Experimental tests of inhomogeneous hydrogen deflagrations in the presence of obstacles

Explosion venting is a frequently used measure to mitigate the outcome of deflagration in closed environments. Despite the effort to improve engineering formulas and CFD tools used to predict the vent area needed to meet the desired enclosure protection, work has still to be done to reliably predict the outcome of a vented gas explosion. Blind-prediction exercises recently published by the HYSEA project show a large spread in the predictions by engineering models, including semi-empirical correlations and computational fluid dynamics (CFD) tools. University of Pisa performed experimental tests in a 25 m3 facility in inhomogeneous conditions and with the presence of simple obstacles constituted by plates bolted to HEB beams. The present paper is aimed to share the results of hydrogen dispersion and deflagration tests and discuss the comparison of maximum peak overpressure generated with different blockage ratio and repeated obstacles rows. Description of the experimental setup includes all the details deemed necessary to reproduce the phenomenon with a CFD tool.