A novel pressure relief space angle for tunnel hood vented holes to mitigate micro-pressure wave at maglev tunnel exit

Purpose Aiming to address the drastic amplification of micro-pressure waves (MPWs) produced as 600 km/h high-speed maglev trains pass through tunnels, this study develops a mathematical model focused on the pressure relief space angle (θ) via the asymptotic linear method (ALM) for tunnel hood vented hole design, which provides theoretical and engineering support for relevant aerodynamic optimization. Design/methodology/approach First, the pressure relief space angle (θ) is clearly defined, which unifies geometric parameters including vented hole open ratios, position and quantity into a spherical projection area ratio. Then, by coupling the three-dimensional compressible unsteady Navier–Stokes equations with the k-ε turbulence model and combining the sliding mesh technique, the evolution characteristics of the initial compression wave (ICW) and MPW under different vented hole designs are numerically simulated. Findings A linear relationship between pressure relief space angle integral S and gas emission mass GE, and a negative linear relationship between GE and ICW first pressure gradient peak PF are established. The optimal θ criterion is proposed, and Case 3 reduces MPW amplitudes by 18.95% and 17.52% at 20 and 50 m from the tunnel exit, enabling rapid inverse design and saving computing resources. Originality/value This study innovatively defines the pressure relief space angle to unify multiple vented hole geometric parameters, constructing a novel mathematical model between pressure gradient and θ based on ALM. It realizes rapid inverse design from target MPW mitigation rate to vented hole parameters, significantly saving computing resources and providing a new theoretical tool and engineering basis for aerodynamic optimization of 600 km/h maglev tunnel hoods.