BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Talks.cam//talks.cam.ac.uk//
X-WR-CALNAME:Talks.cam
BEGIN:VEVENT
SUMMARY:The forced heat release response of stratified flames to acoustic 
 velocity fluctuations - Henry Han\, PhD student\, Hopkinson Lab
DTSTART:20131011T100000Z
DTEND:20131011T110000Z
UID:TALK47763@talks.cam.ac.uk
CONTACT:Simone Hochgreb
DESCRIPTION:Combustion instability has long been the primary obstacle to t
 he development and application of advanced GT engines. Flames under nonuni
 form stoichiometric conditions leave the combustion system more susceptibl
 e to the instability. The forced heat release responses of stratified lean
 -premixed flames to acoustic velocity fluctuations are investigated. A lab
 oratory-scale burner and its boundary conditions were designed to generate
  high-amplitude acoustic velocity fluctuations in flames subject to well-d
 efined radial equivalence ratio distributions created via a split annular 
 fuel delivery system with a swirling stabilizer. A quartz tube was used as
  a combustor to generate forced flames. Simultaneous measurements on the o
 scillations of inlet velocity and heat release rate were carried out. A hi
 gh speed CMOS camera was used to capture the chemiluminescence images. The
  measurements show that the flame responses vary significantly depending o
 n the parameters of forcing frequency\, equivalence ratio split and veloci
 ty fluctuation\, for a given mean global power. The modification of the fl
 ame structure by stratification changes the nonlinear response of flames t
 o both low and high-amplitude acoustic forcing. The gain of the flame tran
 sfer function is larger for the cases of inner flow enrichment under high 
 forcing frequencies. The results confirm previous findings that increasing
  stratification towards the inner zone increases the gain and susceptibili
 ty to instabilities. The reasons are still being investigated\, but involv
 e the interaction of the location of the centroid of heat release and the 
 speed of propagation of the perturbation of the velocity along the shear r
 egion near the stabilization point.
LOCATION:Hopkinson Meeting Room\, Engineering Department
END:VEVENT
END:VCALENDAR