L , 79 - 1 321 The Effect of Fuel Sprays on Emissions from a Gas Turbine

1n this program,aresearchgasturbinecombustor is used to study the influence of individual variables (in particular, fuel spray characteristics) on primary zone emissions. The unique combustor is operated under realistic conditions and allows for independent control of drop size, fuel-air ratio, air inlet temperature, pressure, reference velocity, and residence time. Also, it lends itself to theoretical modelling and to turbulence intensity measurements through use of laser velocimetry. A uniform spray is created by the air-blast atomization of fuel injected through 37 needles. Unidirectional gas flow is obtained (with no large scale recirculation) which allows for straightfoward determination of residence time and unambiguous interpretation of emissions results. Measurements of the following are presented: local concentrations of N k , CO and unburned hydrocarbons at various locations within the flow, local gas temperature, gas velocity and the turbulence intensity. Validity of the emissions data is tested using a comprehensive data analysis program to calculate the local fuel-air ratio and the sum of the m l e fractions of the species present. Results indicate that increasing the drop size, keeping residence time and all other parameters fixed, causes an increase in unburned hydrocarbons. Some unexpected trends in NOX levels are discussed. Increasing the residence time, keeping drop size and Other parameters fixed, results in sharp decreases in hydrocarbons and CO, and an increase in NOX.