Computational analysis of erosion in Savonius Tidal Turbines for near-shore sites.

Abstract

Deploying Savonius Tidal Turbines (STTs) in shallow, low-velocity near shore environments offers a viable alternative to conventional turbines, but their economic feasibility is threatened by erosion from cavitation and Solid Particle Impingement (SPI). This study analysed STT blade erosion characteristics using a two-step methodology based on Poole Harbour reference data. Global flow behaviour was modelled via 3D transient Computational Fluid Dynamics (CFD), while localised wear hotspots were evaluated using a 2D CFD Discrete Phase Model (DPM) coupled with the Oka erosion model. The analysis revealed that STTs face negligible cavitation risk due to low tip speed ratios, making SPI the primary mode of degradation. Further, unlike high-velocity turbines, maximum abrasive wear on near-shore STTs concentrates near a flow stagnation region due to increased, localised particle impingement. Driven by this stagnation point effect, this erosion is focused on the upstream surface of the returning blade facing away from the centre. By extending erosion analysis methodologies to low-velocity near-shore STTs, these findings establish an initial spatial mapping framework to identify high risk wear regions on the blades, helping guide future material reliability and structural durability research for near-shore tidal deployments.