The Design and Characteristics of a Novel Injector: A Lobed Swirl Injector

The design procedure of a novel injector — a lobed swirl injector is presented. The lobed swirl injector can play an effective role in swirl generation and enhancing the mixing. Besides, by adjusting the axial position of the lobed swirler, non-premixed combustion can evolve into premixed combustion, and vice versa. It was tested in a low swirl burner configuration. Four perforated plates with different blockage ratios are used to bypass the inlet flow and adjust the turbulent intensity. Velocity distributions at the exit of the burner are captured with two-dimensional Particle Image Velocimetry. The fuel is methane and flames are visualized by camera. The experiments results indicate that the operation range is broadened by the lobed swirler. Compared with flame of vane swirler, flame of lobed swirler is more stable. With the lobed swirler, the blow off occurred gradually and smoothly rather than violently as with the vane swirler. With an increase of air flow, the flame volume of the lobed swirler shrinks significantly, and the leading flame front position moves downstream which means the lift-off height increases. The change in the blowoff behavior for flames can be attributed to the complicated vortices downstream of the lobed swirler as these act to increase turbulence intensity and turbulent flame speed, which in turn influences blowoff limits.