Experimental and Numerical Modelling of Pressure Piling using Homogeneous Explosive Mixtures

The design of electric valve actuators for explosion proof (Ex d) hazardous environments, whereby an explosive event must be contained, is examined in this study. Combustion within these small enclosed volumes is complex due to the irregular geometries developed in the design process, effectively producing a series of obstacles. These geometries lead to a scenario whereby combustion within the enclosed interconnected volumes produces the phenomenon known as pressure piling. A numerical method utilising OpenFOAM (Foundation), an open-source computational fluid dynamics (CFD) code, has been developed to simulate combustion within two interlinked vessels. OpenFOAM has not been validated extensively for simulating pressure piling. The numerical results are in good qualitative and quantitative agreement with a set of experimental data. A unique experiment conducted by the author, which introduces obstacles representing blockage ratios (BR’s) is presented. Understanding the mechanisms of pressure piling will eventually lead to improved design techniques to control the effects of the over-pressures produced by these types of internal geometries.