Helical vortex core dynamics and flame interaction in turbulent premixed swirl combustion: A combined experimental and large eddy simulation investigation

Soufien Taamallah, Y Dagan, N Chakroun, Santosh Shanbhogue, Konstantina Vogiatzaki, Ahmed F Ghoniem

Research output: Contribution to journalArticle

Abstract

In this study, a combined experimental and Large Eddy Simulation (LES) investigation is performed to identify the vortical structures, their dynamics, and interaction with a turbulent premixed flame in a swirl-stabilized combustor. Our non-reacting flow experiment shows the existence of large scale precessing motion, commonly observed for such flows. This off-axis precessing dynamics disappears with combustion but only above a critical equivalence ratio at which the flame attaches to the swirler center body and vortex breakdown changes from a cone to a bubble type. For compact flames stabilized along the inner shear layer (ISL), no precessing is seen, but large scale vortices along the ISL are observed; these structures interact with the ISL-stabilized flame and contribute to its wrinkling as revealed by laser-induced fluorescence data. After validating the LES results in terms of low order statistics and point temperature measurements in relevant areas of the flow, we show that it can capture the precessing motion in the non-reacting flow and its suppression with combustion. The simulations show that the ISL vortices in the reacting case originate from a vortex core that is formed at the swirler’s centerbody. This vortex core has a conical helical shape that interacts—as it winds out—with the ISL and the flame stabilized along it. The simulated helical vortex core (HVC) exists in both reacting and non-reacting flows; in the latter, it is dominated by the off-axis motion, whereas in the reacting case, that motion is damped and only remains the cork-screw type solid body rotation of the HVC.
Original languageEnglish
Article number025108
JournalPhysics of Fluids
Volume31
Issue number2
DOIs
Publication statusPublished - 5 Feb 2019

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Large eddy simulation
Vortex flow
Combustors
Temperature measurement
Cones
Fluorescence
Statistics
Lasers

Keywords

  • vortex dynamics
  • large eddy simulations
  • Combustion
  • gas turbines

Cite this

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title = "Helical vortex core dynamics and flame interaction in turbulent premixed swirl combustion: A combined experimental and large eddy simulation investigation",
abstract = "In this study, a combined experimental and Large Eddy Simulation (LES) investigation is performed to identify the vortical structures, their dynamics, and interaction with a turbulent premixed flame in a swirl-stabilized combustor. Our non-reacting flow experiment shows the existence of large scale precessing motion, commonly observed for such flows. This off-axis precessing dynamics disappears with combustion but only above a critical equivalence ratio at which the flame attaches to the swirler center body and vortex breakdown changes from a cone to a bubble type. For compact flames stabilized along the inner shear layer (ISL), no precessing is seen, but large scale vortices along the ISL are observed; these structures interact with the ISL-stabilized flame and contribute to its wrinkling as revealed by laser-induced fluorescence data. After validating the LES results in terms of low order statistics and point temperature measurements in relevant areas of the flow, we show that it can capture the precessing motion in the non-reacting flow and its suppression with combustion. The simulations show that the ISL vortices in the reacting case originate from a vortex core that is formed at the swirler’s centerbody. This vortex core has a conical helical shape that interacts—as it winds out—with the ISL and the flame stabilized along it. The simulated helical vortex core (HVC) exists in both reacting and non-reacting flows; in the latter, it is dominated by the off-axis motion, whereas in the reacting case, that motion is damped and only remains the cork-screw type solid body rotation of the HVC.",
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author = "Soufien Taamallah and Y Dagan and N Chakroun and Santosh Shanbhogue and Konstantina Vogiatzaki and Ghoniem, {Ahmed F}",
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Helical vortex core dynamics and flame interaction in turbulent premixed swirl combustion : A combined experimental and large eddy simulation investigation. / Taamallah, Soufien; Dagan, Y; Chakroun, N; Shanbhogue, Santosh; Vogiatzaki, Konstantina; Ghoniem, Ahmed F.

In: Physics of Fluids, Vol. 31, No. 2, 025108, 05.02.2019.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Helical vortex core dynamics and flame interaction in turbulent premixed swirl combustion

T2 - A combined experimental and large eddy simulation investigation

AU - Taamallah, Soufien

AU - Dagan, Y

AU - Chakroun, N

AU - Shanbhogue, Santosh

AU - Vogiatzaki, Konstantina

AU - Ghoniem, Ahmed F

PY - 2019/2/5

Y1 - 2019/2/5

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AB - In this study, a combined experimental and Large Eddy Simulation (LES) investigation is performed to identify the vortical structures, their dynamics, and interaction with a turbulent premixed flame in a swirl-stabilized combustor. Our non-reacting flow experiment shows the existence of large scale precessing motion, commonly observed for such flows. This off-axis precessing dynamics disappears with combustion but only above a critical equivalence ratio at which the flame attaches to the swirler center body and vortex breakdown changes from a cone to a bubble type. For compact flames stabilized along the inner shear layer (ISL), no precessing is seen, but large scale vortices along the ISL are observed; these structures interact with the ISL-stabilized flame and contribute to its wrinkling as revealed by laser-induced fluorescence data. After validating the LES results in terms of low order statistics and point temperature measurements in relevant areas of the flow, we show that it can capture the precessing motion in the non-reacting flow and its suppression with combustion. The simulations show that the ISL vortices in the reacting case originate from a vortex core that is formed at the swirler’s centerbody. This vortex core has a conical helical shape that interacts—as it winds out—with the ISL and the flame stabilized along it. The simulated helical vortex core (HVC) exists in both reacting and non-reacting flows; in the latter, it is dominated by the off-axis motion, whereas in the reacting case, that motion is damped and only remains the cork-screw type solid body rotation of the HVC.

KW - vortex dynamics

KW - large eddy simulations

KW - Combustion

KW - gas turbines

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JO - Physics of Fluids

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