Numerical Study on Adjustable Range of Secondary Air Swirl Intensity

Numerical simulation was conducted with software Ansys 12.0 on the flow field of power plant boiler, so as to study the effect of swirl intensity of both the internal and external secondary air on the in-furnace flow field. Results show that with the rise of swirl intensity, the central backflow zone begins to move away from the axis of burner outlet, with an elongated length and an enlarged area; when the swirl intensity rises to a certain value, no ideal central backflow zone would be formed, in which case flash phenomenon may occur; the swirl intensity of external secondary air has a higher effect on the backflow zone, with an adjustable range narrower than that of the internal secondary air; the adjustable range of internal and external secondary air is 0.58-2.74 and 0.58-1.00 respectively.