Effect of Fuel Stage Proportion on Flame Position in an Internally-Staged Combustor

Abstract

To study the effect of fuel stage proportion on flame position and combustion characteristics of the internally-staged combustor, a detailed numerical investigation is performed in the present paper. The prediction method of flame position is established by analyzing the variations of the distribution of intermediate components and the turbulent flame speed. Meanwhile, the flame position is simulated to verify the accuracy of the prediction method. It is demonstrated that the flame position prediction model established in this paper can accurately predict the flame position under different fuel stage proportions. On this basis, special attention is paid to analyze the variation of velocity field, temperature field, distribution of intermediate components and emissions under different fuel stage proportions. As the proportion of pilot fuel stage increases slightly, the mass fraction of fuel at the combustor dome increases. In addition, the combustion characteristics change significantly with the increase in the proportion of pilot stage fuels. The flame moves downstream and the high temperature area increases as the proportion of pilot fuel increases. In particular, when the proportion of pilot stage reaches 3%, the highest flame temperature is generated due to the most concentrated reaction area, resulting in the largest emission of NOx. At the same time, due to the most complete reaction, the minimum CO emission is produced. When the proportion of pilot fuel stage reaches 1%, the NOx emission is the lowest, and the highest CO emission is generated due to the incomplete reaction.