scholarly journals A numerical study of turbulent flame-wall interaction with reduced chemistry

2020 ◽  
Author(s):  
Rahul Palulli ◽  
Davy Brouzet ◽  
Mohsen Talei ◽  
Robert Gordon
Keyword(s):  
Numerical Study ◽  
Turbulent Flame ◽  
Reduced Chemistry ◽  
Wall Interaction

scholarly journals Numerical Study of the Instability and Flow Transition in a Vortex-Ring/Wall Interaction

2016 ◽  
Vol 9 (7) ◽  
pp. 2299-2309
Author(s):  
Heng Ren ◽  
G. X. Zhang ◽  
H. S. Guan ◽  
◽  
◽  
...  
Keyword(s):  
Vortex Ring ◽  
Numerical Study ◽  
Flow Transition ◽  
Wall Interaction

scholarly journals Numerical Study of a Turbulent Burner by Means of RANS and Detailed Chemistry

2019 ◽  
Vol 3 (2) ◽  
pp. 34
Author(s):  
Mohamed Hafid
Keyword(s):  
Schmidt Number ◽  
Numerical Study ◽  
Turbulent Flame ◽  
Navier Stokes ◽  
Turbulent Dissipation ◽  
Detailed Chemistry ◽  
Turbulent Schmidt Number ◽  
Complex Models ◽  
Pdf Model ◽  
Probability Density Function Pdf

The present paper shows a numerical study of the Co-flow turbulent flame configuration using the Reynolds Averaged Navier-Stokes (RANS) modelling with detailed chemistry. The presumed Probability Density Function (PDF) model combined with the k-Ɛ turbulence model is adopted. The GRI Mech-3.0 mechanism that involves 53 species and 325 reactions is used. The effect of the turbulent Schmidt number Sct and the C1ε constant in the turbulent dissipation transport equation is highlighted. Despite the simplicity of RANS approach compared to other complex models such as LES and DNS, the results show that this approach is still able to simulate the turbulent flame.

scholarly journals Numerical study of turbulent normal diffusion flame CH4-air stabilized by coaxial burner

2013 ◽  
Vol 17 (4) ◽  
pp. 1207-1219 ◽  
Author(s):  
Zouhair Riahi ◽  
Ali Mergheni ◽  
Jean-Charles Sautet ◽  
Ben Nasrallah
Keyword(s):  
Equivalence Ratio ◽  
Numerical Study ◽  
Mixture Fraction ◽  
Turbulent Flame ◽  
Flame Structure ◽  
Premixed Combustion ◽  
Air Jet ◽  
Fuel Jet ◽  
Jet Velocity ◽  
Lift Off

The practical combustion systems such as combustion furnaces, gas turbine, engines, etc. employ non-premixed combustion due to its better flame stability, safety, and wide operating range as compared to premixed combustion. The present numerical study characterizes the turbulent flame of methane-air in a coaxial burner in order to determine the effect of airflow on the distribution of temperature, on gas consumption and on the emission of NOx. The results in this study are obtained by simulation on FLUENT code. The results demonstrate the influence of different parameters on the flame structure, temperature distribution and gas emissions, such as turbulence, fuel jet velocity, air jet velocity, equivalence ratio and mixture fraction. The lift-off height for a fixed fuel jet velocity is observed to increase monotonically with air jet velocity. Temperature and NOx emission decrease of important values with the equivalence ratio, it is maximum about the unity.

Stochastic Model for the Investigation of the Effect of Inhomogeneities on Engine Knock

2004 ◽  
Author(s):  
Adina Gogan ◽  
Bengt Sunde´n ◽  
Harry Lehtiniemi ◽  
Fabian Mauss
Keyword(s):  
Stochastic Model ◽  
Turbulent Flame ◽  
Jump Process ◽  
Parameter Study ◽  
Zone Model ◽  
Gas Composition ◽  
Detailed Chemistry ◽  
Engine Knock ◽  
Turbulence Mixing ◽  
Wall Interaction

A stochastic model based on a probability density function (PDF) approach was developed for the investigation of spark ignition (SI) engine knock conditions. The model is based on a two zone model, where the burned and unburned gases are described as stochastic reactors, and the movement of the turbulent flame front is expressed with a Wiebe function. Using a stochastic particle ensemble to represent the PDF of the scalar variables associated with the burned and unburned gases, allows the consideration of inhomogeneities in gas composition and temperature, as well as turbulence mixing effects. The turbulent mixing is described with the interaction by exchange with the mean model. A stochastic jump process is used for modeling the heat transfer, hence accounting for the temperature fluctuations and the fluid wall interaction. Detailed chemistry is used in the calculations. A parameter study investigates the effects of end gas inhomogeneities related to residual gas composition and temperature, on the autoignition process.

