Turbulent scalar flux transport in head-on quenching of turbulent premixed flames: a direct numerical simulations approach to assess models for Reynolds averaged Navier Stokes simulations

In turbulent premixed flames, for the mixing at a molecular level of reactants and products on the flame surface, it is crucial to sustain the combustion. This mixing phenomenon is featured by the scalar dissipation rate, which may be broadly defined as the rate of micro-mixing at small scales. This term, which appears in many turbulent combustion methods, includes the Conditional Moment Closure (CMC) and the Probability Density Function (PDF), requires an accurate model. In this study, a mathematical closure for the conditional mean scalar dissipation rate, <Nc|ζ>, in Reynolds, Averaged Navier–Stokes (RANS) context is proposed and tested against two different Direct Numerical Simulation (DNS) databases having different thermochemical and turbulence conditions. These databases consist of lean turbulent premixed V-flames of the CH4-air mixture and stoichiometric turbulent premixed flames of H2-air. The mathematical model has successfully predicted the peak and the typical profile of <Nc|ζ> with the sample space ζ and its prediction was consistent with an earlier study.

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Using self-similar properties of turbulent premixed flames to downsize chemical tables in high-performance numerical simulations

Combustion Theory and Modelling ◽

10.1080/13647830802209710 ◽

2008 ◽

Vol 12 (6) ◽

pp. 1055-1088 ◽

Cited By ~ 8

Author(s):

Denis Veynante ◽

Benoît Fiorina ◽

Pascale Domingo ◽

Luc Vervisch

Keyword(s):

Numerical Simulations ◽

High Performance ◽

Premixed Flames ◽

Turbulent Premixed Flames ◽

Self Similar ◽

Turbulent Premixed

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Modelling of turbulent scalar flux in turbulent premixed flames based on DNS databases

Combustion Theory and Modelling ◽

10.1080/13647830500307477 ◽

2006 ◽

Vol 10 (1) ◽

pp. 39-55 ◽

Cited By ~ 61

Author(s):

S. Nishiki ◽

T. Hasegawa ◽

R. Borghi ◽

R. Himeno

Keyword(s):

Premixed Flames ◽

Scalar Flux ◽

Turbulent Premixed Flames ◽

Turbulent Premixed

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Direct evaluation of the subgrid scale scalar flux in turbulent premixed flames with conditioned dual-plane stereo PIV

Proceedings of the Combustion Institute ◽

10.1016/j.proci.2008.05.027 ◽

2009 ◽

Vol 32 (2) ◽

pp. 1723-1730 ◽

Cited By ~ 27

Author(s):

Sebastian Pfadler ◽

Johannes Kerl ◽

Frank Beyrau ◽

Alfred Leipertz ◽

Amsini Sadiki ◽

...

Keyword(s):

Premixed Flames ◽

Subgrid Scale ◽

Scalar Flux ◽

Turbulent Premixed Flames ◽

Direct Evaluation ◽

Dual Plane ◽

Turbulent Premixed

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Partially Averaged Navier-Stokes Turbulence Modeling of Flow in 5x5 PWR Fuel Assembly With Spacer Grid

Volume 8: Computational Fluid Dynamics (CFD); Nuclear Education and Public Acceptance ◽

10.1115/icone26-82366 ◽

2018 ◽

Author(s):

Giacomo Busco ◽

Yassin A. Hassan

Keyword(s):

Large Eddy Simulation ◽

Numerical Simulations ◽

Stokes Equations ◽

Direct Numerical Simulations ◽

Navier Stokes ◽

Spacer Grid ◽

Navier Stokes Equations ◽

Eddy Simulation ◽

Large Eddy ◽

Reynolds Averaged Navier Stokes

The highly turbulent flow inside a pressurized water reactor makes unpractical the use of scale resolving simulations, due to the large number of space and time turbulent structures. The high computational cost associated with typical large eddies simulations or direct numerical simulations techniques is unsuitable due to the large spatiotemporal resolution required. Partially averaged Navier-Stokes turbulence model is presented as bridging model between Reynolds averaged Navier-Stokes equations and direct numerical simulations. As filtered representation of the Navier-Stokes equations, the model is able to continuously shift its energy-based filter, inside the turbulence spectrum, being able to resolve the turbulent scales of interest. The choice of energy based cut-off filters gives the chance to directly impose the degree of needed resolution, where the most important large scales unsteadiness are resolved at minimal computational expenses. The partially averaged Navier-Stokes modelling approach has been tested for a Reynolds number of 14,000, inside a 5 × 5 fuel bundle, with a single spacer grid and split-type mixing vanes. Four different filters have been tested, whose resolution ranged from Reynolds averaged Navier-Stokes and large eddy simulation. A comparison with large eddy simulation will be presented. The results show that the partially averaged Navier-Stokes modeling produces results comparable to those of large eddy simulation when the appropriate cut-off energy filter is chosen. The turbulence models results will be compared with the available particle image velocimetry experimental data.

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Assessment of the validity of RANS knock prediction using the resonance theory

International Journal of Engine Research ◽

10.1177/1468087419846032 ◽

2019 ◽

Vol 21 (4) ◽

pp. 610-621 ◽

Cited By ~ 2

Author(s):

Corinna Netzer ◽

Lars Seidel ◽

Frédéric Ravet ◽

Fabian Mauss

Keyword(s):

Numerical Simulations ◽

Direct Numerical Simulations ◽

Large Eddy Simulations ◽

Navier Stokes ◽

Post Processing ◽

Resonance Theory ◽

Auto Ignition ◽

Engine Knock ◽

Large Eddy ◽

Reynolds Averaged Navier Stokes

Following the resonance theory by Bradley and co-workers, engine knock is a consequence of an auto-ignition in the developing detonation regime. Their detonation diagram was developed using direct numerical simulations and was applied in the literature to engine knock assessment using large eddy simulations. In this work, it is analyzed if the detonation diagram can be applied for post-processing and evaluation of predicted auto-ignitions in Reynolds-averaged Navier–Stokes simulations even though the Reynolds-averaged Navier–Stokes approach cannot resolve the fine structures resolved in direct numerical simulations and large eddy simulations that lead to the prediction of a developing detonation. For this purpose, an engine operating point at the knock limit spark advance is simulated using Reynolds-averaged Navier–Stokes and large eddy simulations. The combustion is predicted using the G-equation and the well-stirred reactor model in the unburnt gases based on a detailed gasoline surrogate reaction scheme. All the predicted ignition kernels are evaluated using the resonance theory in a post-processing step. According to the different turbulence models, the predicted pressure rise rates and gradients differ. However, the predicted ignition kernel sizes and imposed gas velocities by the auto-ignition event are similar, which suggests that the auto-ignitions predicted by Reynolds-averaged Navier–Stokes simulations can be given a meaningful interpretation within the detonation diagram.

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