Longitudinal stability analysis of piston-driven pathological detonation wave

Pathological detonation is a non-ideal detonation that cannot effectively support the propagation of detonation waves due to other physical or chemical factors offsetting part of the chemical heat release. It is common in the practical processes, and the study on propagation stability of the detonation is of great significance. A single-step global reaction model was adopted to analyze the propagation stability of pathological detonation waves. Reduction of the reactant molar quantity decreased the overall system volume, introducing a negative-work effect that enables the pathological detonation regime. The process was numerically simulated using the one-dimensional reactive Euler equations, which couples chemical energy release with flow-field dynamics. A high-order finite difference method combined with a high-resolution flux-splitting scheme ensured accurate resolution of shock fronts and detailed reaction-zone structures. Parametric variations in piston-driven speed and activation energy were introduced to represent the effects of external mechanical forcing and intrinsic chemical reactivity, respectively. Comparative analyses of temporal evolution across parameter sets revealed the coupling mechanism between piston-driven flow dynamics and chemical kinetics. Further examination of the spatiotemporal distributions of temperature, pressure, and reactant mass fraction elucidated the link between detonation stability and the internal structural evolution of the reaction zone. The effects of piston-driven speed and activation energy on the stability of pathological detonation wave are systematically investigated, and the relationship between the stability of detonation wave and the reaction zone structure is analyzed. The results show that the pathological detonation is more unstable than the ideal detonation wave under the same reaction exothermic conditions. The increase of piston-driven speed is beneficial to the stability of the pathological detonation wave, while the increase of activation energy can lead to the instability of the pathological detonation wave. The high-frequency and low-amplitude oscillation of overdriven pathological detonation has little change in the structure of the reaction zone; the low-frequency and low-amplitude oscillation of detonation wave under the condition of strong solution is caused by the alternation of two configurations of strong solution in the reaction zone. The low-frequency and high-amplitude oscillation characteristics of overdriven pathological detonation are characterized by the alternating occurrence of reaction zone structures such as weak solution, strong solution and overdriven solution.