Confinement-Exploiting Cross-flow Turbine Arrays Brian ...
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Confinement-Exploiting Cross-flow Turbine Arrays
Brian Polagye, University of Washington
ARPA-E SHARKS
Team Overview
Scott Jenne
Elena Blackman
Dr. Richard Wiebe
Dr. Mike Motley
Dr. Brian Johnson
Dr. Steve BruntonDr. Brian Polagye
Dr. Owen Williams
Dr. Jennifer Franck
Technical Overview‣ Control co-design of cross-flow turbine arrays with high confinement
– Exploit confinement, unsteady hydrodynamics, and inter-turbine interactions
– Rapid experimental optimization to full-scale validation through simulation
Experiments
Electrical Model
Est. LCOE
Powertrain efficiency
P, F
Laboratory Control Optimization
P
Control Update
Experiment (PIV)
Simulation
Validated Simulation
Structural Simulation
Full-scale pressure fields
Economic Model
Structural design
Full-scale Evaluation
New Candidate Geometry
ω(θ)
Economic Model
Prior Work‣ Three foundational elements
– Confinement: Betz limit exceeded in experiments1
– Control: Intracycle control experimentally demonstrated > 50 % increase in power output relative to fixed tip-speed ratio2
– Geometry: Preset pitch, chord-radius ratio, and blade count all affect turbine performance
‣ No prior work has identified potential for simultaneous optimization of these factors
– Consequently, we are likely unaware of substantial improvements that are possible for cross-flow turbines
1 McAdam, R.A., Houlsby, G.T. and Oldfield, M.L.G. (2013) Experimental measurements of the hydrodynamic performance and structural loading of the Transverse Horizontal Axis Water Turbine: Part 1. Renewable Energy, 59.
2 Strom, B., Brunton, S., and Polagye, B. (2017) Intracycle angular velocity control of cross-flow turbines. Nature Energy, 2. doi: 10.1038/nenergy.2017.103
Effects of blade number, chord-to-radius ratio, preset pitch angle, and Reynolds number on maximum CP
Project Impact
‣ Benefit to technology developers
– Highlight opportunities in design space
– Apply similar techniques to propriety systems with unsteady fluid dynamics to reduce LCOE (cross-flow turbines, oscillating foils)
‣ Benefit to site developers
– Highlight LCOE reduction potential for confinement-exploiting arrays for all turbine variants
– Motivate approaches to site development beyond micrositing for individual turbines
‣ Benefit to industry
– Potential to increase estimates for technically available resources at river and tidal current sites
Yang, Z., Wang, T., Branch, R., Xiao, Z. and Deb, M., 2021. Tidal Stream Energy Resource Characterization in the Salish Sea. Renewable Energy.
Anticipated Challenges‣ Challenge 1: What if full-scale LCOE is insensitive to
choice of geometry and control strategy?
– Impact: Unable to meet performance targets
– Mitigation: Rapid iteration with validated simulations (performance and flow fields) to identify problem and redirect efforts as early as possible
PIV 2D RANS
Dave, M., Strom, B., Snortland, A., Williams, O., Polagye, B. and Franck, J.A., 2021. Simulations of Intracycle Angular Velocity Control for a Crossflow Turbine. AIAA Journal, 59(3), pp.812-824.
Anticipated Challenges‣ Challenge 2: How can we ensure we haven’t
missed part of the geometric design space?
– Geometric space is vast and difficult to explore experimentally
– Mitigation: Bayesian experimental optimization to identify portions of design space with high uncertainty and potential for low LCOE
– Demonstrated potential to map coordinated control parameter space with 50% fewer experiments
Scherl, I., Brunton, S., and Polagye, B. (2021) Paramter modeling of a two cross-flow turbine array. 14th European Wave and Tidal Energy Conference, Plymouth, U.K., Sep. 5-9.
Path to Target LCOE
‣ Approach
– Step change increase in CP, utilizing potential and kinetic energy in moving water: CP > 1.3
– Maintain high generator and drivetrain efficiencies while employing intracycle control
– Limit CT increase to 1.5x (Compared to 3x increase in CP)
‣ Environmental and societal compatability
– Intracycle control reduces collision risk and noise: achieves high efficiency at relatively low average tip-speed ratio
– “On demand” migration and transportation corridors available shutting down sections of array
7
Tech to Market Plan
‣ Design use cases– Focus on river for remote communities, but
consider potential for large-scale river and tidal currents
– Target LCOE < 8 ¢ / kWh
‣ Demonstrate early-stage market benefits– Reduce need for “micro-siting” individual
turbines
– Apply turbine optimization framework to proprietary designs
‣ Commercialization barriers– Requires “high” confinement to achieve
LCOE targets – elevated environmental and economic risk for initial array