Turbulent flame–wall interaction: a direct numerical simulation study

2010 ◽  
Vol 658 ◽  
pp. 5-32 ◽  
Author(s):  
A. GRUBER ◽  
R. SANKARAN ◽  
E. R. HAWKES ◽  
J. H. CHEN
Keyword(s):  
Numerical Simulation ◽  
Boundary Layer ◽  
Heat Flux ◽  
Direct Numerical Simulation ◽  
Turbulent Flame ◽  
Wall Heat Flux ◽  
Spatial And Temporal Patterns ◽  
Turbulent Structures ◽  
Wall Interaction ◽  
Near Wall

A turbulent flame–wall interaction (FWI) configuration is studied using three-dimensional direct numerical simulation (DNS) and detailed chemical kinetics. The simulations are used to investigate the effects of the wall turbulent boundary layer (i) on the structure of a hydrogen–air premixed flame, (ii) on its near-wall propagation characteristics and (iii) on the spatial and temporal patterns of the convective wall heat flux. Results show that the local flame thickness and propagation speed vary between the core flow and the boundary layer, resulting in a regime change from flamelet near the channel centreline to a thickened flame at the wall. This finding has strong implications for the modelling of turbulent combustion using Reynolds-averaged Navier–Stokes or large-eddy simulation techniques. Moreover, the DNS results suggest that the near-wall coherent turbulent structures play an important role on the convective wall heat transfer by pushing the hot reactive zone towards the cold solid surface. At the wall, exothermic radical recombination reactions become important, and are responsible for approximately 70% of the overall heat release rate at the wall. Spectral analysis of the convective wall heat flux provides an unambiguous picture of its spatial and temporal patterns, previously unobserved, that is directly related to the spatial and temporal characteristic scalings of the coherent near-wall turbulent structures.

scholarly journals Sound generation by turbulent premixed flames

2018 ◽  
Vol 843 ◽  
pp. 29-52 ◽  
Author(s):  
Ali Haghiri ◽  
Mohsen Talei ◽  
Michael J. Brear ◽  
Evatt R. Hawkes
Keyword(s):  
Numerical Study ◽  
Turbulent Flame ◽  
Premixed Flames ◽  
Computational Cost ◽  
Turbulent Flames ◽  
Far Field ◽  
Turbulent Premixed Flames ◽  
Acoustic Sources ◽  
Field Sound ◽  
Turbulent Premixed

This paper presents a numerical study of the sound generated by turbulent, premixed flames. Direct numerical simulations (DNS) of two round jet flames with equivalence ratios of 0.7 and 1.0 are first carried out. Single-step chemistry is employed to reduce the computational cost, and care is taken to resolve both the near and far fields and to avoid noise reflections at the outflow boundaries. Several significant features of these two flames are noted. These include the monopolar nature of the sound from both flames, the stoichiometric flame being significantly louder than the lean flame, the observed frequency of peak acoustic spectral amplitude being consistent with prior experimental studies and the importance of so-called ‘flame annihilation’ events as acoustic sources. A simple model that relates these observed annihilation events to the far-field sound is then proposed, demonstrating a surprisingly high degree of correlation with the far-field sound from the DNS. This model is consistent with earlier works that view a premixed turbulent flame as a distribution of acoustic sources, and provides a physical explanation for the well-known monopolar content of the sound radiated by premixed turbulent flames.

scholarly journals Large Eddy Simulation of a Premixed Flame in Hot Vitiated Crossflow With Analytically Reduced Chemistry

2018 ◽  
Author(s):  
Oliver Schulz ◽  
Nicolas Noiray
Keyword(s):  
Laminar Flame ◽  
Numerical Study ◽  
Flame Stabilization ◽  
Detailed Chemistry ◽  
Eddy Simulation ◽  
Jet In Crossflow ◽  
Air Jet ◽  
Reduced Chemistry ◽  
Large Eddy ◽  
Stable Flame

This numerical study deals with a premixed ethylene-air jet at 300 K injected into a hot vitiated crossflow at 1500 K and atmospheric pressure. The reactive jet in crossflow (RJICF) was simulated with compressible 3-D large eddy simulations (LES) with an analytically reduced chemistry (ARC) mechanism and the dynamic thickened flame (DTF) model. ARC enables simulations of mixed combustion modes, such as autoignition and flame propagation, that are both present in this RJICF. 0-D and 1-D simulations provide a comparison with excellent agreement between ARC and detailed chemistry in terms of autoignition time and laminar flame speed. The effect of the DTF model on autoignition was investigated for varying species compositions and mesh sizes. Comparisons between LES and experiments are in good agreement for average velocity distributions and jet trajectories; LES remarkably capture experimentally observed flame dynamics. An analysis of the simulated RJICF shows that the leeward propagating flame has a stable flame root close to the jet exit. The lifted windward flame, on the contrary, is anchored in an intermittent fashion due to autoignition flame stabilization. The windward flame base convects downstream and is “brought back” by autoignition alternately. These autoignition events occur close to a thin layer that is associated with radical build-up and that stretches down to the jet exit.

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