Spray characteristics of liquid fuel air-assisted atomizers developed for a lean premixed-prevaporization combustor were evaluated under two kinds of conditions: in still air under non-evaporation conditions at atmospheric pressure and in a prevaporization-premixing tube under evaporation conditions with a running gas turbine. The non-evaporated mass fraction of fuel spray was measured using a phase Doppler particle analyzer in the prevaporization-premixing tube, in which the inlet temperature ranged from 873K to 1173K. The evaporation of the fuel spray in the tube is mainly controlled by its atomization and distribution. The NOx emission characteristics measured with a combustor test rig were evaluated with three-dimensional numerical simulations. A low non-evaporated mass fraction of less than 10% was effective in reducing the exhausted NOx from lean premixed-prevaporization combustion to about 1/6 times smaller than that from lean diffusion (spray) combustion. The flow patterns in the combustor are established by a swirl chamber in fuel-air preparation tube, and affect the flame stabilization of lean combustion.

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