A numerical study on laboratory-scale piloted turbulent jet flames of partially cracked ammonia

Partially cracking technology is considered a promising strategy to enhance ammonia (NH 3 ) combustion. Well understanding and modeling the reaction behavior of partially cracked NH 3 is important for its efficient and clean combustion. In the present work, quasi direct numerical simulations (quasi-DNS) are performed for the KAUST piloted turbulent flames of partially cracked NH 3 (flames D and F), which are identified as target flames in the TNF16 workshop. The predicted mean and root mean square ( rms ) profiles of temperature and major/minor species are compared with the experimental data in the physical and mixture fraction spaces. The comparisons demonstrate that the present quasi-DNS can well reproduce the mean and rms profiles in both the physical and mixture fraction spaces for flame D. While for flame F, good agreement can be achieved for the upstream and downstream locations. However, the local extinctions in the midstream regions have not been sufficiently reproduced. The statistics and analyses on combustion modes and their heat release contributions demonstrate that premixed and diffusion modes appear in the inner and outer layers, respectively, and the heat release contribution from each mode is comparable. This highlights the necessity of considering both the premixed and diffusion modes in large eddy simulations of the target flames. • Quasi-DNSs of piloted turbulent jet flames of PC-NH3 are performed for the first time. • The quasi-DNS results agree well with the experimental data for the flame D. • The local extinction in midstream regions of flame F is not well reproduced. • Premixed and diffusion modes appear in the inner and outer layers, respectively. • The heat release contributions of premixed and diffusion modes are comparable.