On the flame stabilization of turbulent lifted hydrogen jet flames in heated coflows near the autoignition limit: A comparative DNS study

2021 ◽  
Vol 233 ◽  
pp. 111584
Author(s):  
Ki Sung Jung ◽  
Seung Ook Kim ◽  
Tianfeng Lu ◽  
Jacqueline H. Chen ◽  
Chun Sang Yoo
Keyword(s):  
Flame Stabilization ◽  
Jet Flames

scholarly journals Global Features of Flame Stabilization in Turbulent Non-premixed Jet Flames in Vitiated Coflow

2015 ◽  
Author(s):  
Aravind Ramachandran ◽  
Daniel A. Tyler ◽  
Parth K. Patel ◽  
Venkateswaran Narayanaswamy ◽  
Kevin M. Lyons
Keyword(s):  
Flame Stabilization ◽  
Jet Flames ◽  
Global Features ◽  
Vitiated Coflow

Experimental Observations of Nitrogen Diluted Ethylene and Methane Jet Flames

2013 ◽  
Author(s):  
Andrew R. Hutchins ◽  
James D. Kribs ◽  
Richard D. Muncey ◽  
William A. Reach ◽  
Kevin M. Lyons
Keyword(s):  
Thermal Diffusivity ◽  
Higher Order ◽  
Flame Stabilization ◽  
Hydrocarbon Fuels ◽  
Jet Flames ◽  
Nitrogen Dilution ◽  
Fuel Mixtures ◽  
And Behavior ◽  
Ethylene Flames

While the liftoff mechanisms of nitrogen-diluted methane jet flames have been well documented, higher order fuels, such as ethylene, have not been studied as extensively with regards to flame stabilization and behavior. Higher order fuels generally burn more intensely, and thus produce much different stabilization patterns than those of simple hydrocarbon fuels, such as methane. The purpose of this study was to observe the effects of nitrogen dilution on ethylene combustion and compare to that witnessed in typical methane jet flames; specifically, the influence on the liftoff height, blowout, and flame chemiluminescence. Liftoff and blowout velocities were compared for various mixtures of ethylene without nitrogen. It was observed that the reason behind the varying stabilization patterns is due to the higher thermal diffusivity of ethylene as well the higher flame speeds that are characterized in the combustion of ethylene. Using a sequence of images from each mixture, the flame liftoff heights were recorded. Due to the strong chemiluminescence of ethylene flames, little fluctuation between liftoff parameters was observed, with respect the velocity; however, there was a significant effect on the liftoff height, with respect to dilution. Blowout for fuel mixtures was much more difficult to achieve due to the higher thermal diffusivity of ethylene, meaning the flame would stabilize at positions much farther downstream than those of simple hydrocarbon fuels.

scholarly journals High-Momentum Jet Flames at Elevated Pressure, C: Statistical Distribution of Thermochemical States Obtained From Laser-Raman Measurements

2020 ◽  
Vol 142 (7) ◽  
Author(s):  
Holger Ax ◽  
Oliver Lammel ◽  
Rainer Lückerath ◽  
Michael Severin
Keyword(s):  
Gas Turbine ◽  
Mixture Fraction ◽  
Turbulent Flame ◽  
Elevated Pressure ◽  
Flame Stabilization ◽  
Strong Mixing ◽  
Single Shot ◽  
High Momentum ◽  
Jet Flames ◽  
Laser Raman

Abstract A detailed investigation on flame structures and stabilization mechanisms of confined high momentum jet flames by one-dimensional (1D)-laser Raman measurements is presented. The flames were operated with natural gas (NG) at gas turbine relevant conditions in an optically accessible high-pressure test rig. The generic burner represents a full scale single nozzle of a high temperature FLOX® gas turbine combustor including a pilot stage. 1D-laser Raman measurements were performed on both an unpiloted and a piloted flame and evaluated on a single shot basis revealing the thermochemical states from unburned inflow conditions to burned hot gas in terms of average and statistical values of the major species concentrations, the mixture fraction and the temperature. The results show a distinct difference in the flame stabilization mechanism between the unpiloted and the piloted case. The former is apparently driven by strong mixing of fresh unburned gas and recirculated hot burned gas that eventually causes autoignition. The piloted flame is stabilized by the pilot stage followed by turbulent flame propagation. The findings help to understand the underlying combustion mechanisms and to further develop gas turbine burners following the FLOX concept.

