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UID:event-33@tuemeche.nl
DTSTAMP:20261007T234654Z
DTSTART;TZID=Europe/Amsterdam:20270113T160000
DTEND;TZID=Europe/Amsterdam:20270113T173000
SUMMARY:The turbulent premixed bluff body stabilized ammonia/hydrogen/nit
 rogen/air flame - A fundamental study for gas turbine combustor regarding
  extinction and molecular transport effects under different NH₃/H₂ ra
 tios
DESCRIPTION:Speaker: Boyan Xu\nHost: Rob Bastiaans\n\nThe gas turbine is 
 a promising energy supply solution for AI data centers\, attributed to it
 s advantages regarding stable\, high-power capacity\, and fast startup. T
 o get rid of the dependence on fossil fuel and mitigate the emission\, re
 newable fuels produced by redundant green electricity\, such as ammonia a
 nd hydrogen\, become candidates of gas turbine fuel options to replace na
 tural gas and other fossil fuels. Partially cracked ammonia has the advan
 tages of both ammonia and hydrogen\; thus\, it is regarded as a potential
  fuel to be used in gas turbines. To mimic the flame within the flow fiel
 d in practical gas turbine combustors\, a bluff-body-stabilized flame is 
 selected as the configuration to study the stretch flame behavior in the 
 recirculation zone. Blow-off (extinction) is one of the most important ch
 allenges within the combustor\, especially the near blow-off conditions a
 re required for controlling emissions. Figuring out the principle of the 
 bluff-body stabilized partially cracked ammonia flame blow-off is the mai
 n purpose of this study.\nStarting from the most simplified flame extinct
 ion process\, a one-dimensional twin counterflow premixed flame is first 
 studied to exclude the influence of turbulence\, three-dimensional flow f
 ield\, and flame surface wrinkling. By increasing the strain rate\, the f
 lame is first enhanced when pushing towards. The final extinction is caus
 ed by incomplete combustion when reactants have not enough space and time
  to react. With a fixed equivalence ratio\, a non-monotonic change of the
  dimensionless extinction strain rate with ammonia cracking ratio is foun
 d. By isolating the preferential diffusion effect and non-unity Lewis num
 ber effect\, the preferential diffusion effect has proved to be the reaso
 n for the non-monotonic change.\nTo accurately predict the blow-off of th
 e bluff-body-stabilized partially cracked ammonia flame\, a numerical met
 hod with Large Eddy Simulation\, detailed chemistry\, and a conjugate hea
 t transfer model is established. The simulation result is validated by ex
 periment regarding the flow field and flame distribution. With the valida
 ted numerical method\, the extinction of two ammonia/hydrogen flames is p
 redicted within the experimental error bar\, and the blow-off processes a
 re analyzed. For the 70% NH₃ flame\, the continuous shear layer flame s
 urface prevents the thermal convection between the hot burnt gas inside t
 he recirculation zone and the cold unburnt. The blow-off of the 70% NH₃
  flame starts from the local extinction along the shear layer flame and c
 auses the shear layer flame breakup. With the breakup\, the mixing at the
  shear layer dominated by turbulent vortices cools down the recirculation
  zone and makes the flame kernels not sustainable\, and the flame finally
  extinguishes. In comparison\, the 40% NH₃ flame is more fragmented tha
 n the 70% NH₃ flame during the stable stage. Due to the absence of the 
 continuous shear layer flame surface\, the blow-off bulk velocity of it i
 s lower than the expected value\, which is based on the one-dimensional e
 xtinction strain rate ratio of these two flames.\n\nMore info: https://ww
 w.tue.nl/en/research/researchers/boyan-xu/
LOCATION:Atlas 0.710
URL:https://tuemeche.nl/peoplepages/event.php?id=33
CATEGORIES:PhD Defense
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