Particle image velocimetry (PIV) was used to study the effect of atomizer shroud carbon deposit removing hole area on the outlet flow field of double-swirler. The result showed that

when the ratio of the carbon deposit removing hole area to the double-swirler area increased from 0 to 0.24

the recirculated air velocity decreased and less air was recirculated into the double-swirler. When the ratio of the carbon deposit removing hole area to the double-swirler area was more than 0.18

the carbon deposite removing air would destory the sysmmetrical double-vortex structure and disturb the outlet flow field

which with X/D=0-0.8 was critically influenced by the carbon deposit removing air.