Numerical Investigation of Hydrogen-air Deflagrations in a Repeated Pipe Congestion

Emerging hydrogen energy technologies are creating new avenues for bring hydrogen fuel usage into larger public domain. Identification of possible accidental scenarios and measures to mitigate associated hazards should be well understood for establishing best practice guidelines. Accidentally released hydrogen forms flammable mixtures in a very short time. Ignition of such a mixture in congestion and confinements can lead to greater magnitudes of overpressure, catastrophic for both structure and people around. Hence understanding of the permissible level of confinements and congestion around the hydrogen fuel handling and storage unit is essential for process safety. In the present study, numerical simulations have been performed for the hydrogen-air turbulent deflagration in a well-defined congestion of repeated pipe rig, experimentally studied by [1]. Large Eddy Simulations (LES) have been performed using the in-house modified version of the OpenFOAM code. The Flame Surface Wrinkling Model in the LES context is used for modelling deflagrations. Numerical predictions concerning the effects of hydrogen concentration and congestion on turbulent deflagration overpressure are compared with the measurements [1] to provide validation of the code. Further insight about the flame propagation and trends of the generated overpressures over the range of concentrations are discussed.