Flame stabilization and soot emission of methane jet flames for CO2 diluted oxy-combustion at elevated pressure

2021 ◽  
Vol 231 ◽  
pp. 111490
Author(s):  
Jiseop Lee ◽  
Gyu Jin Hwang ◽  
Jeong Ik Lee ◽  
Aqil Jamal ◽  
Nam Il Kim
Keyword(s):  
Elevated Pressure ◽  
Flame Stabilization ◽  
Soot Emission ◽  
Jet Flames

Experimental Analysis of Confined Jet Flames by Laser Measurement Techniques

2012 ◽  
Vol 134 (4) ◽  
Author(s):  
Oliver Lammel ◽  
Michael Stöhr ◽  
Peter Kutne ◽  
Claudiu Dem ◽  
Wolfgang Meier ◽  
...  
Keyword(s):  
Experimental Analysis ◽  
Gas Turbines ◽  
Measurement Techniques ◽  
Combustion Products ◽  
Flame Stabilization ◽  
Operating Conditions ◽  
Laser Measurement ◽  
Jet Flames ◽  
Laser Raman ◽  
Air Jet

An experimental analysis of confined premixed turbulent methane/air and hydrogen/air jet flames is presented. A generic lab scale burner for high-velocity preheated jets equipped with an optical combustion chamber was designed and set up. The size and operating conditions were configured to enable flame stabilization by recirculation of hot combustion products. The geometry of the rectangular confinement and an off-center positioning of the jet nozzle were chosen to resemble one burner nozzle of a FLOX®-based combustor. The off-center jet arrangement caused the formation of a pronounced lateral recirculation zone similar to the one in previously investigated FLOX®-combustors (Lückerath et al., 2007. “FLOX® Combustion at High Pressure with Different Fuel Compositions,” ASME J. Eng. Gas Turbines Power, 130(1), pp. 011505; Lammel et al., 2010. “FLOX® Combustion at High Power Density and High Flame Temperatures,” ASME J. Eng. Gas Turbines Power, 132(12), p. 121503ff). The analysis was accomplished by different laser measurement techniques. Flame structures were visualized by OH* chemiluminescence imaging and planar laser-induced fluorescence of the OH radical. Laser Raman scattering was used to determine concentrations of the major species and the temperature. Velocity fields were measured with particle image velocimetry. Results of measurements in two confined jet flames are shown. The mixing of fresh gas with recirculating combustion products and the stabilization of the methane flame are discussed in detail. The presented findings deliver important information for the understanding of confined jet flames operated with different fuels. The obtained data sets can be used for the validation of numerical simulations as well.

Large Eddy Simulation of Lifted Non-Premixed Jet Flames Using 2-Scalar Flamelet Model

2003 ◽  
Author(s):  
Mikikane Hirohata ◽  
Nobuyuki Taniguchi ◽  
Toshio Kobayashi
Keyword(s):  
Burning Velocity ◽  
Velocity Model ◽  
Flame Stabilization ◽  
Premixed Combustion ◽  
Premixed Flame ◽  
Jet Flames ◽  
Flamelet Model ◽  
The Difference ◽  
Partially Premixed Flame ◽  
Lift Off

In this paper we introduce the LES of lifted non-premixed jet flames based on two-scalar flamelet modeling. The flamelet G-equation for premixed combustion and the conserved scalar equation for non-premixed combustion are combined to express partially premixed flame propagation. In order to close filtered G-equation, the subgrid burning velocity model is proposed based on the concept that small triple flamelet are projected into unburnt gas from the flame-base of the lifted non-premixed flame. The calculation results are shown that wrinkling lifted flames are simulated and the difference of the lift-off height and the flame-shape with the variation of the co-flowing velocity is predicted. It is also confirmed that the conditional axial velocity near the flame base which is thought to relate the condition of the flame stabilization is on the order of two–three times of the laminar burning velocity, which agrees well with the experimental data. We hope that this method will be useful to investigate the flame stabilizing mechanism or flame controls of practical non-premixed jet flames.

