LASER DIAGNOSTICS TO IDENTIFY LOCATIONS WHERE NITRIC OXIDE IS PRODUCED WITHIN FLAMES

New laser diagnostics are proposed that make it possible to identify the locations within flames where the rate of production of nitric oxides, d[NO]/dt, is especially large. The method is based on measuring the terms on the right-hand side of the rate equation for thermal NO: The proposed method combines laser-induced fluorescence (LIF) to measure the oxygen atom concentration [O], laser Rayleigh scattering to quantify gas temperature, and an equilibrium assumption to determine [N 2 ] from the temperature data. Previously, it has been possible to measure concentrations of NO with LIF, but this is not sufficient; what also is needed is a way to measure the rate of production of nitric oxides (d[NO]/dt) to identify locations where production of NO is excessive. The accuracy of the proposed LIF/Rayleigh scattering method was investigated by comparing results to those obtained with conventional sampling probes and equilibrium chemistry codes. Signal to noise and accuracy are discussed.