An investigation of the long-term deposition of graphite dust particles on turbine blades by mesh-deformation method

Abstract

The persistent accumulation of radioactive graphite particulates on turbine surfaces presents a critical operational challenge for high-temperature gas-cooled reactor (HTGR) systems. This investigation employs high-fidelity numerical simulations integrating discrete phase modeling with mesh deformation methods to systematically examine particulate deposition dynamics and their subsequent impact on turbine cooling effectiveness. A comprehensive deposition framework accounting for multiphase particle-wall interactions (elastic rebound, adhesion, multilayer stacking, and shear-induced resuspension) was established, complemented by the development of predictive model for accumulated deposition mass. Computational results reveal a non-monotonic relationship between particle size and deposition: sub-5μm particulates exhibit extensive deposition patterns primarily driven by adhesion forces, while larger particles are more likely to undergo resuspension due to drag forces. Elevated blowing ratios (M = 2.0) were found to reduce deposition rates by 7–22 %. Lower deposition height enhances the effectiveness of film cooling, while higher deposition height suppresses it. However, overall, the influence of deposition on cooling is limited. The developed predictive model for maximum accumulated deposition mass exhibits good predictive performance (R² = 0.99), and elucidates the influence of key parameters of particles and film cooling. This study reveals the long-term deposition behavior of particles on turbine blades and provides valuable insights for the safety analysis of HTGRs.