Characterization of multi-jet turbulent flames in cross flow using stereo-PIV and OH-PLIF

• The three dimensional velocity and OH fluorescence flow field are characterized in a situation representative of a flare.
• Lifted partially premixed and non-premixed turbulent flames are observed.
• Turbulent velocity fluctuations are not dampened through the partially premixed flame brush.
• Non-premixed flame merging is found to occur.

The aim of this work is to present an experimental characterization of the three-dimensional turbulent flow field of a methane multiple jet configuration, representative of a ground flare, when both flame liftoff and flame surface interactions occur. The multiple jets exhibit different inclination with respect to the air cross flow. This characterization is performed using combined stereo particle imaging velocimetry and OH planar laser induced florescence. The flow field structure is discussed based on these combined measurements in 14 planes by examining the average velocity components and OH fluorescence, as well as the turbulent kinetic energy and OH fluorescence variance. The fuel jets that exhibit a higher inclination with respect to the air flow are determined to mix prior to the flame brush. The resulting flame exhibits partially premixed flame characteristics, and turbulent velocity fluctuations are not dampened through the flame brush. The less inclined jets exhibit a turbulent non-premixed flame structure, albeit not in a strict classical sense, since flame merging is observed.