Impact of co- and counter-swirl on flow recirculation and liftoff of non-premixed oxy-flames above coaxial injectors

Controlling the flame shape and its liftoff height is one of main issues for oxy-flames to limit heat transfer solid components injector. An extensive experimental study carried out analyze effects co- counter-swirl on flow patterns non-premixed stabilized above a coaxial injector when both inner fuel annular oxidizer streams are swirled. A swirl level greater than 0.6 in stream shown yield compact with strong central recirculation zone that attached rim tube absence swirl. It weakens this leading more elongated flames, while co-swirl enhances it flames. These results obtained high levels contrast previous observations made gas turbine injectors operated at lower which mainly achieved counter-rotating swirlers. Imparting leads lifted flames due partial blockage outlet by causes strain rates wake rim. This influenced rotation direction. global number then introduced structure far from burner where dissipation takes place jets mix. model derived well reproduces evolution mass rate recirculating gases measured non-reacting conditions outer momentum flux ratio between two varied.