A Numerical Study on NOX Emission of Swirl Premix Burner Affected by Air Fuel Ratio and Air Slit Area in a Model Gas Turbine Combustor

Two factors that affect NOX emission of swirl premix burner are investigated numerically in the present study. The first one is air fuel ratio which is changed from 31.7 to 38.7 by keeping the air flow rate and decreasing the fuel flow rate. As the air fuel ratio increases, the mixing is enhanced and temperature of a model combustor decreases. Then, the NOX emission decreases. The second factor is the air slit area of the burner. Air slit area is reduced by changing the width of slit with 3 methods depending on the position, i.e., width decrease in the upper-side, the lower-side, and both sides. The velocity of air inflow increases as the air slit width decreases. Then, unmixedness inside the burner will be reduced, which results in reduction of NOX emission. This strong correlation between unmixedness and NOX emission verifies that NOX reduction can be attained by mixing enhancement of fuel and air inside the burner.