Effect of Inner/Outer Secondary Air Mass Flow Rate on the Airflow Characteristics of the 14-MW Double Cone Burner

The double cone burner is the only coal-fired burner in China that utilizes a annular reverse structure and has been industrialized. Cold airflow experiments on a 1:2 scaled model burner was preformed. Testo 425-hot wire anemometer was used to measure the cold aerodynamic characteristics of the double cone burner. Results show that with increasing the inner secondary air ratio, the length of the recirculation zone has not changed; The width of the recirculation zone does not change substantially without the cone, but it tends to generally increase with increaseing of the inner secondary air ratio with the cone; The shape of the recirculation zone is always a ring structure. When the cone is added, the axial dimensionless mean velocity becomes larger than that without the cone, but the jet profile becomes smaller. In both cases with and without the cone, the axial dimensionless mean velocity near the center of the burner is negative due to the reverse injection of the primary air into the cone.