Investigation on vented ethanol-gasoline vapor explosion characteristics initiated via single and dual sparks

Abstract

Although vented explosions initiated via dual sparks have already been investigated to model accidental multi-explosions events, the vent coefficient (Kv) and vent location factors have not been analyzed together as far. Hence experiments were carried out in a self-designed vented channel contained single/dual sparks to investigate the effect of Kv and dimensionless vent location (X/D) on vented ethanol-gasoline vapor explosion overpressure and flame propagation. Results indicated that Helmholtz oscillation appeared in overpressure with small Kv, and the oscillation amplitude would be enhanced as X/D increased. Tulip flame appearance depended not only on Kv but also on X/D. The flame downstream of the vent that propagated with a low velocity oscillation and the cellular flame under small X/D, where Kv was positively correlated with cell size. The Pmax and Kv were both positively correlated with a power function (Pmax=aKvb) under the cases of single and dual sparks. The coefficient a increased as X/D rose, and index b always closed to 1. A correlation between the flame velocity (v) vs Kv following membrane burst under single and dual sparks conditions was derived based on energy equation. And the unburned gas flow velocity ratio (vdc/vsc) following membrane burst was obtained, which can explain quantitative relationship between experimental dual/single flame velocities (vd/vs≈0.5). Two ratios difference came from the spherical flame propagation.

Keywords

• Ethanol-gasoline
• Dual sparks
• Vented explosion
• Vent coefficient
• Vent location