Effects of step height on low emission stirred swirl combustor

A single annular lean-burn internally-staged combustor consists of pilot stage and main stage. The pilot stage is located in the center-line of the combustion chamber while the main stage surrounds coaxially the pilot stage. There exists a physical isolation called step height between the two stages. The emission tests using a single module rectangular combustor were operated under the idle condition to study the effects of step height on NO_X. The commercial software Fluent was used to simulate the cold flow field and combustion performance. The results indicate that step height has a great influence on the emission of NO_X. When the step height increases by 38%, the surface and volume of primary center recirculation zone will increase by 6.7% and 16.4%. However, the axial length has a decrease of the small amount and the emission of EI_NOX will increase by 35.1%.