Theoretical and numerical studies on the reaction flow field and combustion performance of two-stage axial swirler combustors were carried out. The effects of total swirl number and swirler rear (sleeve) geometric structure size on the reaction flow field and combustion performance were investigated numerically. Results showed that the swirling flow tended to break away from the sleeve throat wall

forming jet-like flow when the total swirl number was small. And the swirling flow intensity increased with the increasing sleeve divergence angle. Airflow divergence angle increased with the increasing sleeve divergence half angle in the range from 30° to 70°. It was found that there was a critical divergence half angle 73° of sleeve. When the angle was greater than the critical angle

the airflow broke away from the sleeve wall. In addition

an empirical formula for estimating the airflow divergence angle of sleeve exit was developed by theoretical method together with numerical simulation. Compared with experimental and numerical results

it is found that the formula can predict the flowfield development downstream the swirlers accurately

providing a practical and effective method for the design of multi-stage swirlers in the future.