Injection characteristics and fuel-air mixing process of ammonia jets in a constant volume vessel

• A three-stage behavior of tip penetration in ammonia jets are proposed. The and methane have similar S , α fuel mole fractions at jet axis. hyperbolic decays concentrations the axis confirmed. Fuel increase with increased P inj but reduce a . Ammonia show distinct flammable mixture distributions. direct-injection gaseous is possible way to engines meet scenario zero-carbon emission. In this study, for first time, injection characteristics fuel–air mixing process investigated. Schlieren system employed characterize macroscopic including angle. Besides, quantitatively measured by LIBS investigate processes. According time evolutions penetration, behavior, namely t, t 0.5 (t-τ) 0.25 dependence corresponding early stage injection, quasi-steady after two times duration respectively, proposed mechanisms discussed detail. effects both ambient pressures on angle, as well concentration distributions pressure leads increases decreases opposite, indicating that development governed injection-to-ambient ratio. comparisons between conducted. results they quite penetrations angles, nearly equivalent However, equivalence ratios significantly lower than those jets, leading jets.