Study on the Non-Reacting Flowfield Characteristics of Lean Premixed Injector Modules With the Convergent Outlet

Abstract

To form lifting flame and prevent auto-ignition and flashback, this paper proposed an original lean premixed injector with a convergent outlet. The influence of key structures (swirler-vanes angles, swirler-vanes profiles and premixing section lengths) on flowfield characteristics of lean premixed injector was investigated by the combination of laser diagnostic experiments and numerical simulations. The results show that there is a stable and sizeable detached central recirculation zone (CTRZ) downstream of the all six injectors and the detached distance from the convergent outlet decreases with the increase of the swirl number (SN) of the injector. With the increase of the swirler-vanes angle or the premixing section length, the SN of the injector increases, resulting in the CTRZ closer to the convergent outlet. Compared with the straight swirler-vanes, the SN of the curved swirler-vanes with the same angle is smaller, and the size of the its CTRZ is smaller and more backward. In addition, The peak value of the reflux ratio, which is also an important parameter to measure the flowfield characteristics, increases with the increase of the SN of the injectors.