Session: 09-03-02 Tidal Energy: Hydrodynamics

Paper Number: 125312

125312 - Preliminary Numerical Assessment of Marine Turbines With Flexible Blades Using a Reduced Order Model 

Some remote towns and insular regions in Ecuador are still not connected to the national grid, which could be benefited by harnessing alternative renewable energy sources. In 2021, 78% of the 32600 GWh consumed nationally was produced using hydropower and less than 1% (100 GWh) with solar and wind farms. A previous feasibility study of the Ecuadorean Oceanic region and rivers to generate electricity found that the Galapagos Archipelago region has up to 16 kW per meter of swell waves, with a small variability throughout the year. Regarding the tidal energy, there are a limited number of in situ measurements that suggest that some estuaries are 6 to 20 meters deep and have stream velocities of up to 4 m/sec, but that last less than one hour. Although waves and tidal energy seems promising, only tidal technology could be deployed in the short term due to its maturity level to harness its energy.    

The main challenge of the energy extraction process is to select a small low maintenance tidal turbine that maximizes its energy production with a negligible environmental impact, especially on marine animals and sedimentation. The low-maintenance goal could be achieved with technology that increases the mean time to failure of turbine blades and drive trains by mitigating power and loads fluctuations associated with the larger scales of the turbulent tidal stream flow, which also interacts with the seabed and wave-induced currents. One promising alternative is the use of passive morphing blades, Viola et al demonstrated that for a 1.5 MW tidal current turbine with preloaded torsional springs and operating on a constant shear flow with 8% of turbulence intensity is possible to reduce these fluctuations by 40-80% by using low order models, numerical simulations, and experimental tests. However, there is no evidence of their effectiveness when operating with fast load fluctuations. In this regard, some shape-morphing concepts and materials have been evaluated to reduce blade loads for helicopters and wind turbine industries. The potential technical solutions are span-wise or chord-wise blade expansion and twist morphing, which continuously varies the angle of attack over the span of the blade using smart, anisotropic or elastomeric or multistable material that form the material of the blade skin.

The goal of the present work is to explore the feasibility of implementing a reduced order model to capture blade deformation in OpenFOAM framework to assess the performance of the Oxford tidal turbine with different types of morphing blade technology.

Presenting Author: Ruben J. Paredes ESPOL Polytechnic University, Escuela Superior Politécnica del Litoral, ESPOL

Presenting Author Biography: Dr. Rubén Paredes obtained his degree in Naval Engineering from the ESPOL Polytechnic University of Ecuador in 2006. He completed his MSc. at the University of Sao Paulo and in 2013 he obtained his doctorate in Ocean Engineering at the Stevens Institute of Technology. His PhD focused on fluid-structure interaction problems involving hydroelastic response using smoothed particle hydrodynamics. He was a postdoctoral researcher at the Massachusetts Institute of Technology-MIT for three years. Since 2016 he is a Full Professor of Fluid Dynamics and Ship Dynamics at ESPOL University. Currently, he is leading a research project with the goal of designing a zero-emission HSC for the Galapagos.

Authors:

Ruben J. Paredes ESPOL Polytechnic University, Escuela Superior Politécnica del Litoral, ESPOL
Paul S. Zambrano ESPOL Polytechnic University
Jose Rolando Marin Lopez ESPOL Polytechnic University
Hrvoje Jasak University of Cambridge