A comparison between the stabilization of premixed swirling CO 2 -diluted methane oxy-flames and methane/air flames

Jourdaine, Paul; Mirat, Clément; Caudal, Jean; Lo, A.; Schuller, Thierry

doi:10.1016/j.fuel.2016.11.017

Cited by 41 publications

(32 citation statements)

References 32 publications

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“…These previous investigations show that measuring the swirl number is a difficult task due to the contributions from pressure and turbulent fluctuations. For a flow in a duct with a smooth cross section area change over a short distance with respect to the duct rules when switching from air-to oxy-combustion operating mode with the same injector [17,22]. Only the main elements of the test rig are briefly described below.…”

Section: Methodsmentioning

confidence: 99%

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Effects of a Diverging Cup on Swirl Number, Flow Pattern, and Topology of Premixed Flames

Degenève

Jourdaine

Mirat

et al. 2018

Journal of Engineering for Gas Turbines and Power

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Impact of the diverging cup angle of a swirling injector on the flow pattern and stabilization of technically premixed flames is investigated both theoretically and experimentally with the help of OH* chemiluminescence, OH laser-induced fluorescence and particle image velocimetry (PIV) measurements. Recirculation enhancement with a lower position of the internal recirculation zone (IRZ) and a flame leading edge protruding further upstream in the swirled flow are observed as the injector nozzle cup angle is increased. A theoretical analysis is carried out to examine whether this could be explained by changes of the swirl level as the diffuser cup angle is varied. It is shown that pressure effects need in this case to be taken into account in the swirl number definition and expressions for changes of the swirl level through a diffuser are derived. It is demonstrated that changes of the swirl level including or not the pressure contribution to the axial momentum flux are not at the origin of the changes observed of the flow and flame patterns in the experiments. The swirl number without the pressure term, designated as pressure-less swirl, is then determined experimentally with laser Doppler velocimetry (LDV) measurements at the injector outlet for a set of diffusers with increasing quarl angles under nonreacting conditions and the values found corroborate the predictions. It is finally shown that the decline of axial velocity and the rise of adverse axial pressure gradient, both due to the cross section area change through the diffuser cup, are the dominant effects that control the leading edge position of the IRZ of the swirled flow. This is used to develop a model for the displacement of the recirculation bubble as the quarl angle varies that shows very good agreement with experiments.

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Section: Methodsmentioning

confidence: 99%

“…The reader is referred to Refs. [17], [22], and [23] for more details. Figure 1 shows a schematic of the Oxytec combustor.…”

Section: Methodsmentioning

confidence: 99%

Effects of a Diverging Cup on Swirl Number, Flow Pattern, and Topology of Premixed Flames

Degenève

Jourdaine

Mirat

et al. 2018

Journal of Engineering for Gas Turbines and Power

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show abstract

“…. This setup was also used to compare the stabilization of CO 2 -and N 2 -diluted oxy-methane flames and examine rules for switching between air-to oxy-combustion operating mode with the same injector [17,23]. Only the main elements of the test rig are briefly described below.…”

Section: Methodsmentioning

confidence: 99%

“…Only the main elements of the test rig are briefly described below. The reader is referred to [17,23,24] for more details. Figure 1 shows a schematic of the Oxytec combustor.…”

Section: Methodsmentioning

confidence: 99%

Effects of a Diverging Cup on Swirl Number, Flow Pattern and Topology of Premixed Flames

Degenève

Jourdaine

Mirat

et al. 2018

Volume 4B: Combustion, Fuels, and Emissions

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Impact of the diverging cup angle of a swirling injector on the flow pattern and stabilization of technically premixed flames is investigated both theoretically and experimentally with the help of laser diagnostics. Recirculation enhancement with a lower position of the internal recirculation zone and a flame leading edge protruding further upstream in the swirled flow are observed as the injector nozzle cup angle is increased. A theoretical analysis is carried out to examine if this could be explained by changes of the swirl level as the diffuser cup angle is varied. It is shown that pressure effects need in this case to be taken into account in the swirl number definition and expressions for its variation through a diffuser are derived. They indicate that changes of the swirl level including or not the pressure contribution to the axial momentum flux cannot explain the changes observed of the flow and flame patterns in the experiments. The swirl number without the pressure term, designated as pressure-less swirl, is then determined experimentally for a set of diffusers with increasing quarl angles under non-reacting conditions and the values found corroborate the predictions. It is finally shown that the decline of axial velocity and the rise of adverse axial pressure gradient, both due to the cross section area change through the diffuser cup, are the dominant effects that control the leading edge position of the internal recirculation zone of the swirled flow. This in turn is used to develop a model for the change of this position as the quarl angle varies that shows good agreement with experiments.

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“…Authors [21][22][23][24][25] studied the flow characteristics and mixing properties of the swirling double concentric jets at low Reynolds numbers with control discs. Jourdaine et al [26], investigated premixed swirling flames of CO 2 -CH 4 -O 2 and CH 4 -air using different optical diagnostics. Benim et al [27] studied numerically turbulent swirling flames in a model gas turbine combustor, using OpenFOAM code through the LES approach.…”

Section: Swirl Effects On Flamesmentioning

confidence: 99%

Introductory Chapter: Swirling Flows and Flames

Boushaki¹

2019

Swirling Flows and Flames

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Swirling flows are used in a very wide range of industrial applications. In non-reacting cases, examples of applications include vortex amplifiers and reactors, heat exchangers, jet pumps, cyclone separators, whirlpools, tornadoes, etc. In reacting cases, swirlers are widely used in combustion systems, such as gas turbines, industrial furnaces, boilers, gasoline and diesel engines and many other practical heating devices. Effects of using swirl on flow and combustion are significant and various and concern, for example, aerodynamics, mixing, flame stability, intensity of combustion and pollutant emissions. In this chapter, we are interested in the use of swirling flows in combustion systems. In industrial plants, the geometric methods of flame stabilization are based on increasing the residence time of reactive gases either by the wake effect bluff-body burner, by the flow rotation of reactants swirl burner or by a combination of these two mechanisms. Burners with helical flows generally referred to as the swirl burner have very wide applications in the industrial field. In the literature, many examples of uses of swirling jets are found as a means of controlling combustion [1-4]. Other studies focused on the swirl effect on the characteristics of lifted flames [5], stabilization and blow-out phenomenon [6-8] and pollutant emissions [9-13]. 2. Swirl generation techniques There are several ways to generate the rotation of a flow. They can be classified into three main categories:

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A comparison between the stabilization of premixed swirling CO 2 -diluted methane oxy-flames and methane/air flames

Cited by 41 publications

References 32 publications

Effects of a Diverging Cup on Swirl Number, Flow Pattern, and Topology of Premixed Flames

Effects of a Diverging Cup on Swirl Number, Flow Pattern, and Topology of Premixed Flames

Effects of a Diverging Cup on Swirl Number, Flow Pattern and Topology of Premixed Flames

Introductory Chapter: Swirling Flows and Flames

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