The effect of pipeline sudden contraction structure on the deflagration characteristics of hydrogen-methane-air.

Based on the visualized gas cloud explosion pipeline test platform, the influence of the sudden contraction structure on the deflagration characteristics of the hydrogen-methane-air gas cloud is investigated. The results show that the changes of flame propagation velocity, explosion overpressure, and flame temperature after deflagration of the premixed gas cloud all present three stages: rapid increase, rapid decline, and secondary acceleration caused by the sudden contraction of pipeline structure. The equivalence ratio significantly affects the hydrogen-methane-air detonation process in the sudden contraction of the pipe structure. As the hydrogen content increases, the flame propagation becomes faster and the explosion impact becomes greater. The formation of "Tulip" flame is closely related to the flame propagation speed. During the process of flame propagation, inertia dominates, causing the flame propagation speed to reach its first peak at the abrupt contraction structure. [Display omitted] • The effect of sudden contraction pipeline on premixed gas detonation is examined. • The detonation process of pre-mixed gas clouds undergoes three stages. • The speed of flame propagation is closely related to inertia. • The flame structure of the "tulip" is closely related to the flame speed. • The effect of hydrogen and equivalence ratio on deflagration is examined. [ABSTRACT FROM AUTHOR]