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The Computational Fluid Dynamics (CFD) Laboratory

Research On the Cutting Edge  Cavitation in
                              Tidal Turbines

                                                  Prof. Steven Frankel and his lab team are working to
                                                  improve the performance of tidal power-driven turbine
                                                  blades that produce renewable energy in the deep seas

                                                 What: The Computational Fluid Dynamics (CFD)           How: Tidal turbines present a
                                                Laboratory focuses on the development and               new form of renewable energy
                                                implementation of high-precision numerical              technology. Tidal energy, also
                                                and physical models and on building turbulent-          called “lunar energy,” converts the
                                                flow simulations for application in numerous            moon’s gravitational pull on the
                                                areas, including aerodynamics, aeroacoustics,           oceans’ waters into electricity. Tidal
                                                cardiovascular, combustion, and multiphase              turbines’ operation is similar to that
                                                flows. CFD approaches are used primarily to solve       of wind turbines, but they are placed
                                                equations governing the behavior of fluids (such as     underwater, harnessing a reliable,
                                                air, water, etc.) using a numerical computer-assisted   yet underused, source of energy.
                                                method. Turbulence is an irregular state of fluid       The technology is still in its infancy;
                                                motion characterized by chaotic changes in pressure     one of its challenges, encountered
                                                and flow velocity. One of its familiar manifestations   by the hydrokinetic industry during
                                                is during flights, when passengers are asked to         its application, is cavitation—a
                                                fasten their seatbelts due to unexpected turbulence.    phenomenon in which the evaporation
                                                The computational simulation of turbulent flows         process, designed to turn water into
                                                presents a unique set of challenges, because of the     gas under decompression, leads to the
                                                wide range of lengths and time scales associated        formation of small vapor-filled cavities
                                                with turbulence; these require very precise             inside the turbine. The cavities cause
                                                numerical methods, mathematical models, and             corrosion, due to their collapse once
                                                high-performance computing. The CFD Lab currently       the local pressure increases, and have
                                                addresses several multidimensional problems             an adverse effect on turbine blade
                                                requiring such numerical methods, models, and           performance. The CFD Lab team is
                                                simulations.                                            testing passive and active methods of
                                                The growing global need for renewable energy has        strategic control to reduce cavitation
                                                led to the development of underwater turbines that      and improve blade structure, as part
                                                are powered by the natural rise and fall of the tides.  of a project supported by the EU’s
                                                One of the lab’s major research projects examines       Horizon 2020 program.
                                                cavitation in these turbines.

                            18 | MEgazine | Faculty of Mechanical Engineering
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