Effect of mole weight ratio of reaction on propagation of cellular detonations

Abstract

The propagation of two-dimensional cellular detonations is investigated numerically using a one-step reversible reaction model. The effect of the average mole weight ratio W B/ W A of the product and reactant on the one-dimensional Zeldovich–von Neumann–Döring (ZND) detonation and cellular detonation behavior is analyzed in detail. Several interesting cellular detonation phenomena are observed in the numerical simulations. These can be divided into five categories according to the cell patterns of detonation, i.e., regular, relatively regular, irregular, half-cell propagating, and decoupled detonation. The results indicate that differences in cell size under different values of W B/ W A modify the cellular detonation behavior. The ZND detonation parameters under various W B/ W A values are studied and related to the cell size. The results show that the reaction zone length and maximum heat release rate are clearly influenced by W B/ W A. Furthermore, for both ZND detonation and cellular detonation, the reaction zone length decreases as W B/ W A increases, which effectively reduces the cell size. To elucidate the effects of the reaction zone length on cell size, thermoacoustic instability theory is introduced to investigate the acoustic perturbations in the reaction zone. This allows the correlation between the propagation frequency and cell number along the width of the duct to be determined. Correlation analysis indicates that the cell number has a strong linear dependence on the perturbation frequency.