A new correlation between soot sheet width and soot volume fraction in turbulent non-premixed jet flames

2019 ◽  
Vol 37 (1) ◽  
pp. 927-934 ◽  
Author(s):  
S.M. Mahmoud ◽  
T.C. Lau ◽  
G.J. Nathan ◽  
P.R. Medwell ◽  
Z.T. Alwahabi ◽  
...  
Keyword(s):  
Volume Fraction ◽  
Soot Volume Fraction ◽  
Jet Flames ◽  
New Correlation ◽  
Sheet Width

Prediction of Soot Formation Trends in Turbulent Kerosene-Air Diffusion Jet Flames With Elevated Operating Pressure

2017 ◽  
Author(s):  
Pravin Nakod ◽  
Saurabh Patwardhan ◽  
Ishan Verma ◽  
Stefano Orsino
Keyword(s):  
Environmental Protection Agency ◽  
Volume Fraction ◽  
Soot Formation ◽  
Mixture Fraction ◽  
Soot Volume Fraction ◽  
Operating Pressure ◽  
Jet Flames ◽  
Emission Standard ◽  
Radial Profiles ◽  
Air Diffusion

Emission standard agencies are coming up with more stringent regulations on soot, given its adverse effect on human health. It is expected that Environmental Protection Agency (EPA) will soon place stricter regulations on allowed levels of the size of soot particles from aircraft jet engines. Since, aircraft engines operate at varying operating pressure, temperature and air-fuel ratios, soot fraction changes from condition to condition. Computation Fluid Dynamics (CFD) simulations are playing a key role in understanding the complex mechanism of soot formation and the factors affecting it. In the present work, soot formation prediction from numerical analyses for turbulent kerosene-air diffusion jet flames at five different operating pressures in the range of 1 atm. to 7 atm. is presented. The geometrical and test conditions are obtained from Young’s thesis [1]. Coupled combustion-soot simulations are performed for all the flames using steady diffusion flamelet model for combustion and Mass-Brookes-Hall 2-equation model for soot with a 2D axisymmetric mesh. Combustion-Soot coupling is required to consider the effect of soot-radiation interaction. Simulation results in the form of axial and radial profiles of temperature, mixture fraction and soot volume fraction are compared with the corresponding experimental measured profiles. The results for temperature and mixture fraction compare well with the experimental profiles. Predicted order of magnitude and the profiles of the soot volume fraction also compare well with the experimental results. The correct trend of increasing the peak soot volume fraction with increasing the operating pressure is also captured.

scholarly journals Effects of Fuel Molecular Weight on Emissions in a Jet Flame and a Model Gas Turbine Combustor

2017 ◽  
Vol 140 (3) ◽  
Author(s):  
Anandkumar Makwana ◽  
Suresh Iyer ◽  
Milton Linevsky ◽  
Robert Santoro ◽  
Thomas Litzinger ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Volume Fraction ◽  
Soot Formation ◽  
Premixed Flames ◽  
Soot Volume Fraction ◽  
Spatial Development ◽  
Gas Turbine Combustor ◽  
Jet Flames ◽  
Jet Flame ◽  
Model Gas Turbine Combustor

The objective of this study is to understand the effects of fuel volatility on soot emissions. This effect is investigated in two experimental configurations: a jet flame and a model gas turbine combustor. The jet flame provides information about the effects of fuel on the spatial development of aromatics and soot in an axisymmetric, co-flow, laminar flame. The data from the model gas turbine combustor illustrate the effect of fuel volatility on net soot production under conditions similar to an actual engine at cruise. Two fuels with different boiling points are investigated: n-heptane/n-dodecane mixture and n-hexadecane/n-dodecane mixture. The jet flames are nonpremixed and rich premixed flames in order to have fuel conditions similar to those in the primary zone of an aircraft engine combustor. The results from the jet flames indicate that the peak soot volume fraction produced in the n-hexadecane fuel is slightly higher as compared to the n-heptane fuel for both nonpremixed and premixed flames. Comparison of aromatics and soot volume fraction in nonpremixed and premixed flames shows significant differences in the spatial development of aromatics and soot along the downstream direction. The results from the model combustor indicate that, within experiment uncertainty, the net soot production is similar in both n-heptane and n-hexadecane fuel mixtures. Finally, we draw conclusions about important processes for soot formation in gas turbine combustor and what can be learned from laboratory-scale flames.

