Influence of hydrodynamic processes on apparent flame velocity in accidental explosions

Abstract

The main impact factor of an accidental explosion is explosive pressure, the numerical value of which is determined by the magnitude of the apparent flame velocity during explosive combustion of an explosive mixture. Therefore, the issues related to predicting the apparent flame velocity in deflagration explosions are the main ones when considering the problem of ensuring explosion resistance of buildings and structures and investigating accidents accompanied by explosions. Relationships are presented that confirm the unambiguous dependence of explosive pressure on apparent flame velocity. It is shown experimentally that in a deflagration explosion in free space, laminar combustion of the mixture occurs at first, so the flame front is flat and smooth, and at a certain distance from the ignition source, there is turbulization of the mixture moving in front of the flame front, and the explosive combustion becomes turbulent. The dependence determining the flame acceleration in an accidental explosion is given. It is experimentally shown that there is no rapid cessation of explosive combustion and flame arrest at the central initiation of a spherical explosive cloud of stoichiometric concentration. The methodology described in this article for determining the apparent flame velocity in deflagration explosions allows a fairly accurate prediction of the potential threat posed by explosive facilities and installations in the surrounding area.

Keywords

• deflagration explosion
• explosion safety
• explosive mixture
• flame speed
• emergency explosion
• viscosity coefficient
• diffusion coefficient
• thermal diffusivity coefficient