Swirling Flows in an Axisymmetric Lean Premixed Combustor

Umeh, Chukwueloka O. U.; Rusak, Zvi

doi:10.2514/6.2006-3732

Cited by 5 publications

(3 citation statements)

References 17 publications

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“…The effects of mesh refinement on the solution were investigated [26,28] using three uniform meshes consisting of 15,238 cells, 26,308 cells, and 40,198 cells. Each case was run until the solution reached a near-time-asymptotic behavior along the inlet section and in front of the breakdown zone, i.e., until there was a change less than 0:01 m=s in the axial velocity upstream of a selected axial location downstream of the dump plane.…”

Section: A Numerical Schemementioning

confidence: 99%

Experimental and Computational Study of Nonreacting Vortex Breakdown in a Swirl-Stabilized Combustor

et al. 2010

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Nonreacting flow experiments are conducted in a swirl-stabilized combustor with several configurations of a triple annular research swirler fuel injector. Particle imaging velocimetry is used to measure mean axial, radial, and tangential distribution of the velocity field, from which the swirl ratio and the position of vortex breakdown are calculated for each injector configuration. Numerical simulations based on the Reynolds-averaged Navier-Stokes model equations of nonreacting flows provide insight into the characteristics of the axisymmetric vortex breakdown phenomenon in a circular, finite-length pipe with a sudden expansion downstream of a concentric, circular inlet pipe. Results show that flow states with vortex breakdown can be simulated numerically. Good agreement is found between the results of the simulations and available theoretical predictions for the first appearance of breakdown downstream of the pipe expansion plane, as well as its first appearance in the inlet pipe section as the inlet swirl level is increased. Good agreement is also shown between the measured experimental data, simulations, and theoretical predictions. It is demonstrated that the theoretical criteria and numerical simulations can be used to predict the appearance and location of vortex breakdown for several different nozzles of varying swirl numbers relevant to the stability of lean, premixed combustion.

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Section: A Numerical Schemementioning

confidence: 99%

Experimental and Computational Study of Nonreacting Vortex Breakdown in a Swirl-Stabilized Combustor

et al. 2010

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“…Umeh et al [18] modeled an axi-symmetric lean premixed combustor to study the phenomena of swirling flows and vortex breakdowns. Realizable k − model was used for capturing the turbulence.…”

Section: Rans Models For Turbulencementioning

confidence: 99%

Effects of Swirl Number and Central Rod on Flow in Lean Premixed Swirl Combustor

Yellugari

Gomez

Gutmark

2020

AIAA Scitech 2020 Forum

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Gas turbine combustors are used to extract chemical energy from the combustion of fuel in presence of an oxidizer to power turbines. Environmental concerns provide motivation to develop more efficient and less polluting gas turbine engines. To achieve good emission performance, lean burn combustors with low pollutant emissions have been developed. These combustors operate at fuel lean conditions and they can be classified into lean premixed and pre-vaporized (LPP) combustor, where the fuel and oxidizer are premixed and pre-vaporized to form a homogeneous mixture in a dedicated region, premixer, just before the fuel-oxidizer mixture enters the combustion chamber, and lean direct injection (LDI) combustor, where the fuel is directly injected into the flame zone without any premixing with oxidizer [1]. The premixing and pre-vaporizing reduce the residence time, the amount of time the gases are in the combustion chamber. The reduction in residence time reduces the NO x emissions, as the high NO x emissions are produced with a long residence time in the combustion chamber. The flow behavior of non-reacting and reacting flow in a lean premixed swirl combustor, adapted from KAUST experimental rig, has been studied using RANS in the commercial software, Ansys-Fluent. Turbulence is modeled using the two equation realizable k − model and the turbulence-chemistry interaction is modeled by a flamelet generated manifold (FGM) technique. At first, non-reacting flow was simulated in lean premixed swirl combustor. These simulation results were compared to the experiments done by Sabatino et al. [2] and LES work of Maestro et al. [3]. This non-reacting flow solution was used as an initial condition to the reacting flow for a faster convergence of the solution, with methane-air mixture at an equivalence ratio of 0.67. GRI 3.0 mechanism was used for modeling chemistry, which had 325 i chemical equations and 53 species to solve. The reacting flow results were compared with the experiments of Palies et al. [4]. Analyses are conducted to study the effect of swirl number and a cylindrical rod on the non-reacting and reacting flows. Higher axial velocities are observed in reacting flow, when compared to the nonreacting flow, because of the thermal expansion of the gases. Flow reattachment point to the combustion chamber wall after the expansion was moved upstream at high swirl numbers. A central toroidal recirculation zone (CTRZ) was observed from a swirl number, S = 0.52 in the case with a central rod, and from S = 0.54 in the case without a central rod and it helped to stabilize the flame. At low swirl numbers, the central rod, which was in the injection tube, helped the flow and flame to stabilize on top of it. In the absence of this central rod, the flame is lifted off and stabilized at a distance from the burner exit. Also, the flame length was shortened at high swirl numbers. As the swirl number was increased, the CTRZ started to move upstream. This phenomenon with flame flashback was observed from S = 0.7. A very high turbulence ...

