Experimental study on the detonation characteristics in ammonia-hydrogen-air mixtures

Abstract

This study experimentally investigates the detonation characteristics of ammonia-hydrogen-air mixtures containing ammonia proportions up to 25 percent, focusing on fuel composition and initial pressure effects on detonation velocity, peak pressure, cellular structure, and critical detonation pressure. A 5000 mm detonation tube equipped with pressure sensors and smoked-foil was employed to analyze wave propagation dynamics. Results demonstrate that increasing ammonia content reduces detonation stability, amplifies velocity fluctuations and cellular irregularity. Peak pressure shows positive correlation with initial pressure but diminishes at higher ammonia concentrations due to dilution effects. The critical detonation pressure systematically rises with ammonia content, driven by its chemical inhibition. A dimensionless parameter D/λ was proposed to characterize the detonation limits. Experimental results demonstrated that all tested premixed gases exhibited D/λ ratios exceeding unity, indicating that the tube dimensions satisfy the minimum requirement for sustaining stable multi-headed detonation structures. These findings offer critical insights for optimizing ammonia-hydrogen fuel blends in practical combustion systems while mitigating detonation hazards. The work establishes quantitative relationships between ammonia fraction, pressure conditions, and detonation behavior, providing essential data for safe implementation of ammonia-based alternative fuels.