Numerical Simulation Of Flammable Gas Explosions In Confined Rooms Built-in Obstacles

A large number of accidental gas explosions have happened every year and caused great loss and casualty. Therefore, the research of the flammable gas explosions becomes an important problem to be solved in the field of safety technique.In research methods, experiments cannot provide the rules due to lack of experiment ground, instruments and finance support However, with the development of computer technology, numerical simulation has become one of the most important research methods on flammable gas explosions, and has been used widely.The theoretical model of homogenous turbulent combustion flow has been formed based on the time-averaged equations of homogenous reaction flow, k-ε turbulent model and EBU-Arrhenius combustion model in this article. The two-dimensional numerical simulation of the premixed gas of propane/air in confined rooms built-in obstacles has been carried out through SIMPLEC scheme.In order to prove the mathematical model, the process of the flammable gas explosions has been simulated. Compared with the data of the experiments, the calculation error is within 10%. And the results demonstrate that the numerical simulation is in good agreement with the corresponding experiments.The main conclusions of the present paper are as follows:(1) The obstacle-induced disturbance at the flame front is negligible at the early-ignited stage of the flammable gas. When the flame propagates near the obstacles, the change of flame front happens obviously. With the enhancement of height of obstacles, the flame front is distorted strongly, which results in the rapid increase of flame velocity. And with the increase of the number of obstacles, the flame front that pulled farther will cause the raise of flame velocity too. The positive feedback mechanism of mutual acceleration among obstacle, turbulent flow and flame is explained.(2) The obstacle-induced effects are negligible in the closed vessels for the final explosion pressure, however they are very important for flame front, velocity field, pressure field, which will provide proof for the reasonable collection of the equipment in the confined rooms.(3) The overpressures reach the maximum near the outlet in vented vessels without obstacle. However, with the increase of blockage rate of obstacles, the overpressure becomes larger in vented vessels built-in obstacles.