Developing an empirical model for ducted tidal turbine performance using numerical simulation results

This article studies the effects of viscous loss, flow separation, and base pressure for ducted turbine designs using computational fluid dynamics (CFD) simulations. Analytical model coefficients for inlet and diffuser efficiency and base pressure coefficient parameterize these effects and have been identified from CFD results. General trends are that the inlet efficiency is nearly unity for the simulated designs; the diffuser efficiency has a significant impact on performance and is degraded by flow separation; and that the base pressure effect can provide a significant performance enhancement. Geometric features influencing each of the aforementioned parameters are identified and a regression-based model has been developed to predict ducted turbine performance.