The current paper is an overview on previous and ongoing research carried out by the authors concerning the use of Computational Fluid Dynamics for the accurate classification of hazardous Ex areas generated by flammable gases, for the optimization of computational simulation of air-methane mixture explosions by using ANSYS CFX and FLUENT and for calibrating computational simulations of gas explosions using the Schlieren effect. These research works containing analytic studies have led to the observation of basic principles which come to support the benefit of computational approaches for estimating gas dispersion within technological installations in which are handled or stored flammable materials and in which there are likely to occur explosive atmospheres. Preliminary results have led to the idea of developing a computational method for assessing the hazardous area extent in case of gas leak explosions in confined spaces. The computational method intended to be developed has to be validated in the lab using an experimental chamber as domain for analysing accidental flammable gas leaks from transportation installations and for studying the formation, ignition and burning of air-flammable gas mixtures in confined spaces. Results obtained from physical experiments will be used for calibrating the mathematical models. Further, verification and validation of computational simulations carried out based on physical experiments will be performed by a comparative analysis of virtual results with the experimental ones. In the end, the mathematical model will be implemented on a small-scale reproduction of a confined industrial area with explosion hazard.

This paper aims to study the behavior of air-gas explosion systems, in terms of propagation speed of pressure wave and flame front, based on experimental measurements in a shock tube, in order to prevent accidental pollution with the combustion gases. The characteristic parameters of the explosion process determined using the shock tube, the velocity of propagation of the flame front, the speed of propagation of the wave of pressure, explosion pressure at various distances from the source of initiation, can be used in the preparation of explosion risk assessment studies for technological processes carried out in potentially explosive atmospheres. Taking the developed technical measures would make possible ensure both the explosion protection and the prevention of accidental pollution with combustion gases.

Nowadays, the transportation of hazardous substances required for various industrial works is a very common activity. In each national economy, safe transport of hazardous materials on land is an important issue. Much of these materials are either moved by trucks or trains. However, hazardous materials transportation is very likely to generate major accidents with irreversible consequences on surrounding population and on the environment along transportation routes. The current paper deals with analysis and simulation of the consequences of an explosion involving a truck transporting flammable gas cylinders materials. Consequence modelling involves the graphic representation or the calculation and estimation of numerical values which best describe the physical results of loss of containment scenarios which involve flammable/explosive/toxic materials with regard to their impact on surrounding assets or people. In the present study, state of the art software has been used for modelling and simulating the accident scenario, namely the initial fire and the subsequent explosion of the gas cylinders.

Methane is one of the most common gaseous fuels that also exist in nature as the main part of the natural gas, the flammable part of biogas or as part of the reaction products from biomass pyrolysis. In this respect, the biogas and biomass installations are always subjected to explosion hazards due to methane. Simple methods for evaluating the explosion hazards are of great importance, at least in the preliminary stage. The paper describes such a method based on an elementary analysis of the cubic law of pressure rise during the early stages of flame propagation in a symmetrical cylindrical vessel of small volume (0.17 L). The pressure–time curves for lean, stoichiometric and rich methane–air mixtures were recorded and analyzed. From the early stages of pressure–time history, when the pressure increase is equal to or less than the initial pressure, normal burning velocities were evaluated and discussed. Qualitative experiments were performed in the presence of a radioactive source of 60Co in order to highlight its influence over the explosivity parameters, such as minimum ignition energy, maximum rate of pressure rise, maximum explosion pressure and normal burning velocity. The results are in agreement with the literature data.

The naturally or industrially occurring flammable mixtures containing combustible gases or/and dusts represent a potential risk of explosion with major consequences on the environment and human personnel. Methane and coal dust are among the best known components able of leading to the formation of such mixtures either in coal mining activities or in different industries using coal dust as fuel. In order to assess the risk of explosion and the explosion evolution in such composite mixtures, the knowledge of the characteristic explosion parameters under standardized conditions is necessary. In this paper the maximum explosion pressure p max , maximum rate of pressure rise (dp/dt) max and explosion severity factor for methane-air mixtures, air-coal dust mixture and hybrid air-methane-coal dust mixture were determined in a standard 20 dm 3 spherical explosion vessel.