Experimental and computational study of a lifted, non-premixed turbulent free jet flame

Mahmud, Tariq; Sangha, S. K.; Costa, Mário; Santos, Ana Isabel

doi:10.1016/j.fuel.2006.08.030

Cited by 23 publications

(11 citation statements)

References 65 publications

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“…However, the gradient on the co-flow side remains very sharp while shifted radially outwards with the peak temperature. This means that the mixing near the co-flow is not as effective as the fuel side so that the composition remains very lean, as also reported by Becker and Yamazaki [50] and Mahmud et al [51]. The temperature profiles at locations between z / D = 10 -25 (Figure 5c) show that the temperature remains constant in the core region of the fuel jet and increases sharply in the shear layer till the peak value is reached.…”

Section: Temperature Fieldsupporting

confidence: 71%

Stability Characteristics of a Turbulent Nonpremixed Conical Bluff Body Flame

Ata¹,

Özdemir²

2021

IJHT

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The thermal characteristics of turbulent non-premixed methane flames were investigated by four burner heads with the same exit diameter but different heights. The fuel flow rate was kept constant with an exit velocity of 15 m/s, while the co-flow air speed was increased from 0 to 7.6 m/s. The radial profiles of the temperature and flame visualizations were obtained to investigate the stability limits. The results evidenced that the air co-flow and the cone angle have essential roles in the stabilization of the flame: An increase in the cone angle and/or the co-flow speed deteriorated the stability of the flame, which eventually tended to blow off. As the cone angle was reduced, the flame was attached to the bluff body. However, when the cone angle is very small, it has no effect on stability. The mixing and entrainment processes were described by the statistical moments of the temperature fluctuations. It appears that the rise in temperature coincides with the intensified mixing, and it becomes constant in the entrainment region.

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Section: Temperature Fieldsupporting

confidence: 71%

Stability Characteristics of a Turbulent Nonpremixed Conical Bluff Body Flame

Ata¹,

Özdemir²

2021

IJHT

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“…Roomina and Bilger [11] reported a first-order CMC study of a CH 4 /air jet flame with reasonable accuracy for NO prediction. Mahmud et al [12] reported an experimental and computational study of a CH 4 jet flame. Their calculation by using a mixedness-reactedness flamelet model showed large overprediction of NO in the fuel-rich zone.…”

Section: Introductionmentioning

confidence: 99%

Laminar flamelet model prediction of NO_x formation in a turbulent bluff-body combustor

Ravikanti

Hossain

Malalasekera

2008

Proceedings of the Institution of Mechanical Engineers, Part A:

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A bluff-body combustor, with recirculation zone and simple boundary conditions, is ideal as a compromise for an industrial combustor for validating combustion models. This combustor, however, has proved to be very challenging to the combustion modellers in a number of previous studies. In the present study, an improved prediction has been reported through better representation of turbulence effect by Reynolds stress transport model and extended upstream computational domain. Thermo-chemical properties of the flame have been represented by a laminar flamelet model. A comparison among reduced chemical kinetic mechanism of Peters and detailed mechanisms of GRI 2.11, GRI 3.0, and San Diego has been studied under the laminar flamelet modelling framework. Computed results have been compared against the well-known experimental data of Sydney University bluff-body CH 4 /H 2 flame. Results show that the laminar flamelet model yields very good agreement with measurements for temperature and major species with all the reaction mechanisms. The GRI 2.11 performs better than the other reaction mechanisms in predicting minor species such as OH and pollutant NO. The agreement achieved for NO is particularly encouraging considering the simplified modelling formulation utilized for the kinetically controlled NO formation.

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“…Therefore, the experimental data at this nearest location to the nozzle exit are used as the inlet boundary conditions. The experimental data for the turbulence kinetic energy (k) at x/D e ¼ 0.5 are used as the inlet boundary condition for k. The dissipation rate of the turbulence kinetic energy (") at the inlet is calculated by " ¼ C 3=4 k 3=2 =l, where C is a constant (¼0.09), k is the turbulence kinetic energy, and l is the turbulence length scale which can be approximated as 0.33D e (Mahmud et al, 2007). The computational domain is chosen to be long enough to ensure complete development of the flow; that is, up to x/D e ¼ 120.…”

Section: Turbulence Closure Modelsmentioning

confidence: 99%

Three‐dimensional numerical simulation of an equilateral triangular turbulent free jet

Shamami

Birouk

2009

Int Jnl of Num Meth for HFF

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Purpose -This paper aims to describe the numerical simulation of a three-dimensional turbulent free jet issuing from a sharp-edged equilateral triangular orifice into still air. Design/Methodology/approach -The numerical simulation was carried out by solving the governing three-dimensional Reynolds-averaged Navier-Stokes equations. Several two-equation eddyviscosity models (i.e. the standard k-", renormalization group (RNG) k-", realizable k-", shear-stress transport (SST) k-!), as well as the Reynolds stress models (i.e. the standard RSM and the SSG) were tested to simulate the flowfield. The numerical predictions were compared with experimental data in order to assess the capability and limitations of the various turbulent models examined in this work. Findings -The vena contracta effect was predicted by all the tested models. Among the eddyviscosity models only the realizable k-" model showed good agreement of the near-field jet decay. None of the eddy-viscosity models was capable of predicting the profiles of the jet turbulence intensities. The RSMs, especially the standard RSM, were able to produce much better predictions of the features of the jet in comparison with the eddy-viscosity models. The standard RSM predictions were found to agree reasonably well with the experimental data.Research limitations/implications -The conclusion, that among the tested RANS turbulence closure models, the RSM appeared the only one capable of reproducing reasonably well the experimental data concerns only the jet flow case examined here. Also, the average computational time for a single run was quite long, i.e. 340 h, but it is believed that parallel computing will reduce it considerably. Originality/value -The numerical results reported in this paper provide a comparison between several RANS turbulence closure models for simulating a turbulent free jet issuing from an equilateral triangular nozzle.

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Experimental and computational study of a lifted, non-premixed turbulent free jet flame

Cited by 23 publications

References 65 publications

Stability Characteristics of a Turbulent Nonpremixed Conical Bluff Body Flame

Stability Characteristics of a Turbulent Nonpremixed Conical Bluff Body Flame

Laminar flamelet model prediction of NO_x formation in a turbulent bluff-body combustor

Three‐dimensional numerical simulation of an equilateral triangular turbulent free jet

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Experimental and computational study of a lifted, non-premixed turbulent free jet flame

Cited by 23 publications

References 65 publications

Stability Characteristics of a Turbulent Nonpremixed Conical Bluff Body Flame

Stability Characteristics of a Turbulent Nonpremixed Conical Bluff Body Flame

Laminar flamelet model prediction of NOx formation in a turbulent bluff-body combustor

Three‐dimensional numerical simulation of an equilateral triangular turbulent free jet

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Laminar flamelet model prediction of NO_x formation in a turbulent bluff-body combustor