Computational investigation of a lifted hydrogen flame with LES and FGM

Within the framework of a Reynolds averaged numerical simulation (RANS) methodology for modeling turbulence, a comparative numerical study of turbulent lifted H 2 /N 2 flames is presented. Three different turbulent combustion models, namely, the eddy dissipation model (EDM), the eddy dissipation concept (EDC), and the composition probability density function (PDF) transport model, are considered in the analysis. A wide range of global and detailed combustion reaction mechanisms are investigated. As turbulence model, the Standard k-ε model is used, which delivered a comparatively good accuracy within an initial validation study, performed for a non-reacting H 2 /N 2 jet. The predictions for the lifted H 2 /N 2 flame are compared with the published measurements of other authors, and the relative performance of the turbulent combustion models and combustion reaction mechanisms are assessed. The flame lift-off height is taken as the measure of prediction quality. The results show that the latter depends remarkably on the reaction mechanism and the turbulent combustion model applied. It is observed that a substantially better prediction quality for the whole range of experimentally observed lift-off heights is provided by the PDF model, when applied in combination with a detailed reaction mechanism dedicated for hydrogen combustion.

show abstract

“…A sketch of the configuration is presented in Figure 2. [19,23]. The considered experimental conditions are listed in Table 1.…”

Section: Lifted H2/n2 Jet Flamementioning

confidence: 99%

Comparison of Combustion Models for Lifted Hydrogen Flames within RANS Framework

Benim

Pfeiffelmann

2019

Energies

Self Cite

View full text Add to dashboard Cite

show abstract

“…Premixed and non-premixed regions in swirl spray flames were analyzed with the flame index concept (Eckel et al 2019;Paulhiac et al 2020) and the influence of swirl number on the combustion regime (Fredrich et al 2019) was evaluated. It was used to study different coal flames (Tufano et al 2018;Wan et al 2019;Rieth et al 2019;, assess the stabilization mechanism of supersonic lifted flames (Bouheraoua et al 2017) and lifted hydrogen flames (Benim et al 2019), classify regions of industrial burners by the combustion regime , study auto-ignition of supercritical hydrothermal flames (Song et al 2019), analyze extinction and re-ignition events (Sripakagorn et al 2004) and gain insight into partially premixed DME flames . It was further applied to scram jets (Shen et al 2020;, Moderate or Intense Low oxygen Dilution (MILD) combustion (Amaduzzi et al 2020), compression ignition engines (An et al 2018), double-cone burners , coaxial diffusion flames , edge flames (Duboc et al 2019) and jet-in-hot-coflow flames in conjunction with tangential stretching rate analysis (Li et al 2019).…”

Section: Introductionmentioning

confidence: 99%

Identification of Flame Regimes in Partially Premixed Combustion from a Quasi-DNS Dataset

Zirwes

Zhang

Habisreuther

et al. 2020

Flow Turbulence Combust

View full text Add to dashboard Cite

Identifying combustion regimes in terms of premixed and non-premixed characteristics is an important task for understanding combustion phenomena and the structure of flames. A quasi-DNS database of the compositionally inhomogeneous partially premixed Sydney/Sandia flame in configuration FJ-5GP-Lr75-57 is used to directly compare different types of flame regime markers from literature. In the simulation of the flame, detailed chemistry and diffusion models are utilized and no turbulence and combustion models are used as the flame front and flow are fully resolved near the nozzle. This allows evaluating the regime markers as a post-processing step without modeling assumptions and directly comparing regime markers based on gradient alignment, drift term analysis and gradient free regime identification. The goal is not to find the correct regime marker, which might be impossible due to the different set of assumptions of every marker and the generally vague definition of the partially premixed regime itself, but to compare their behavior when applied to a resolved turbulent flame with partially premixed characteristics.

show abstract

“…In recent years, renewable energy sources have been increasingly used to cover energy demands as well as to develop heat transfer enhancement techniques [2][3][4][5]. Parallel to this tendency towards renewable energies, combustion continues to play a significant role [6,7]. Combustion also plays a vital role in the field of renewable energies, especially due to the significance of biomass [8,9], which is not only because it is a renewable primary energy source but also due to its CO 2 neutrality.…”

Section: Introductionmentioning

confidence: 99%

A Validation Study for RANS Based Modelling of Swirling Pulverized Fuel Flames

2021

Self Cite

View full text Add to dashboard Cite

A swirling pulverized coal flame is computationally investigated. A Eulerian–Lagrangian formulation is used to describe the two-phase flow. Turbulence is modelled within a RANS (Reynolds averaged numerical simulation) framework. Four turbulence viscosity- (TV) based models, namely the standard k-ε model, realizable k-ε model, renormalization group theory k-ε model, and the shear stress transport k-ω model are used. In addition, a Reynolds stress transport model (RSM) is employed. The models are assessed by comparing the predicted velocity fields with the measurements of other authors. In terms of overall average values, the agreement of the predictions to the measurements is observed to be within the range 20–40%. A better performance of the RSM compared to the TV models is observed, with a nearly twice as better overall agreement to the experiments, particularly for the swirl velocity. In the second part of the investigation, the resolution of the discrete particle phase in modelling the turbulent particle dispersion (TPD) and particle size distribution (SD) is investigated. Using the discrete random walk model for the TPD, it is shown that even five random walks are sufficient for an accuracy that is quite high, with a less than 1% mean deviation from the solution obtained by thirty random walks. The approximation of the measured SD is determined by a continuous Rosin–Rammler distribution function, and inaccuracies that can occur in its subsequent discretization are demonstrated and discussed. An investigation on the resolution of the SD by discrete particle size classes (SC) indicates that 12 SC are required for an accuracy with a less than 1% mean deviation from the solution with 18 SC. Although these numbers may not necessarily be claimed to be sufficiently universal, they may serve as guidance, at least for SD with similar characteristics.

show abstract

Computational investigation of a lifted hydrogen flame with LES and FGM

Cited by 18 publications

References 48 publications

Comparison of Combustion Models for Lifted Hydrogen Flames within RANS Framework

Comparison of Combustion Models for Lifted Hydrogen Flames within RANS Framework

Identification of Flame Regimes in Partially Premixed Combustion from a Quasi-DNS Dataset

A Validation Study for RANS Based Modelling of Swirling Pulverized Fuel Flames

Contact Info

Product

Resources

About