Effects of Non-uniform Blockage Ratio and Obstacle Spacing on Flame Propagration in Premixed H2/O2 mixtures

Abstract

Most of the current research in flame propagation and deflagration-to-detonation transition (DDT), including large and small-scale experiments, have analyzed the influence of obstacles uniformly distributed on the explosion severity. These uniform conditions are characterized by constant obstacle spacing, shape and blockage ratio (BR), and may not represent very well the layout of actual industrial facilities. Therefore, the objective of this study was to investigate the effects of varied BR in the peak overpressure and flame acceleration. A systematic analysis was conducted by varying layout parameters on a regular basis to examine what conditions favor the highest overpressure and minimal run-up distance when DDT is observed. Experiments were performed in a closed pipe with 38 mm internal diameter and an overall length to diameter ratio (L/D) equal to 73. The arrangement between two obstacles in the test vessel was varied in terms of blockage ratio (increasing, decreasing and equal) and obstacle distance (1D, 2D, and 3D). From the conditions tested, the increasing blockage ratio has a more significant impact on the overall maximum pressure and the DDT run-up distance.