Large eddy simulation of flame propagation from leakage of naphtha in a cracking furnace

Abstract The process of ignition in aero-engines raises many practical issues that need to be faced during the design process. Recent experiments and simulations have provided detailed insights on ignition in single-injector configurations and on the light-round sequence in annular combustors. It was shown that Large Eddy Simulation (LES) was able to reliably reproduce the physical phenomena involved in the ignition of both perfectly premixed and liquid spray flames. The present study aims at further extending the knowledge on flame propagation during the ignition of annular multiple injector combustors by focusing the attention on the effects of heat losses, which have not been accounted for in numerical calculations before. This problem is examined by developing Large Eddy Simulations of the light-round process with a fixed temperature at the solid boundaries. Calculations are carried out for a laboratory-scale annular system. Results are compared in terms of flame shape and light-round duration with available experiments and with an adiabatic LES serving as a reference. Wall heat losses lead to a significant reduction in the flame propagation velocity as observed experimentally. However, the LES underestimates this effect and leads to a globally shorter light-round. To better understand this discrepancy, the study focuses then on the analysis of the near wall region where the velocity and temperature boundary layers must be carefully described. An a-priori analysis underlines the shortcomings associated to the chosen wall law by considering a more advanced wall model that fully accounts for variable thermophysical properties and for the unsteadiness of the boundary layer.

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Impact of Wall Temperature in Large Eddy Simulation of Light-Round in an Annular Liquid Fueled Combustor and Assessment of Wall Models

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.4045341 ◽

2019 ◽

Vol 142 (1) ◽

Author(s):

S. Puggelli ◽

T. Lancien ◽

K. Prieur ◽

D. Durox ◽

S. Candel ◽

...

Keyword(s):

Large Eddy Simulation ◽

Flame Propagation ◽

A Priori ◽

Heat Losses ◽

Wall Region ◽

Fixed Temperature ◽

Flame Propagation Velocity ◽

Eddy Simulation ◽

Spray Flames ◽

Large Eddy

Abstract The process of ignition in aero-engines raises many practical issues that need to be faced during the design process. Recent experiments and simulations have provided detailed insights into ignition in single-injector configurations and on the light-round sequence in annular combustors. It was shown that large eddy simulation (LES) was able to reliably reproduce the physical phenomena involved in the ignition of both perfectly premixed and liquid spray flames. This study aims at further extending the knowledge on flame propagation during the ignition of annular multiple injector combustors by focusing the attention on the effects of heat losses, which have not been accounted for in numerical calculations before. This problem is examined by developing LESs of the light-round process with a fixed temperature at the solid boundaries. Calculations are carried out for a laboratory-scale annular system. Results are compared in terms of flame shape and light-round duration with available experiments and with an adiabatic LES serving as a reference. Wall heat losses lead to a significant reduction in the flame propagation velocity as observed experimentally. However, the LES underestimates this effect and leads to a globally shorter light-round. To better understand this discrepancy, the study focuses then on the analysis of the near wall region. An a priori analysis underlines the shortcomings associated with the chosen wall law by considering a more advanced wall model that fully accounts for variable thermophysical properties and for the unsteadiness of the boundary layer.

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Large eddy simulation of premixed hydrogen/methane/air flame propagation in a closed duct

International Journal of Hydrogen Energy ◽

10.1016/j.ijhydene.2018.01.045 ◽

2018 ◽

Vol 43 (7) ◽

pp. 3871-3884 ◽

Cited By ~ 29

Author(s):

Kai Zheng ◽

Minggao Yu ◽

Yunpei Liang ◽

Ligang Zheng ◽

Xiaoping Wen

Keyword(s):

Large Eddy Simulation ◽

Flame Propagation ◽

Eddy Simulation ◽

Large Eddy

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Large-Eddy Simulation of Light-Round in an Annular Combustor With Liquid Spray Injection and Comparison With Experiments

Volume 4A: Combustion, Fuels and Emissions ◽

10.1115/gt2017-64145 ◽

2017 ◽

Cited By ~ 1

Author(s):

Théa Lancien ◽

Kevin Prieur ◽

Daniel Durox ◽

Sébastien Candel ◽

Ronan Vicquelin

Keyword(s):

