Effects of CO addition on shock wave propagation, self-ignition, and flame development of high-pressure hydrogen release into air.

In this study, an experimental investigation is conducted to study the effects of CO addition (0%–7.5% vol.) on the self-ignition of pressurized hydrogen leakage. The result shows that more CO addition significantly decreases the likelihood of self-ignition inside the tube and the formation of self-sustained jet flame outside the tube. This can be mostly explained by the reduction of leading shock intensity inside the tube. Furthermore, CO addition effectively inhibits the flame propagation and development inside the tube. For pure hydrogen, the ignited flame quickly develops an intense flame spanning the tube width and eventually form a jet flame in ambient air. However, the H 2 –CO diffusion flame initiated approaching tube sidewall tends to propagate adjacent to the wall or be soon quenched with more CO addition. If the CO-weakened flame spouts to the tube exit, it may not survive the expansion at the tube exit and thus it is quenched. • The shock intensity is reduced in the presence of CO. • The critical pressure for self-ignition increases with CO addition concentration. • Shock intensity variation by CO addition is the main factor affecting self-ignition onset. • Small CO addition can effectively inhibit flame development inside the tube. • H 2 –CO flame spouting from the tube exit tends to be blown out. [ABSTRACT FROM AUTHOR]