The influence of surface-wall roughness on hydrocyclone performance

The impact of hydrocyclone design and operation on particle separation has been extensively studied. However, scant attention has been paid to wall surface roughness, despite its relevance to industrial scenarios. This study investigates the influence of surface-wall roughness on hydrocyclone performance through Computational Fluid Dynamics (CFD) modeling and experimental analysis. Flow properties and particle separation characteristics between smooth and rough-surfaced hydrocyclones at various flow rates were investigated. CFD analysis reveals a threshold surface-wall roughness above which underflow water recovery significantly increases. Additionally, the axial, tangential, and radial velocities, as well as pressure distribution profiles, exhibit distinct trends for smooth and progressively rough hydrocyclones. Experimental studies were conducted on 75 mm diameter hydrocyclones, 3D-printed with three different degrees of surface roughness for water-only and 5% solids conditions. The experimental observations support the trends predicted by CFD. Rough-surfaced hydrocyclones demonstrate significantly higher underflow solids recoveries, with values increasing up to 58%, compared to 46% for smooth-surfaced hydrocyclones at a flow rate of 1000 mL/s. At the highest flow rate of 1500 mL/s, rough-surface hydrocyclones show a 27% higher underflow solids recovery than smooth designs. Additionally, rough-surfaced hydrocyclones achieved higher underflow solids concentration at increased flowrates compared to smooth hydrocyclones, with concentration ratios ranging from 1.36% to 2.2% compared to 1.44% to 1.93% for smooth surfaces. These findings underscore the complex interplay between flow dynamics and particle separation in hydrocyclones, highlighting the potential of surface-wall roughness to enhance separation performance. These findings are important in maintaining and improving hydrocyclone performance in industrial applications requiring dewatering applications and high solids recovery.