Simultaneous measurements of NH2 and major species and temperature with a novel excitation scheme in ammonia combustion at atmospheric pressure

This work reports the first 1D, simultaneous, laser-induced fluorescence (LIF) measurements of amidogen (NH2) radical concentration and Raman/Rayleigh major species temperature in laminar counterflow non-premixed premixed NH3/H2/N2–air flames. The instrument presents a novel excitation scheme for NH2, which add no complexity to existing instrument. NH2 LIF is excited by three Nd:YAG lasers, temporally stretched 500 ns using pulse stretcher, resulting total energy ∼ 1 J at 532 nm. spectra collected produced from photolysis NH3, an oxygen-free environment, match those obtained NH2-LIF signal sampled 620–630 nm, together with Raman signal, same collection hardware. weak absorption cross-section nm compensated high laser available, long allows repeated emission molecule, leading partial saturation region. A simplified model neglects quenching, contributions other species, but includes crosstalk H2, N2, NH3 proposed calibrated comparing 1D Chemkin simulation flame. Finally, this was validated more than 23 flames varying fuel compositions, strain rates, assess accuracy precision. overall agreement between measured simulated mechanism within 5%, single-shot detection limit below 100 ppm. NO2-LIF one main interferences NH2-LIF, its effects can be negligible on side, care only need taken air side T < 800 K, maximum interference ∼33 ppm observed. chemical kinetic models, uncertainty 20%, limits measurements. technique best suited investigate turbulence-chemistry interaction turbulent combined scattering, it provide useful validation data numerical when used.