The Impact of a Novel Groove Structure on Flow Transition and Erosion Resistance Characteristics in 90° Elbows

Severe localized erosion in 90 degrees elbows remains a critical challenge in gas-solid two-phase pipeline systems. This study proposes and investigates a novel grooved elbow design aimed at modulating flow transitions and significantly enhancing erosion resistance. Employing the Reynolds Stress Transport Model (RSTM) coupled with the Discrete Phase Model (DPM), a systematic numerical investigation is conducted to evaluate the effects of key groove geometric parameters, namely length, inner angle, number, and depth, on both hydrodynamic characteristics and particle erosion behaviors. The results reveal that the groove structures fundamentally alter the internal flow field by breaking down high-intensity longitudinal secondary-flow vortices into smaller, fragmented near-wall micro-vortices. This hydrodynamic modification effectively deflects high-energy particle trajectories and mitigates localized particle concentration. Quantitatively, under optimal configurations, the grooved elbow achieves a remarkable reduction in the severe erosion area by up to 78% and decreases the maximum erosion rate by approximately 40.1%, with only a moderate pressure drop penalty of 9.6%. Ultimately, this research provides a structurally simple, cost-effective passive flow-control solution to extend the service life of pipeline systems, presenting broad potential applications in chemical, energy, and hydraulic engineering.