Effects of blowing/suction slot distribution on the transient tunnel aerodynamics of high-speed maglev trains

Abstract

High-speed maglev trains operating at 600 km/h are subjected to severe transient aerodynamic disturbances when traversing tunnels, which may compromise operational safety and passenger comfort. Active blowing/suction flow control has emerged as a promising approach for mitigating tunnel-induced aerodynamic effects, whereas the influence of slot distribution topology on control performance remains insufficiently understood. To address this issue, four onboard blowing/suction configurations with identical total opening area, namely, rectangular, slit, 3-slot, and 6-slot layouts, are proposed and systematically evaluated. Three-dimensional compressible unsteady Reynolds-averaged Navier–Stokes equations coupled with the Re-Normalization Group k–ε turbulence model are solved using the sliding-mesh approach to capture the transient train–tunnel aerodynamic interactions. The results demonstrate that all configurations effectively suppress pressure-wave propagation, reduce aerodynamic loads, and weaken slipstream velocities. The overall control performance follows the order: rectangular > 3-slot ≈ 6-slot > slit. Among the examined layouts, the rectangular configuration achieves the highest mitigation efficiency by concentrating jet momentum near the nose stagnation region and tail wake core, thereby enhancing pressure wave attenuation and wake pressure recovery. In contrast, the slit and decentralized multi-slot configurations exhibit reduced effectiveness due to momentum dispersion and weakened flow-control authority. Compared with the baseline, the rectangular layout reduces the peak pressure at the train nose and mid tunnel by 16.4% and 16.0%, respectively, decreases the lateral force amplitude of the head car by 19.3%, and lowers the maximum slipstream velocity by 31.0%. This study further elucidates that local jet momentum flux density, rather than total flow rate or opening area, dominates pressure wave attenuation efficiency under different slot distribution configurations. It also figures out the relationship between slot topology and aerodynamic control effectiveness, which complements the existing research framework of topology design for active flow control in high-speed maglev tunnel aerodynamics.