Explosions of gasoline vapor/air mixture in closed vessels with different shapes and sizes

Abstract

This article reports the results of an experimental study on explosion characteristics of gasoline vapor/air mixture in closed vessels with different shapes and volumes (20-L sphere, 280-L rectangle, 1.15 m3 cylinder and 5.19 m3 cylinder) and different shapes but same volumes (straight rectangular tube and rectangular tubes with 1 branch, 2 branches, 3 branches and 4 branches) under conditions of low, medium and high initial gasoline vapor volume concentration. The maximum explosion overpressures pmax, the maximum rates of pressure rise (dp/dt)max and the deflagration indices KG are examined in comparison with similar data obtained in different shape and size vessels. The measured maximum rates of pressure rise and deflagration indices are strongly influenced by the shape and size of test vessels. When the other initial conditions are invariant, the maximum rates of pressure rise and deflagration indices in the spherical vessel are larger than that in rectangular tube and cylinder tube. When the vessel shapes are same or similar, with the increase of the vessel volumes, the maximum rate of pressure rise decreases, while, the deflagration index increases. When the test vessels remain same size but different shape, the maximum overpressure and maximum rates of pressure rise of the gasoline vapor explosions increased with the branch number of the rectangular tubes. The influence of flame velocity, structure and shape and even turbulence should be considered when the maximum rate of pressure rise and deflagration index of the explosions in a specific non-spherical vessel are determined.