58658 - Influence of Atomization Characteristics on Lean Blow-Out Limits in a Gas Turbine Combustor 

Lean blow-out (LBO) limits play a critical role in the operational envelope of aircraft. In this paper, the influence of atomization characteristics on the LBO limit in the gas turbine combustor is quantitatively studied in order to predict the LBO limit in aero-engine combustor more accurately. Atomization characteristics can be reflected in the initial mean droplet diameter (SMD), the droplet velocity and the spray cone angle, etc. Semiempirical correlations, a convenient and fast methodology to estimate the LBO limit for aircraft engine combustors, are extensively employed in the preliminary combustion design stage. However, in the Lefebvre model, which is widely used at present, the effect of atomization on the LBO limit is only reflected in the evaporation rate of droplet, that is, the initial SMD. In the experiment, several pressure swirl atomizers with different geometry sizes were used to obtain sprays with different atomization characteristics. The results show that the droplet velocity and the spray cone angle also have great influence on the LBO limit, so they cannot be ignored. As the initial SMD decreases, the LBO limit shifts toward lower equivalence ratios. As the droplet velocity increases, the LBO limit shifts toward higher equivalence ratios. When other characteristics remain unchanged, the smaller the spray cone angle, the smaller the LBO equivalence ratios. It is concluded that when the initial SMD, the droplet velocity and the spray cone angle are taken into consideration, the predicted LBO limit value shows better agreement than the Lefebvre model.