Large Eddy Simulation ◽

Flame Propagation ◽

High Speed ◽

Complex Geometry ◽

Numerical Study ◽

Ignition Process ◽

Two Phase ◽

Eddy Simulation ◽

Large Eddy ◽

Annular Combustor

A combined experimental and numerical study of light-round, defined as the flame propagation from burner to burner in an annular combustor, under perfectly premixed conditions has previously demonstrated the ability of large-eddy simulation (LES) to predict such ignition processes in a complex geometry using massively parallel computations. The present investigation aims at developing light-round simulations in a configuration closer to real applications by considering liquid n-heptane injection. The large-eddy simulation of the ignition sequence of a laboratory scale annular combustion chamber comprising sixteen swirled two-phase injectors is carried out with a mono-disperse Eulerian approach for the description of the liquid phase. The objective is to assess this modeling approach to describe the two-phase reactive flow during the ignition process. The simulation results are compared in terms of flame structure and light-round duration to the corresponding experimental images of the flame front recorded by a high-speed intensified CCD camera. The dynamics of the flow is also analyzed to identify and characterize mechanisms controlling flame propagation during the light-round process.

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A fractal-based flame propagation model for large eddy simulation

International Journal of Engine Research ◽

10.1177/1468087411405414 ◽

2011 ◽

Vol 12 (4) ◽

pp. 393-401 ◽

Cited By ~ 1

Author(s):

H Kosaka ◽

Y Nomura ◽

M Nagaoka ◽

M Inagaki ◽

M Kubota

Keyword(s):

Large Eddy Simulation ◽

Flame Propagation ◽

Propagation Model ◽

Eddy Simulation ◽

Large Eddy

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Large eddy simulation of flame propagation during the ignition process in an annular multiple-injector combustor

Fuel ◽

10.1016/j.fuel.2019.116402 ◽

2020 ◽

Vol 263 ◽

pp. 116402 ◽

Cited By ~ 2

Author(s):

Dongmei Zhao ◽

Yifan Xia ◽

Haiwen Ge ◽

Qizhao Lin ◽

Gaofeng Wang

Keyword(s):

Large Eddy Simulation ◽

Flame Propagation ◽

Ignition Process ◽

Eddy Simulation ◽

Large Eddy

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Large Eddy Simulation of the Ignition Performance in a Lean Burn Combustor

Volume 4B: Combustion, Fuels and Emissions ◽

10.1115/gt2015-43872 ◽

2015 ◽

Cited By ~ 1

Author(s):

Yingjie Qiao ◽

Ronghai Mao ◽

Yuzhen Lin

Keyword(s):

Large Eddy Simulation ◽

Flame Propagation ◽

Bluff Body ◽

Mixture Fraction ◽

Ignition Process ◽

Lean Burn ◽

Flamelet Model ◽

Flame Kernel ◽

Eddy Simulation ◽

Large Eddy

The ignition performance is a crucial issue for combustor design, especially when lean burn technologies are employed to reduce the NOx emission. Ignition is the initiation of a flame kernel followed by flame propagation and global establishment. The initiation of flame kernel is beyond the scope of this paper because it involves plasma formation process. The present investigation is mainly focused on flame front propagation which is modeled by solving a transport equation of reaction progress variable. Large eddy simulation (LES) with flamelet model has been employed to study the effect of various spark location under engine start condition. The numerical approach is validated by ignition experiments with turbulent bluff-body burner conducted by Ahmed and Mastorakos in Cambridge University. Mean and transient characteristics of velocity, mixture fraction and flame structures are compared with experimental data, to assess the accuracy of simulation in terms of flow structure, turbulent mixing and combustion performances. The validated LES model is then applied to study a series of physical locations of the spark plug in a single dome combustor. Successful and unsuccessful ignition sequences, time evolution of velocity and fuel/air ratio (FAR) of selected spots are recorded. Comparing the unsuccessful ignition with the successful ones, whether flame kernel enters into the CRZ and ignites the flammable mixture is a critical process which determines successful ignition. The evolution of flame kernel is correlated to flow field and fuel/air distribution to further analyze their effects on the ignition process. Since the process is highly transient, successful ignition is not only determined by parameters of spark location, but also influenced by the parameters throughout the flow path during flame propagation.

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