Effect of static rupture pressure on internal overpressure characteristics during petroleum fuel-air venting explosion process: A small-scale experimental study

A small-scale experimental system for venting explosions of petroleum fuel-air mixtures was constructed. Venting explosion tests of petroleum fuel-air mixture tests were conducted under different static rupture pressures (PST). The experiments obtained the overpressure characteristics under various PST conditions and classified the venting explosion modes. The experimental results indicate that the overpressure-time curves can be categorized into three modes and five typical stages, characterized by seven overpressure peaks. These overpressure peaks are attributed to the burst of vent cover (Δp1), the acceleration of unburnt gas venting (Δpun), the reduction of flame speed caused by collision between reflux gas and flame surface (Δpred), the flame venting acceleration (Δp2), the external explosion (Δp3), the Helmholtz oscillation (Δphel) and the coupling of unburnt gas acceleration and flame venting (Δpun&Δp2). When 0 kPa ≤ PST ≤ 5 kPa, the maximum peak is Δpun, whereas when 10 kPa ≤ PST ≤ 140 kPa, the maximum peak is Δp1. After the burst of vent cover, a dramatic transient occurs, specifically following the sequence of ‘venting of flame inducing negative overpressure-external gas reflux-collision of reflux gases with flame front-intensified internal combustion leading to positive overpressure’, culminating in Helmholtz oscillations. All the overpressure parameters are closely related to PST.