Vortical and turbulent structure of a lobed mixer free shear layer

Mixing processes in a coaxial geometry with a central lobed mixer-nozzle

“…x/D = 3 where they are beginning to break down. Assuming a similar process is happening for N l, the vortex break down is probably initiated by the pinch off effect of McCormick [1992], but the flow visualizations of this study cannot confirm this because the visualization methods are different. McCormick seeded the boundary layer in his experiments whereas the whole inner flow was seeded for the present study, and thus detailed flow structures near the interface are not highlighted.…”

“…A very detailed and systematic study by McCormick [1992] revealed several more details of the flow patterns downstream of a lobed mixer. Extensive flow visualizations for laminar and turbulent air flow, and three-dimensional hot wire velocity measurements, showed that the Kelvin-Helmholtz vortices, which are normal to the flow direction, play a major role in the mixing process.…”

“…Another interesting observation by McCormick is that the scale of the normal vortices shed from the lobed mixer is about 1/4 that shed for a planar baseline case. Thus, it seems that the lobed mixer introduces smaller scales 29 into a flow sooner, which could enhance molecular mixing [McCormick andBennett, 1993, 1994]. studied axisymmetric lobed mixers used in ejector applications.…”

Experimental investigation of flow behavior for scalloped and lobed mixers

“…McCormick and colleagues 7,8 performed extensive flow visualizations and quantitative hot-film anemometry measurements on a forced mixer. Through smoke flow visualizations, the presumed existence of horseshoe-shaped vortices found in the lobe troughs at the mixer trailing edge were verified.…”

The Effects of Spoilers on Jet Mixing of Lobed Nozzles

“…Investigations concluded that the increase in the interfacial area between the primary and secondary streams (Elliott et al 1992) -at the same time forming inviscid streamwise vortices at the wake (Povinelli and Anderson 1984) -and the streamwise vortices interacting with the normal vortices ring which are formed at the interface of the streams for the gradient of the axial velocity (McCormick and Bennett 1994), are the dominating factors for high mixing effectiveness. The lobed nozzles have been widely used in the engineering applications (Presz et al 1994;Acheson et al 2011).…”