Propagation characteristics and destructive mechanisms of detonation in bifurcated tubes

Detonation behaviors in bifurcated tubes are of significant interest in the petrochemical industry due to their impact on pipeline safety and design. This work presents an experimental investigation on detonation behaviors in both straight and bifurcation tubes under varying equivalence ratios. Five equivalence ratios (φ = 0.85, 0.9, 1.0, 1.1, 1.2) were adapted in the straight tube, while five bifurcation angles (α = 30°, 45°, 90°, 135°, 150°) with three equivalence ratios (φ = 0.9, 1.0, 1.1) were explored in the bifurcation tubes. Results indicate that, deflagration-to-detonation transition (DDT) occurs late in extremely lean-fuel or rich-fuel mixtures in the straight tube. When detonation cross over the bifurcation, both the velocity decrease ratio and pressure decrease ratio depend on the bifurcated angle, though they trends differ due to their distinct destructive mechanisms. Two destructive modes of detonation were observed downstream of the bifurcation at different angles: weakening and failure, attributed to diffraction and energy distribution. A transition length for detonation re-initiation was observed in the downstream of bifurcation, during which the detonation remained in an over-driven state. These findings provide crucial theoretical foundations and practical guidance for design of petrochemical pipelines.