Study Of The Flow Field Characteristics Of A Central Staged Combustor

In this paper,a numerical investigation is carried out to study the characteristics of the flow field in the centrally staged combustor.Through the numerical method based on the Reynolds averaged N-S equation,the effects of the main vane angle,the expansion angle of the pilot’s sleeve,and the lip height on the flow characteristics of the centrally staged combustor were studied.Through the numerical method based on large eddy simulation,the dynamic flow field characteristics and flow field formation mechanism of the centrally staged combustor were studied.The main conclusions of this paper are as follows:(1)Under the coupling effect of the main vane angle and the contractive combustor outlet,there is a low-pressure area downstream of the flow field,which has a significant effect on the pilot airflow.The main vane angle increases while the pilot airflow opening angle decreases.(3)The lip height affects the coupling effect between the main and the pilot airflow.When the lip height is short,the main airflow and the pilot airflow merge quickly.When the lip height increases to a certain extent,a part of the pilot airflow is merged with the main airflow,and the other part flows to the outlet of the combustor under the influence of the downstream low-pressure area.(4)A large-eddy simulation study on the flow field characteristic of a simplified central staged combustor shows that there are theoretically five flow field structures in the centrally staged combustor,including "circinal primary recirculation zones," "U-shaped primary recirculation zones," and "dual primary recirculation zones," which have been captured in the model combustor.(5)There are intense shearing and countering effects between the axial airflow and the recirculated airflow upstream of the flow field,forming a chain of vortex structures.The pilot airflow is very unstable with its flow direction varying with time rapidly.The lowpressure area near the contractive outlet of the combustor is mainly due to the accelerating effect and the swirl effect of the airflow.The lower the pressure is in the low-pressure area,the more significant the impact on the upstream pilot airflow.