Numerical Investigation of Detonation in Stratified Combustible Mixture and Oxidizer with Concentration Gradients

Hydrogen leakage in a closed space is one of the causes of serious accidents because of its high detonability. Assuming the situation that hydrogen is accumulated in a closed space, two-dimensional numerical simulation for hydrogen oxygen detonation which propagates in stratified fuel and oxidizer with concentration gradient is conducted by using detailed chemical reaction model. The concentration gradient between fuel and oxidizer is expressed by changing the number of hydrogen moles by using sigmoid function. Strength of discontinuity at the boundary is controlled by changing the gain of the function. The maximum pressure history shows that the behaviour of triple points is different depending on the strength of discontinuity between the two kind of gas. In without concentration gradient case, the transverse waves are reflected at the boundary because of the sudden change of acoustic impedance ratio between two kind of gas. In contrast, in with concentration gradient case, the transverse wavs are not reflected in the buffer zone and they are flowed into the oxidizer as its structures are kept. As a result, the confined effect declines as the strength of discontinuity between the two kind of gas is weakened and the propagating distance of detonation changes