Aerodynamic redesign and computational fluid dynamics–discrete phase model evaluation of a high-clearance side-suction system for highway median cleaning

Abstract

A vehicle-mounted side-suction system was investigated for removing particulate debris from highway median strips while retaining the road clearance required for traffic-compatible operation. The system combines a multi-branch suction assembly with a streamlined converging nozzle. Steady Reynolds-averaged simulations using the shear stress transport (SST) k-omega model were coupled with Lagrangian particle tracking at a relative vehicle speed of 60 km/h and a moving-ground boundary. A 13.25-million-cell mesh was selected, and full-scale stationary hot-wire measurements were used to assess the continuous-phase velocity field. Thirteen equal injection surfaces represented a 1.3 m unilateral cleaning width. The redesigned nozzle removed the principal internal recirculation and increased the spanwise average suction velocity from approximately 44 to 52 m/s. Increasing the outlet-pressure magnitude from 8 to 14 kPa raised the constant-density array-averaged capture efficiency from 71.7% to 89.4%. A 100 mm clearance retained 78.8% capture while preserving greater road margin than the 60 and 80 mm cases. Ideal-gas calculations at −10 to −14 kPa reduced the absolute capture estimates by approximately 4.15-4.27 percentage points while preserving the pressure-ranking trend. Additional moving-ground sensitivity calculations showed that capture decreased at higher vehicle speed mainly because of shortened particle-flow interaction time rather than weakened suction velocity. The results establish design trends for a high-clearance side-suction architecture and quantify the moderate correction required when local compressibility is included.