Reduction of NOx emission of aircraft gas turbines is moving in the direction of development of direct combustor fuel injection systems providing conditions for rapid mixing and combustion of a uniform lean fuel/air mixture. However, formation of sufficient uniform fuel/air mixture in real combustors fails to be completed. It may result in burning out a considerable portion of fuel in stoichiometric conditions that in turn imposes limits on the emission level minimizing. The research accomplished by a number of authors justifies the necessity of decreasing the extent of stoichiometric zones by means of increasing fuel-air mixing rate on the stoichiometric surface of their contact, to reduce emission. This publication contains the analysis results upon the effect of mixing rate, in terms of a methane-air laminar diffusion combustion. It is proved that changes of mixing rate influence the two main factors governing the emission level: the extent of NO production zone and the efficient rate of its production. If the mixing rate increases explicitly due to the decrease of NOx production scale, the efficient velocity curve will contain a maximum value. Furthermore, the scale effect is all-over stronger than the kinetic one. It is concluded that in case of mixing rate increase, the reduction of NOx emission goes nonlinearly and steadily. The ranges of maximum effect are specified. Herewith, we introduce the relation, which demonstrates that in the diffusion combustion a sufficient reduction of NOx emission can be achieved.
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