Numerical simulation of triple shock behavior of gaseous detonation

A numerical analysis of performed on the nonsteady two-dimensional behavior of self-sustaining detonations. In order to produce realistic two-dimensional structures during propagation in a finite width channel, an initially assumed plane one-dimensional Chapman-Jouguet detonation was perturbed by locating up to five pairs of exothermicity spots in the passage of the detonation. The most interesting feature of the simulation was the number of triple shock waves existing after a certain time of transition from plane to periodically nonsteady two-dimensional structures. In other words, the final number of transverse shock waves becomes mostly two, which are nearly irrelevant to the assumed number of initial exothermicity spots. Details of the disappearance of several transverse waves during their rearrangement were clearly observed and are discussed. In addition, despite considerable deviation of the instantaneous propagation velocity from from the C-J value, the average of such oscillations was close to the C-J value. Thus, the results of the simulation provided the numerous features observed in the present gaseous detonations experiments. The numerical schemes utilized were the explicit first-order Van Leer and second-order MacCormack methods. The effect of artificial viscosity was examined and found to affect the transition to fully developed detonation.