Effects of area density of a hinged inertial cover on H2/CH4/air deflagrations in a vented chamber

• Published in: Fuel (Guildford) Vol. 374; p. 132479
• Main Authors: Guo, Jin, Huang, Shikai, Wang, Fang, Xu, Caijun, Wu, Zelong, Zhang, Fan, Wu, Binhua
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 15-10-2024
• Subjects: Flame; Hinged vent panel; Hydrogen/methane/air explosion; Overpressure; Hinged vent panel; Overpressure; Hydrogen/methane/air explosion; Flame
• ISSN: 0016-2361
• DOI: 10.1016/j.fuel.2024.132479

•Effects of area density (Ws) of a hinged inertial cover on vented H2/CH4/air deflagrations were studied.•The opening angle at the time of tout decreases with an increase in Ws.•In the test with higher Ws, the external fireball becomes more flattened.•In tests at χH2 = 0.8, pred and pext increase sharply with an increase in Ws from 0 kg/m2 to 2.7 kg/m2.
Explosion venting is the most commonly used technique to reduce the hazard from accidental deflagration of combustible gases. Since less attention is paid to the influence of inertial vent on vented H2/CH4/air deflagration, the effects of area density (Ws) of a hinged inertial cover on the pressure profile and flame behavior during H2/CH4/air deflagration, with hydrogen volume fraction in fuel (χH2) being 0.5 and 0.8, were investigated by covering the vent using aluminum plates with various thicknesses. The results show that the interval between ignition and the moment the flame just travels through the vent (tout) is almost independent of Ws, but the opening angle of the panel at the time of tout is closely related to Ws. For a given χH2, the opening angle at the time of tout decreases with an increase in Ws. For a certain Ws, the opening angle of the panel is smaller for χH2 = 0.8 in comparison with the tests at χH2 = 0.5. In the test with higher Ws, the external fireball becomes more flattened. In tests at χH2 = 0.5, p3 induced by acoustic oscillations dominates the internal overpressure, but p2 resulting from the external explosion becomes the dominant pressure peak at χH2 = 0.8. The maximum reduced overpressure (pred) and maximum external overpressure (pext) are almost independent of Ws at χH2 = 0.5. However, in tests at χH2 = 0.8, pred and pext increase sharply with an increase in Ws from 0 kg/m2 to 2.7 kg/m2, but there is relatively little variation in pred and pext as Ws continues to increase from 2.7 kg/m2 to 24.3 kg/m2. Except for the test with Ws = 0 kg/m2, for a specific Ws, pred and pext at χH2 = 0.8 are always greater than those at χH2 = 0.5.