Cavitation and solid particle erosion in a needle valve: A multiphase flow analysis and experimental validation

The synergistic failure mechanism induced by cavitation and solid particle erosion poses a significant challenge to the durability of fluid machinery components operating under high-pressure, multiphase flow conditions. This study investigates this synergistic phenomenon through a case study of a needle valve within a heavy fuel oil injector. A comprehensive numerical approach, integrating the SST κ-ω turbulence model, the Mixture multiphase model, and the Discrete Phase Model (DPM), was employed to analyze the transient interaction between phase change and particulate erosion during the valve opening process. The results identify the small-lift stage (lift <0.146 mm) as critical for cavitation damage, with peak vapor volume fractions reaching 0.38 in the sealing clearance and 0.95 near the nozzle walls. Concurrently, erosive wear exhibits a dynamic transition: at small lifts, wear localizes below the seat sealing line (maximum rate: 4.72 × 10 −5 μm/s), while at larger lifts, intensified swirling flow shifts severe wear to the needle’s first guide surface (maximum rate: 3.79 × 10 −3 μm/s). Transient analysis elucidates the migration mechanism of cavitation zones, linking it directly to the evolution of vortex structures in the flow field. The numerical model was validated against a 300 h heavy fuel oil bench test, with the simulated patterns of cavitation and wear distribution showing strong agreement with experimental observations, thereby confirming the synergistic failure mechanism. This work provides fundamental insights into the multiphysics interaction in microscale clearances and offers a validated methodology for failure prediction and design enhancement of critical sealing components in fluid machinery.