scholarly journals The effect of exit strain rate on soot volume fraction in turbulent non-premixed jet flames

2017 ◽  
Vol 36 (1) ◽  
pp. 889-897 ◽  
Author(s):  
S.M. Mahmoud ◽  
G.J. Nathan ◽  
Z.T. Alwahabi ◽  
Z.W. Sun ◽  
P.R. Medwell ◽  
...  
Keyword(s):  
Strain Rate ◽  
Volume Fraction ◽  
Soot Volume Fraction ◽  
Jet Flames

Effects of Fuel Molecular Weight on Emissions in a Jet Flame and a Model Gas Turbine Combustor

2017 ◽  
Author(s):  
Anandkumar Makwana ◽  
Suresh Iyer ◽  
Milton Linevsky ◽  
Robert Santoro ◽  
Thomas Litzinger ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Volume Fraction ◽  
Premixed Flames ◽  
Soot Volume Fraction ◽  
Spatial Development ◽  
Inlet Temperature ◽  
Gas Turbine Combustor ◽  
Jet Flames ◽  
Jet Flame ◽  
Model Gas Turbine Combustor

The objective of this study is to understand the effects of fuel volatility on soot emissions. The effect of fuel volatility on soot is investigated in two experimental configurations: a jet flame and a model gas turbine combustor. The jet flame experiment provides information about the effects of fuel on the spatial development of aromatics and soot in an axisymmetric, co-flow, laminar flame at atmospheric pressure. The data from the model gas turbine combustor illustrate the effect of fuel volatility on net soot production under conditions similar to an actual engine at cruise, operated at 5 atm, an inlet temperature of 560 K, and an inlet global equivalence ratio of 0.9 to 1.8. Two fuels with different boiling points are investigated: n-heptane/n-dodecane mixture and n-hexadecane/n-dodecane mixture. The n-hexadecane has a boiling point of 287° C as compared to 216° C for n-dodecane and 98° C for n-heptane. The jet flames investigated are non-premixed and premixed flames (jet equivalence ratios of 24 and 6) in order to have fuel rich conditions similar to those in the primary zone of an aircraft engine combustor. The results from the jet flames indicate that the peak soot volume fraction produced in the n-hexadecane fuel is slightly higher as compared to the n-heptane fuel for both non-premixed and premixed flames. The comparison of aromatics and soot volume fraction in non-premixed and premixed flames shows significant differences in the spatial development of aromatics and soot along the downstream direction. The results from the model combustor indicate that, within experiment uncertainty, the net soot production is similar in both n-heptane and n-hexadecane fuel mixtures. In comparing the results from these two burner configurations, we draw conclusions about important processes for soot formation in gas turbine combustors and what can be learned from laboratory-scale flames.

The effect of exit Reynolds number on soot volume fraction in turbulent non-premixed jet flames

2018 ◽  
Vol 187 ◽  
pp. 42-51 ◽  
Author(s):  
S.M. Mahmoud ◽  
G.J. Nathan ◽  
Z.T. Alwahabi ◽  
Z.W. Sun ◽  
P.R. Medwell ◽  
...  
Keyword(s):  
Reynolds Number ◽  
Volume Fraction ◽  
Soot Volume Fraction ◽  
Jet Flames

scholarly journals Effect of the Preheated Oxidizer Temperature on Soot Formation and Flame Structure in Turbulent Methane-Air Diffusion Flames at 1 and 3 atm: A CFD Investigation