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“…Baej et al[17] used shear-stress transport (SST) for modeling turbulence. Different nozzles with different swirl numbers were analyzed.Umeh et al[18] modeled an axi-symmetric lean premixed combustor to study the phenomena of swirling flows and vortex breakdowns. Realizable k − model was used for capturing the turbulence.…”

mentioning

confidence: 99%

Effects of Swirl Number and Central Rod on Flow in a Lean Premixed Swirl Combustor

Yellugari,

Villalva Gomez,

Gutmark

2023

Combustion Science and Technology

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Gas turbine combustors are used to extract chemical energy from the combustion of fuel in presence of an oxidizer to power turbines. Environmental concerns provide motivation to develop more efficient and less polluting gas turbine engines. To achieve good emission performance, lean burn combustors with low pollutant emissions have been developed. These combustors operate at fuel lean conditions and they can be classified into lean premixed and pre-vaporized (LPP) combustor, where the fuel and oxidizer are premixed and pre-vaporized to form a homogeneous mixture in a dedicated region, premixer, just before the fuel-oxidizer mixture enters the combustion chamber, and lean direct injection (LDI) combustor, where the fuel is directly injected into the flame zone without any premixing with oxidizer [1]. The premixing and pre-vaporizing reduce the residence time, the amount of time the gases are in the combustion chamber. The reduction in residence time reduces the NO x emissions, as the high NO x emissions are produced with a long residence time in the combustion chamber.The flow behavior of non-reacting and reacting flow in a lean premixed swirl combustor, adapted from KAUST experimental rig, has been studied using RANS in the commercial software, Ansys -Fluent. Turbulence is modeled using the two equation realizable k − model and the turbulence -chemistry interaction is modeled by a flamelet generated manifold (FGM) technique. At first, non-reacting flow was simulated in lean premixed swirl combustor. These simulation results were compared to the experiments done by Sabatino et al. [2] and LES work of Maestro et al. [3]. This non-reacting flow solution was used as an initial condition to the reacting flow for a faster convergence of the solution, with methane-air mixture at an equivalence ratio of 0.67. GRI 3.0 mechanism was used for modeling chemistry, which had 325 i I specially thank Dr. Urmila Ghia, for supporting me all the time. I would like to thank Ohio Supercomputer Center for letting me use the resources.I would like to thank my friends and people from work, for being patient, cooperative and supportive all these years in Cincinnati. All this could not be possible without my parents and my older brother. I so grateful to my parents and my brother for always believing in me.Their unconditional love and support always made me to dream big and achieve my dreams with ease. Finally, I am so thankful to my Master and Sir for their continuous blessings and guidance throughout my life . v

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Swirling Flows in an Axisymmetric Lean Premixed Combustor

Cited by 5 publications

References 17 publications

Experimental and Computational Study of Nonreacting Vortex Breakdown in a Swirl-Stabilized Combustor

Experimental and Computational Study of Nonreacting Vortex Breakdown in a Swirl-Stabilized Combustor

Effects of Swirl Number and Central Rod on Flow in Lean Premixed Swirl Combustor

Effects of Swirl Number and Central Rod on Flow in a Lean Premixed Swirl Combustor

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