High Momentum Jet Flames at Elevated Pressure: Part C — Statistical Distribution of Thermochemical States Obtained From Laser-Raman-Measurements

2019 ◽  
Author(s):  
Holger Ax ◽  
Oliver Lammel ◽  
Rainer Lückerath ◽  
Michael Severin
Keyword(s):  
Gas Turbine ◽  
Measurement Techniques ◽  
Flame Stabilization ◽  
Strong Mixing ◽  
Single Shot ◽  
High Momentum ◽  
Jet Flames ◽  
Data Set ◽  
Laser Raman ◽  
Flame Structures

Abstract A detailed investigation on flame structures and stabilization mechanisms of confined high momentum jet flames by 1D-laser Raman measurements is presented. The flames were operated with natural gas (NG) at gas turbine relevant conditions in an optically accessible high pressure test rig. The generic burner represents a full scale single nozzle of a high temperature FLOX® gas turbine combustor including a pilot stage. 1D-laser Raman measurements were performed on both an unpiloted and a piloted flame and evaluated on a single shot basis revealing the thermochemical states from unburned inflow conditions to burned hot gas in terms of average and statistical values of the major species concentrations, the mixture fraction and the temperature. The results are supported by complementary measurement techniques that have been previously conducted and presented in the connected papers part A and B [1,2], such as OH*-chemiluminescence, planar laser-induced fluorescence (PLIF) and particle image velocimetry (PIV), that combine to a big picture of the flame structures and help to interpret the results. The results show a distinct difference in the flame stabilization mechanism between the unpiloted and the piloted case. The former is apparently driven by strong mixing of fresh unburned gas and recirculated hot burned gas that eventually causes autoignition. The piloted flame is stabilized by the pilot stage followed by turbulent flame propagation. The findings help to understand the underlying combustion mechanisms and to further develop gas turbine burners following the FLOX® concept. The combined results of all measurement techniques that have been applied to these two flames thus form a unique and comprehensive data set for the validation of numerical simulation models.

Experimental Analysis of Confined Jet Flames by Laser Measurement Techniques

2011 ◽  
Author(s):  
Oliver Lammel ◽  
Michael Sto¨hr ◽  
Peter Kutne ◽  
Claudiu Dem ◽  
Wolfgang Meier ◽  
...  
Keyword(s):  
Experimental Analysis ◽  
Measurement Techniques ◽  
Combustion Products ◽  
Flame Stabilization ◽  
Operating Conditions ◽  
Laser Measurement ◽  
Jet Flames ◽  
Laser Raman ◽  
Air Jet ◽  
Planar Laser

An experimental analysis of confined premixed turbulent methane/air and hydrogen/air jet flames is presented. A generic lab scale burner for high-velocity preheated jets equipped with an optical combustion chamber was designed and set up. The size and operating conditions were configured to enable flame stabilization by recirculation of hot combustion products. The geometry of the rectangular confinement and an off-center positioning of the jet nozzle were chosen to resemble one burner nozzle of a FLOX®-based combustor. The off-center jet arrangement caused the formation of a pronounced lateral recirculation zone similar to the one in previously investigated FLOX®-combustors [1, 2]. The analysis was accomplished by different laser measurement techniques. Flame structures were visualized by OH* chemiluminescence imaging and planar laser-induced fluorescence of the OH radical. Laser Raman scattering was used to determine concentrations of the major species and the temperature. Velocity fields were measured with particle image velocimetry. Results of measurements in two confined jet flames are shown. The mixing of fresh gas with recirculating combustion products and the stabilization of the methane flame are discussed in detail. The presented findings deliver important information for the understanding of confined jet flames operated with different fuels. The obtained data sets can be used for the validation of numerical simulations as well.

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