Experimental Observation of Flame Propagation Behavior of Hydrogen Enriched Flames Upstream of a Flame Arrester Housing with Parallel Plates as the Arrester Element

Abstract

ABSTRACT The phenomenon of flame propagation in closed and semi-open ducts that have no obstacles is of interest due to the need to include alternative fuels into the energetic matrix. Tulip flames can develop under these configurations. Therefore, the behavior of flame propagation upstream of a flame arrester housing is relevant to assess the challenges of flame quenching under this configuration. The objective of this article is to investigate the effect of the effective Lewis (Leeff ) number, Zeldovich (Ze) number and initial pressure (p i ) on the flame propagation behavior upstream of a flame arrester housing with parallel plates as the flame arrester element. The Leeff and Ze numbers were varied between 0.60 and 1.36 and between 4.19 and 8.77 respectively. In addition, the initial pressure was varied from 40 kPa to 80 kPa. The mixtures considered involved natural gas, hydrogen, helium and air, which were stoichiometric in all cases. It was observed that the tulip flame developed in all cases, but with different positions of the tulip flame formation. This is important for the development and testing of flame arresters as the inlet velocity and pressure are influenced by this phenomenon. The maximum flame propagation velocities (V max ) and the maximum pressure ratios (p max /p i ) were also determined. It was found that V max decreased for higher values of the product Leeff ⨯Ze for all mixtures and initial pressures. Similarly, p max /p i decreased with increasing Le eff ⨯Ze for the initial pressures of 40 kPa and 60 kPa. A slightly different behavior was observed for pmax/pi at 80 kPa, which did not decrease significantly with higher Leeff ⨯Ze. Therefore, the flames were characterized by weak acceleration and moderate pressure ratios.