Large eddy simulation of dilute acetone spray flames using CMC coupled with tabulated chemistry

Combustion will play a major part in fulfilling the world’s energy demand in the next 20 years. Therefore, it is necessary to understand the fundamentals of the flame–wall interaction (FWI), which takes place in internal combustion engines or gas turbines. The FWI can increase heat losses, increase pollutant formations and lowers efficiencies. In this work, a Large Eddy Simulation combined with a tabulated chemistry approach is used to investigate the transient near wall behavior of a turbulent premixed stoichiometric methane flame. This sidewall quenching configuration is based on an experimental burner with non-homogeneous turbulence and an actively cooled wall. The burner was used in a previous study for validation purposes. The transient behavior of the movement of the flame tip is analyzed by categorizing it into three different scenarios: an upstream, a downstream and a jump-like upstream movement. The distributions of the wall heat flux, the quenching distance or the detachment of the maximum heat flux and the quenching point are strongly dependent on this movement. The highest heat fluxes appear mostly at the jump-like movement because the flame behaves locally like a head-on quenching flame.

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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

Volume 4B: Combustion, Fuels, and Emissions ◽

10.1115/gt2019-91396 ◽

2019 ◽

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 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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Prediction of Premixed Flame Dynamics Using Large Eddy Simulation With Tabulated Chemistry and Eulerian Stochastic Fields

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.4044996 ◽

2019 ◽

Vol 141 (11) ◽

Author(s):

Alexander Avdonin ◽

Alireza Javareshkian ◽

Wolfgang Polifke

Keyword(s):

Large Eddy Simulation ◽

Time Series Data ◽

Series Data ◽

Combustion Model ◽

Stochastic Fields ◽

Progress Variable ◽

Eddy Simulation ◽

Flame Dynamics ◽

Tabulated Chemistry ◽

Large Eddy

Abstract This paper demonstrates that a large Eddy simulation (LES) combustion model based on tabulated chemistry and Eulerian stochastic fields can successfully describe the flame dynamics of a premixed turbulent swirl flame. The combustion chemistry is tabulated from one-dimensional burner-stabilized flamelet computations in dependence on progress variable and enthalpy. The progress variable allows to efficiently include a detailed reaction scheme, while the dependence on enthalpy describes the effect of heat losses on the reaction rate. The turbulence-chemistry interaction is modeled by eight Eulerian stochastic fields. An LES of a premixed swirl burner with a broadband velocity excitation is performed to investigate the flame dynamics, i.e., the response of heat release rate to upstream velocity perturbations. In particular, the flame impulse response and the flame transfer function (FTF) are identified from LES time series data. Simulation results for a range of power ratings are in good agreement with the experimental data.

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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.

Download Full-text