Using Large Eddy Simulation for understanding vented gas explosions in the presence of obstacles.

In this work, a validated Large Eddy Simulation model of unsteady premixed flame propagation is used to study the phenomenology underlying vented gas explosions in the presence of obstacles. Computations are run of deflagrating flames in a small-scale combustion chamber closed at the bottom end and open at the opposite face. A single obstacle is centred inside the chamber. Methane-air mixtures of various compositions (ranging from lean to stoichiometric and rich), and obstacles with different area blockage ratios (30, 50 and 70%) and shapes (circular, rectangular and square cross-section in the flow direction) are investigated. All cases are initialized from stagnation. The competition between combustion rate and venting rate allows explaining both number and intensity of the overpressure peaks observed.