To refine the design criteria of coaxial-staged swirlers

this study investigates the effects of the blade angles of the first and second main stages on flow field characteristics and combustion performance through numerical simulations

focusing on a low-emission tower-type coaxial-staged combustor fueled with natural gas. The coupling relationship between the two main stages on combustion performance is revealed. The results show that the angle of the second main stage blades has a significant impact on the flow field structure and combustion performance. When the angle of the second main stage blades is 30°

an effective recirculation zone fails to be formed in the non-reactive flow field. Within the range of blade angles considered in the study

increasing the angle of either the first main stage or second main stage blades can promote the mixing of fuel and air and shorten the flame length

thereby improving combustion efficiency and reducing pollutant formation. The angle of the second main stage blades is the main influencing factor. Considering various combustion performance parameters comprehensively

when both the first and second main stage blade angles are set to 55°

the combustor exhibits optimal overall performance. The study shows that a proper matching of the first and second main stage blade angles can significantly improve the flow and combustion performance of the coaxial-staged combustor.