Regimes of Spray Vaporization and Combustion in Counterflow Configurations

Liñán, A.; Martínez-Ruiz, Daniel; Sánchez, Antonio L.; Urzay, Javier

doi:10.1080/00102202.2014.971949

Cited by 15 publications

(6 citation statements)

References 35 publications

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“…Radially, the region extends up to r/R ≈ 0.3 for α = 0.5 and r/R ≈ 0.5 for α ≥ 1 ( Figure 5). Our results are in good qualitative agreement with the observations in the work of Liñán,19 where the potential flow region was reported to extend up to r/R = 0.5 in counterflow configurations with α = 0.5 and Re D > 1000.…”

Section: The Stagnation Point Region and The Strain Rate Parametersupporting

confidence: 82%

“…A review of analytical, 17 numerical, [12][13][14]19 and experimental results 7,10,15 indicates that the flow field is controlled primarily by the separation ratio and, to a lesser extent, by the Reynolds number. The effect of the nozzle geometry is also apparent, whereby contoured nozzles, rather than straight ones, are adopted in order to inhibit the growth of the boundary layer on the interior walls.…”

Section: Introductionmentioning

confidence: 99%

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Reynolds number and geometry effects in laminar axisymmetric isothermal counterflows

Scribano

Bisetti

2016

Physics of Fluids

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The counterflow configuration is a canonical stagnation flow, featuring two opposed impinging round jets and a mixing layer across the stagnation plane. Although counterflows are used extensively in the study of reactive mixtures and other applications where mixing of two streams is required, quantitative data on the scaling properties of the flow field are lacking. The aim of this work is to characterize the velocity and mixing fields in isothermal counterflows over a wide range of conditions. The study features both experimental data from particle image velocimetry and results from detailed axisymmetric simulations. The scaling laws for the nondimensional velocity and mixture fraction are obtained as a function of an appropriate Reynolds number and the ratio of the separation distance of the nozzles to their diameter. In the range of flow configurations investigated, the nondimensional fields are found to depend primarily on the separation ratio and, to a lesser extent, the Reynolds number. The marked dependence of the velocity field with respect to the separation ratio is linked to a high pressure region at the stagnation point. On the other hand, Reynolds number effects highlight the role played by the wall boundary layer on the interior of the nozzles, which becomes less important as the separation ratio decreases. The normalized strain rate and scalar dissipation rate at the stagnation plane are found to attain limiting values only for high values of the Reynolds number. These asymptotic values depend markedly on the separation ratio and differ significantly from the values produced by analytical models. The scaling of the mixing field does not show a limiting behavior as the separation ratio decreases to the smallest practical value considered. Published by AIP Publishing. [http://dx

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Section: The Stagnation Point Region and The Strain Rate Parametersupporting

confidence: 82%

Section: Introductionmentioning

confidence: 99%

Reynolds number and geometry effects in laminar axisymmetric isothermal counterflows

Scribano

Bisetti

2016

Physics of Fluids

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“…Then, scalar coordinate systems have been used systematically in flame theory, up to fuel-spray flames [4]. Composition or scalar space coordinates were also introduced for turbulent combustion modeling, in diffusion flamelets [5,6], in premixed flamelets [7][8][9], in conditional moment closure (CMC) [10] or again in the transport of probability density functions (PDF) [11][12][13].…”

Section: Introductionmentioning

confidence: 99%

“…4 -and C 2 H 5 OH-flames). Also other progress variable definitions would yield accurate flamelet results, often a combination of product (positive weight in definition) and educt species (negative weight) is suitable.…”

mentioning

confidence: 99%

A self-contained composition space solution method for strained and curved premixed flamelets

Scholtissek

Domingo

Vervisch

et al. 2019

Combustion and Flame

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Solving flames in scalar or composition space usually requires the modeling of scalar dissipation rates, or scalar gradients, which appear in the Jacobian of the transformation from the physical-space coordinates to the scalar space coordinates attached to the flame surface. Recently, Scholtissek et al. (2019) have discussed a self-contained solution for freely propagating premixed flames, in which the gradient distribution of the coordinate is also solved in scalar space. This approach is here extended to include curvature, strain and effects of unsteadiness. The resulting method is applied to a constant pressure and homogeneous ignition case, a stagnation flame, a tubular flame and a spherical expanding flame, capturing accurately effects of unsteadiness, strain and curvature. The results are systematically validated against physical-space solutions and experiments. In addition to the possibility of exploring these various canonical problems with a single set of equations, it is shown that another major outcome of this new formulation lies in the possibility of studying steady flames subjected to negative strain.

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“…Previous numerical calculations of laminar axisymmetric flow fields for chemically frozen impinging jets have considered either two identical jets [9,11] or the closely related problem of a jet impinging on flat wall [10,[12][13][14][15][16][17]. For the latter flow, the complete Navier-Stokes equations have been employed to address Reynolds-number dependences [10,15], verifying that for moderately large Re the flow structure approaches the inviscid solution [10], which can be computed with a stream-function/vorticity formulation [10, 12-14, 16, 17].…”

Section: Introductionmentioning

confidence: 99%

Aerodynamics of axisymmetric counterflowing jets

Carpio

Liñán²,

Sánchez

et al. 2017

Combustion and Flame

Self Cite

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The laminar flow resulting from impingement of two steadily fed low-Mach-number gaseous jets issuing into a stagnant atmosphere from coaxial cylindrical ducts at moderately large Reynolds numbers, often used in combustion experiments, is studied through numerical integrations of the Navier-Stokes equations. In the Reynolds-number range addressed, 50-1000, the flow of the approaching jets is nearly inviscid, with viscous effects and mixing being restricted to the thin mixing layers surrounding the jets and to a thin layer located at the separating stream surface. The analysis of the main inviscid flow shows that only two parameters, based on the scales associated with the radius and the velocity profiles of the two feed streams, are needed to characterize the flow, namely, the ratio of the inter-jet separation distance to the duct radius and the ratio of momentum fluxes of the jets. The numerical results for uniform and Poiseuille velocity profiles provide, in particular, the value of the strain rate at the stagnation point for use in the analysis of experimental studies of counterflow premixed and diffusion flames.

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Regimes of Spray Vaporization and Combustion in Counterflow Configurations

Abstract: This article addresses the problem of spray vaporization and combustion in axisymmetric opposed-jet configurations involving a stream of hot air counterflowing against

Cited by 15 publications

References 35 publications

Reynolds number and geometry effects in laminar axisymmetric isothermal counterflows

Reynolds number and geometry effects in laminar axisymmetric isothermal counterflows

A self-contained composition space solution method for strained and curved premixed flamelets

Aerodynamics of axisymmetric counterflowing jets

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