Flow characteristics of the confined combustion flames of counter dual-stage swirler were analyzed. Research found that

the flow characteristics of the counter dual-stage swirler changed with the confinement ratio variation. When the confinement ratio was less than 3.8

the center backflow bubble on this flow field grew longer as the confinement ratio increased

with the growth law the same as that of the center backflow bubble on the single-stage swirler flow field. However

as the confinement ratio continued to increase

the growth law of the center backflow bubble was different between the counter dual-stage swirler and the single-stage swirler. The center backflow bubble on the single-stage swirler flow field continued to grow longer

while the center backflow bubble on the counter dual-stage swirler flow field was split into two different backflow bubbles. This result has deepened the understanding of the effect of confinement on flow and combustion

and provided a guidance for the optimal design of the counter dual-stage swirler.