Progress in probability density function methods for turbulent reacting flows

Haworth, Daniel C.

doi:10.1016/j.pecs.2009.09.003

Cited by 532 publications

(304 citation statements)

References 345 publications

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“…As mentioned in the literature [41], the micromixing constant has a strong effect on RANS-PDF predictions, however it may not be so in LES due to considerably greater localization and reduced scalar variances. In this section the micro mixing effects are investigated in flame F2 with N=4.…”

Section: Sensitivity Analysis: Micromixingmentioning

confidence: 95%

“…The above time scale includes a molecular time scale, proportional to the diffusion coefficient (through µ), this fact combined with the molecular diffusion present in D e makes LES-PDF suitable for premix calculations. There are several alternative micromixing methods proposed mainly in the RANS context [40,41] however the increase in complexity and computational time required does not necessary guarantee improved predictions in LES context.…”

Section: Filtered Probability Density Functionmentioning

confidence: 99%

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Large Eddy Simulation of Premixed Turbulent Flames Using the Probability Density Function Approach

Dodoulas

Navarro‐Martinez

2013

Flow Turbulence Combust

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Abstract. In the present study a Large Eddy Simulation and Filtered Density Function model is applied to three premixed piloted turbulent methane flames at different Reynolds Numbers using the Eulerian stochastic fields approach. The model is able to reproduce the flame structure and flow characteristics with a low number of fields (between 4 and 16 fields). The results show a good agreement with experimental data with the same closures employed in non-premixed combustion without any adjustment for combustion regime. The effect of heat release on the flow field is captured correctly. A wide range of sensitivity studies is carried out, including the number of fields, the chemical mechanism, differential diffusion effects and micro-mixing closures. The present work shows that premixed combustion (at least in the conditions under study) can be modelled using LES-PDF methods.. Finally, the ability of the model to predict flame quenching is studied. The model can accurate capture the conditions at which combustion is not sustainable and large pockets of extinction appear.

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Section: Sensitivity Analysis: Micromixingmentioning

confidence: 95%

Section: Filtered Probability Density Functionmentioning

confidence: 99%

Large Eddy Simulation of Premixed Turbulent Flames Using the Probability Density Function Approach

Dodoulas

Navarro‐Martinez

2013

Flow Turbulence Combust

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“…Localized extinctions have been recently studied by Barlow et al [16] in piloted jet flames of CH 4 /H 2 /air, in comparable conditions. Accurate prediction of localized extinction is recognized as an important test of turbulent combustion models [17].…”

Section: Specific Objectivesmentioning

confidence: 99%

On the structure of the near field of oxy-fuel jet flames using Raman/Rayleigh laser diagnostics

Sevault

Dunn

Ditaranto

2012

Combustion and Flame

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An experimental study on turbulent non-premixed jet flames is presented with focus on CO 2 -diluted oxy-fuel combustion using a coflow burner. Measurements of local temperatures and concentrations of the main species CO 2 , O 2 , CO, N 2 , CH 4 , H 2 O and H 2 were achieved using the simultaneous line-imaged Raman/Rayleigh laser diagnostics setup at Sandia National Laboratories. Two series of flames burning mixtures of methane and hydrogen were investigated. In the first series, the hydrogen molar fraction in the fuel was varied from 37 to 55 %, with a constant jet exit Reynolds number Re Fuel of 15,000. In the second series the jet exit Reynolds number was varied from 12,000 to 18,000, while keeping 55 % H 2 molar fraction in the fuel. Besides local temperatures and concentrations, the results revealed insights on the behaviour of localized extinction in the near-field. It was observed that the degree of extinction increased as the hydrogen content in fuel was decreased and as the jet Reynolds number was increased. Based on the distribution of the temperature, a fully burning probability index able to quantify the degree of extinction along the streamwise coordinate was defined and applied to the present flame measurements. A comparison of measured conditional mean of mass fractions and laminar flame calculations underlined the significant level of differential diffusion in the near-field that tended to decrease farther downstream. The results also showed high local CO levels induced by the high content of CO 2 in the oxidizer and flame products. A shift of maximum flame temperature was observed toward the rich side of the mixture fraction space, most likely as a consequence of reduced heat release in the presence of product dissociation. Main characteristics of laser Raman scattering measurements in CO 2 -diluted oxy-fuel conditions compared to air-diluted conditions are also highlighted. Most data, including scalar fluctuations and conditional statistics are available upon request.

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“…The cause of this over-prediction may 341 be due to chemical mechanism validity range, since higher pressure and temperature are 342 found when increasing load. Also the lack of any turbulent-chemistry interaction model 343 may also contribute to this result [38]. Nevertheless, predicted in-cylinder pressure and 344…”

Section: Rcci Medium Load Operation 302mentioning

confidence: 99%

Operating range extension of RCCI combustion concept from low to full load in a heavy-duty engine

et al. 2015

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ElsevierMolina Alcaide, SA.; García Martínez, A.; Pastor Enguídanos, JM.; Belarte Mañes, E.; Balloul, I. (2015). Operating range extension of RCCI combustion concept from low to full load in a heavy-duty engine. Applied Energy. 143:211-227. doi:10.1016/j.apenergy.2015.01.035. overlimit function is used to select the best engine settings for each operating point. 23Finally, engine emissions and performance results from that RCCI operation are 24 compared with conventional Diesel combustion (CDC). 25Results suggest that double injection strategies should be used for RCCI operation from 26 low to mid load. However, from high to full load operation, single injection strategies 27 should be used, mainly to avoid excessive in-cylinder pressure gradients. In addition, it 28 is confirmed the suitability of RCCI combustion to overcome the soot-NOx trade-off 29 characteristic of CDC, from 6 to 24 bar of BMEP, while improving fuel consumption. 30

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Progress in probability density function methods for turbulent reacting flows

Cited by 532 publications

References 345 publications

Large Eddy Simulation of Premixed Turbulent Flames Using the Probability Density Function Approach

Large Eddy Simulation of Premixed Turbulent Flames Using the Probability Density Function Approach

On the structure of the near field of oxy-fuel jet flames using Raman/Rayleigh laser diagnostics

Operating range extension of RCCI combustion concept from low to full load in a heavy-duty engine

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