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SUMMARY:Dynamic Processes in Fundamental and Applied Turbulent Combustion 
 - Adam M. Steinberg\, German Aerospace Centre (DLR) Institute of Combustio
 n Technology
DTSTART:20091002T093000Z
DTEND:20091002T103000Z
UID:TALK19903@talks.cam.ac.uk
CONTACT:15158
DESCRIPTION:Results will be discussed from investigations into dynamic tur
 bulent combustion phenomena using\nhigh‐speed planar laser diagnostics. 
 In the first investigation\, the processes of flame surface straining\nand
  wrinkling that occur as turbulence interacts with a premixed flame were s
 tudied using highspeed\nparticle image velocimetry. It was shown that the 
 standard method of characterizing\nturbulence‐flame interactions based o
 n vortical structures is insufficient to describe the strain‐rate\nexert
 ed on a flame\; coherent structures of fluid‐dynamic strain‐rate also 
 must be considered.\nFurthermore\, the geometry of the interaction signifi
 cantly affected the flame response\, precluding\nthe use of simplified con
 figurations to develop turbulent combustion simulation models. Based on\nt
 hese observations\, empirical relationships were developed for important t
 erms in such models.\nThese relationships showed distinct dependencies on 
 the scale and configuration of the turbulence.\nIn the second investigatio
 n\, high‐speed particle image velocimetry and OH planar laser induced\nf
 luorescence were used to study the dynamics of a gas‐turbine‐like conf
 ined swirl flame. Heat\nrelease fluctuations were found to occur at the ac
 oustic frequency\; however\, the flame was operated\nin a ‘quite’ mode
  in which these fluctuations did not couple to produce a thermo‐acoustic
 ally\nunstable system. The method of spatio‐temporal proper orthogonal d
 ecomposition was used to\ndetermine the dynamics of the dominant flow feat
 ures\, while important heat release metrics were\ndetermined by mapping th
 e flame topography from the OH PLIF images. It was found that the\ndominan
 t flow structure was a helical vortex core that precessed around the burne
 r nozzle at a\nfrequency that was independent from the combustor acoustics
 . However\, various metrics of the\nheat release\, some caused by turbulen
 ce‐flame interaction\, fluctuated at the acoustic frequency. By\nstudyin
 g the frequency and phase of these processes\, a coherent picture of the c
 ombustor dynamics\nwas developed.
LOCATION:Lecture Room 6  Engineering Department
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