, and interactions between wake vortex regions, including the breakdown of hub, tip and turbine support structure vortice [5]. A common theme has been the pronounced wake velocity deficit, a highly 3D flow structure that includes coherent hub and tip vortices, and an increase in turbulence intensity and anisotropy compared to ambient conditions.…”