Effects of initial pressure and temperature on the ignition and combustion characteristics of ammonia/hydrogen/air adopting turbulent jet ignition

Ammonia (NH₃) and hydrogen (H₂) mixture are expected to replace traditional fossil fuels in the transportation industry to achieve zero-carbon emissions. Adopting turbulent jet ignition (TJI) is a reliable way to enhance the ignition and combustion of NH₃/H₂. The present study aims to explore the effects of initial pressure and temperature on the ignition and combustion characteristics of NH₃/H₂ ignited by TJI. It can be found that the increased initial pressure reduces the jet velocity. Due to the joint effect of weakened turbulence and inherent flame propagation characteristics caused by the elevated pressure, the combustion duration is extended. However, the ignition performance can be enhanced by increasing the initial pressure. Improvement is reflected in the emergence of flame ignition mechanisms and the obvious radial propagation of jet flames in early development. The increase in initial temperature slightly increases the peak jet velocity, while the auxiliary H₂ in active mode will reduce the sensitivity of jet velocity to the initial temperature. Although the increased initial temperature has shown the promotion for achieving rapid ignition and combustion, there is no significant improvement in the ignition mechanism, the ignition is caused by accumulated heat and radicals provided by the reacted jet.