Experimental study on effect of hydrodynamic parameters on abrasion damage of hydraulic concrete in submerged condition

This study presents an experimental and mechanistic investigation of concrete abrasion under submerged sand-laden jet impingement. Tests were performed across impact angles (20°–90°), velocities (10–20 m/s), distances (0.1–0.3 m), durations (0–8 h), and a fixed concrete compressive strength (48.8 MPa). An improved apparatus was developed, incorporating a flow isolation baffle to minimize external fluid interference and sloped bottom to ensure effective water-sand mixing. A quantitative particle replacement protocol was established to improve test consistency. High-resolution three-dimension scanning identified two abrasion regions: elliptical major region from jet impingement and parabolic minor region caused by wall jet. Multidimensional quantitative analysis revealed that impact angle primarily governs abrasion morphology via redistributing jet velocity components and enhancing flow asymmetry. With decreasing angles, the abrasion range elongated, peak depth shifted downstream (73 % at 45°), and eccentricity increased (0.93 at 20°). Peak depth (35.2 mm) and weight (251.9 g) occurred at 60°, reflecting a balance between jet momentum and flow resistance. Abrasion weight and volume followed near-cubic power-law trends with velocity (exponents: 2.91 and 3.02), highlighting the energy-dominated nature of the process. Increasing impact distance expanded abrasion range but reduced depth due to jet attenuation, with peak abrasion weight (251.9 g) at 0.2 m. Time-dependent growth followed power-law trends, while peak depth location and eccentricity remained angle-dependent. Proposed semi-empirical equations based on dimensional analysis predicted abrasion length and width with high accuracy (mean relative error < 4.05 % on experimental dataset). These results advance mechanistic understanding and offer predictive tool for abrasion-prone zones in hydraulic structure design and maintenance.