Abstract:

In order to study the interstage cyclonic interference problem in micro-mixed diffusion combustion, in this investigation, particle image velocimetry (PIV) experiments and OH* fluorescence imaging experiments were used to verify the computational fluid dynamics (CFD) model. Subsequent simulations of the burner's combustion process at various flow velocities were conducted with Fluent. The calculation results comprehensively analyzed the interference phenomenon between the swirl flame and the flow field. It was observed that significant interference exists between the pilot stage jet and the main stage jet. The increase in flow velocity from 30 m/s to 60 m/s led to an advancement of the interference onset position in the hot state flow by 7.8%, in the cold state flow by 5.2%, and a delay in the interference onset position in the flame by 20.3%. Additionally, the flame height was noted to increase with the flow velocity, and the interference was found to expand the flame angle and the neck width of the central recirculation zone. Furthermore, the increase in flow velocity was identified to substantially impact the mixing effect within the interference zone, particularly deteriorating the mixing uniformity of the pilot stage. Research shows that flame interference and flow interference affect each other and will lead to an increase in NOx emissions.

Key words: Flow velocity, dual-swirl, flame/flow interference; micro-mixed combustion