Gradient-Based Design Optimization of a 5kW Ducted Hydrokinetic Turbine Using RANS CFD*

Building upon our previous study on ducted hydrokinetic turbine optimization, this study focuses on enhancing the performance of a 5kW ducted hydrokinetic turbine under real-world constraints. Starting with a foil-shaped duct and a turbine featuring a bulky hub to house a generator, we optimize the duct, hub, and blades to maximize efficiency. The geometry is represented by a CAD-based parametrization using an open-source Engineering Sketch Pad. The gradient-based optimization process is performed, evaluating the turbine performance using a RANS-based flow solver and computing the gradients for the optimization using the adjoint method. The optimized design is subsequently re-evaluated using a higher-fidelity flow solver, yielding approximately 50% hydrodynamic efficiency, higher than an unducted counterpart.