Slurry erosion degrades components in hydroelectric, mining, petroleum, chemical, and aerospace applications when solid abrasive particles entrained in fluid flows impact wetted surfaces. Components such as turbine blades, pump impellers, pipelines, and valves face shortened service life, increased maintenance, and economic losses when particulate ingress cannot be fully eliminated. Slurry erosion depends on interacting variables including particle size and shape, impact velocity and angle, slurry concentration, turbulence, and material properties. Laboratory rigs are commonly used to study these factors because they allow controlled parametric variation and accelerated testing relative to costly field trials.
Jet-type rigs are valued for flexibility in controlling velocity, impact angle, and slurry delivery. A recurring challenge across rig types is efficient and repeatable particle entrainment into the fluid stream. Existing approaches include premixed slurry circulation with pressurised or pump-driven systems, Venturi-assisted partial premixing, and gravity-assisted post-mixing. Each approach has trade-offs in complexity, flow stability, and operational cost.
The primary objective was to develop and experimentally evaluate a simplified Venturi-based slurry jet erosion test rig capable of introducing dry particles into a flowing liquid stream without pressurised slurry chambers or external vacuum ejectors. The secondary objective was to demonstrate the apparatus' ability to distinguish representative erosion behaviour of a ductile metal (brass) and a brittle metal (cast iron) across variations in impingement angle, particle size, and slurry concentration.
Brass was selected as the representative ductile material because ductile alloys commonly display plastic-deformation–dominated wear processes (ploughing, micro-cutting, extrusion), with literature indicating peak erosion often near 30° impingement. Grey cast iron (CI) was chosen as the representative brittle material because graphite flakes and higher carbon content promote crack initiation, brittle fracture, and chipping—mechanisms that typically produce maximum erosion near 90° impingement.
Specimens were prepared as 25 mm × 25 mm × 6 mm rectangular samples. Bulk chemical composition was verified by optical emission spectroscopy and reported in the paper's tables; pre-test surface features were documented qualitatively by scanning electron microscopy (SEM) to establish initial references. Detailed phase identification or localized elemental mapping were beyond the study scope.
The apparatus uses a modified Venturi concept to generate a localized static-pressure reduction at a throat, which passively entrains dry erosive particles introduced via a funnel. Key geometric parameters reported include an inlet diameter of 25 mm and a throat diameter of 8 mm. The diverging segment of the Venturi was removed in the design to reduce flow disruption, lower pump load, and focus the impact stream on the specimen.
A single-stage centrifugal pump rated at 30 L/min circulates water through the system. The rig operates as a recirculating system: after impingement particles collect in the reservoir and are re-entrained; continuous stirring in the reservoir reduces sedimentation. A bypass valve and a secondary control valve enable discharge regulation and flow stabilisation during tests. The specimen was held at a fixed stand-off distance of 20 mm from the nozzle exit and impingement angle was adjusted by repositioning the specimen holder.
During operation the pump drives water through the converging Venturi section so that velocity increases and static pressure drops at the throat. Dry particles fall from the funnel into this low-pressure region and are entrained into the stream toward the nozzle and specimen. The configuration enables controlled adjustment of flow velocity, particle concentration, and impact angle without pressurised feeding or vacuum assistance.
The design choices—removing the diverging section and using passive Venturi entrainment—aim to reduce operational complexity, lower maintenance needs from settling and sedimentation, and avoid the infrastructure required for pressurised premixed systems.
River sand of defined particle-size fractions served as erodent. The study varied particle size, slurry concentration, and impingement angle while maintaining jet speed constant. The experimental programme focused on comparative erosion responses between brass and CI to evaluate the rig's operational capability rather than comprehensive metallurgical analysis. The rig allowed repeatable positioning and flow regulation using the bypass valve and continuous reservoir stirring to maintain uniform slurry distribution.
Observed erosion patterns followed expected ductile-versus-brittle behaviour. Brass exhibited maximum erosion at an impingement angle of 30°, consistent with dominant plastic deformation mechanisms such as ploughing and micro-cutting under oblique impact. Cast iron displayed peak erosion at 90°, consistent with brittle fracture, crack initiation, and chipping under near-normal impact.
The authors estimated kinetic energy threshold values required for erosion initiation for both materials and correlated these estimates with experimental observations. Exact threshold values and their calculation details are reported in the article; the present summary notes only that threshold estimates supported the interpretation of onset behaviour observed experimentally.
Qualitative SEM of post-erosion surfaces supported identification of distinct erosion mechanisms. For brass, SEM images showed features consistent with material removal via shear and plastic flow; for cast iron, images showed evidence of fracture, crack propagation, and detached fragments. Pre-erosion SEM images were used as baselines to contrast the erosion-induced morphologies. The SEM observations were qualitative and intended to support mechanism identification rather than provide exhaustive microstructural quantification.
The developed apparatus demonstrated reasonably consistent operation and produced repeatable comparative erosion behaviour under the selected laboratory conditions. The Venturi-assisted particle entrainment method successfully introduced dry particles without pressure chambers or external vacuum systems. Continuous stirring and bypass flow regulation helped minimise sedimentation and stabilise discharge flow.
The external reservoir showed superficial corrosion from prolonged water exposure; the authors reported no internal degradation that affected slurry circulation, particle entrainment, flow regulation, or erosion measurements during testing.
This work presents a preliminary evaluation focused on demonstrating the rig's capability to produce controlled and comparative erosion responses for ductile and brittle metals. The experimental programme prioritized operational capability and comparative outcomes rather than exhaustive metallurgical or compositional characterisation. Detailed phase-level analyses and extensive parametric mapping were outside the stated scope.
Overall, the modified Venturi-based rig provides a simplified and lower-complexity option for laboratory-scale slurry erosion testing that passively entrains dry particles, enables control of key parameters, and distinguishes characteristic ductile and brittle erosion mechanisms under the tested conditions. The article states that all relevant data are provided in the paper and supporting information.