Energies ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3671
Author(s):  
Subrat Garnayak ◽  
Subhankar Mohapatra ◽  
Sukanta K. Dash ◽  
Bok Jik Lee ◽  
V. Mahendra Reddy
Keyword(s):  
Mole Fraction ◽  
Air Temperature ◽  
Reaction Rate ◽  
Volume Fraction ◽  
Diffusion Flames ◽  
Soot Formation ◽  
Flame Structure ◽  
Soot Volume Fraction ◽  
Computational Domain ◽  
Pressure Elevation

This article presents the results of computations on pilot-based turbulent methane/air co-flow diffusion flames under the influence of the preheated oxidizer temperature ranging from 293 to 723 K at two operating pressures of 1 and 3 atm. The focus is on investigating the soot formation and flame structure under the influence of both the preheated air and combustor pressure. The computations were conducted in a 2D axisymmetric computational domain by solving the Favre averaged governing equation using the finite volume-based CFD code Ansys Fluent 19.2. A steady laminar flamelet model in combination with GRI Mech 3.0 was considered for combustion modeling. A semi-empirical acetylene-based soot model proposed by Brookes and Moss was adopted to predict soot. A careful validation was initially carried out with the measurements by Brookes and Moss at 1 and 3 atm with the temperature of both fuel and air at 290 K before carrying out further simulation using preheated air. The results by the present computation demonstrated that the flame peak temperature increased with air temperature for both 1 and 3 atm, while it reduced with pressure elevation. The OH mole fraction, signifying reaction rate, increased with a rise in the oxidizer temperature at the two operating pressures of 1 and 3 atm. However, a reduced value of OH mole fraction was observed at 3 atm when compared with 1 atm. The soot volume fraction increased with air temperature as well as pressure. The reaction rate by soot surface growth, soot mass-nucleation, and soot-oxidation rate increased with an increase in both air temperature and pressure. Finally, the fuel consumption rate showed a decreasing trend with air temperature and an increasing trend with pressure elevation.

Comparison of soot models for reacting sprays in diesel engine-like conditions

2021 ◽  
pp. 095440702110154
Author(s):  
Pavan Prakash Duvvuri ◽  
Rajesh Kumar Shrivastava ◽  
Sheshadri Sreedhara
Keyword(s):  
Experimental Data ◽  
Volume Fraction ◽  
Soot Volume Fraction ◽  
Modeling Framework ◽  
Aerosol Dynamics ◽  
Significant Difference ◽  
Polycyclic Aromatic ◽  
Order Of Magnitude ◽  
Detailed Kinetics ◽  
Soot Model

Stringent emission legislations and growing health concerns have contributed to the evolution of soot modeling in diesel engines from simple empirical relations to methods involving detailed kinetics and complex aerosol dynamics. In this paper, four different soot models have been evaluated for the high temperature, high pressure combusting dodecane spray cases of engine combustion network (ECN) spray A which mimics engine-relevant conditions. The soot models considered include an empirical, a multistep, a method of moments based, and a discrete sectional method soot model. Two experimental cases with ambient oxygen volume of 21% and 15% have been modeled. A good agreement between simulations and experiments for vapor penetration and heat release rate has been obtained. Quasi-steady soot volume fraction contours for the four soot models have been compared with experiments. Contours of the species and source terms involved in soot modeling have also been compared for a better understanding of soot processes. The empirical soot model results in higher magnitude and spread of soot due to a lack of modeling framework for oxidation through OH species. Among the four models studied, the multistep soot model has been observed to provide the most promising agreement with the experimental data in terms of distribution of soot and location of peak soot volume fraction. Due to a two-way coupling of soot models, the detailed models predict an upstream location for soot as compared to the multi-step soot model which is one way coupled. A significant difference (of an order of magnitude) in the concentration of PAH (polycyclic aromatic hydrocarbons) precursor between multistep and detailed soot models has been observed because of precursor consumption due to the coupling of detailed soot models with chemical kinetics. It is recommended that kinetic schemes, especially those concerning PAH, be validated with experimental data with a kinetics-coupled soot model.

Sign in / Sign up

Export Citation Format

Share Document