Experimental Analysis of the Combustion Behavior of a Gas Turbine Burner by Laser Measurement Techniques

2010 ◽  
Vol 132 (5) ◽  
Author(s):  
Holger Ax ◽  
Ulrich Stopper ◽  
Wolfgang Meier ◽  
Manfred Aigner ◽  
Felix Güthe
Keyword(s):  
Gas Turbine ◽  
Mixture Fraction ◽  
Measurement Techniques ◽  
Elevated Pressure ◽  
Flame Stabilization ◽  
Single Shot ◽  
Laser Raman ◽  
Planar Laser ◽  
Industrial Gas Turbine ◽  
Gas Turbine Burner

Experimental results from optical and laser spectroscopic measurements on a scaled industrial gas turbine burner at elevated pressure are presented. Planar laser induced fluorescence on the OH radical and OH∗ chemiluminescence imaging were applied to natural gas/air flames for a qualitative analysis of the position and shape of the flame brush, the flame front and the stabilization mechanism. The results exhibit two different ways of flame stabilization, a conical more stable flame and a pulsating opened flame. For quantitative results, one-dimensional laser Raman scattering was applied to these flames and evaluated on an average and single-shot basis in order to simultaneously determine the major species concentrations, the mixture fraction, and the temperature. The mixing of fuel and air, as well as the reaction progress, could thus be spatially and temporally resolved, showing differently strong variations depending on the flame stabilization mode and the location in the flame.

Experimental Analysis of the Combustion Behavior of a Gas Turbine Burner by Laser Measurement Techniques

2009 ◽  
Author(s):  
Holger Ax ◽  
Ulrich Stopper ◽  
Wolfgang Meier ◽  
Manfred Aigner ◽  
Felix Gu¨the
Keyword(s):  
Gas Turbine ◽  
Mixture Fraction ◽  
Measurement Techniques ◽  
Elevated Pressure ◽  
Flame Stabilization ◽  
Single Shot ◽  
Laser Raman ◽  
Planar Laser ◽  
Stable Flame ◽  
Industrial Gas Turbine

Experimental results from optical and laser spectroscopic measurements on a scaled industrial gas turbine (GT) burner at elevated pressure are presented. Planar laser induced fluorescence on the OH radical and OH* chemiluminescence imaging were applied to natural gas/air flames for a qualitative analysis of the position and shape of the flame brush, the flame front and the stabilization mechanism. The results exhibit two different ways of flame stabilization, a conical more stable flame and a pulsating opened flame. For quantitative results, 1D-laser Raman scattering was applied to these flames and evaluated on an average and single shot basis in order to simultaneously determine the major species concentrations, the mixture fraction and the temperature. The mixing of fuel and air as well as the reaction progress could thus be spatially and temporally resolved, showing differently strong variations depending on the flame stabilization mode and the location in the flame.

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.

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.

Laser-Based Investigations of Thermoacoustic Instabilities in a Lean Premixed Gas Turbine Model Combustor

2006 ◽  
Vol 129 (3) ◽  
pp. 664-671 ◽  
Author(s):  
Peter Weigand ◽  
Wolfgang Meier ◽  
Xuru Duan ◽  
Manfred Aigner
Keyword(s):  
Gas Turbine ◽  
Mixture Fraction ◽  
Measurement Techniques ◽  
Pressure Fluctuations ◽  
Three Dimensional ◽  
Joint Probability ◽  
Optical Measurements ◽  
Laser Raman ◽  
Lean Premixed ◽  
Turbine Model

Nonintrusive laser-based and optical measurements were performed in a gas turbine model combustor with a lean premixed swirl-stabilized CH4-air flame at atmospheric pressure. The main objective was to gain spatially and temporally resolved experimental data to enable the validation of numerical CFD results of oscillating flames. The investigated flame was operated at 25 kW and ϕ=0.70, and exhibited self-excited oscillations of more than 135 dB at ≈300Hz. The applied measurement techniques were three-dimensional (3D) laser doppler velocimetry (LDV) for velocity measurements, OH* chemiluminescence yielding information about the heat release and pointwise laser Raman scattering for the determination of joint probability density functions (PDFs) of the major species concentrations, temperature, and mixture fraction. Each of these techniques was applied with phase resolution with respect to the periodic fluctuation of the pressure in the combustion chamber that was measured with a microphone probe. The measurements finally revealed that the mixing of fuel and air in this technical premixing system was strongly affected by the pressure fluctuations leading to changes in equivalence ratio during an oscillation cycle that, in turn, induced the pressure fluctuations.

Flow Field and Combustion Characterization of Premixed Gas Turbine Flames by Planar Laser Techniques

2008 ◽  
Author(s):  
Ulrich Stopper ◽  
Manfred Aigner ◽  
Wolfgang Meier ◽  
Rajesh Sadanandan ◽  
Michael Sto¨hr ◽  
...  
Keyword(s):  
Flow Field ◽  
Gas Turbine ◽  
Shear Layers ◽  
Diagnostic Methods ◽  
Single Shot ◽  
Mean Flow ◽  
Planar Laser ◽  
Primary Reactions ◽  
Reaction Zones ◽  
Industrial Gas Turbine

Lean premixed natural gas/air flames produced by an industrial gas turbine burner were analyzed using laser diagnostic methods. For this purpose, the burner was equipped with an optical combustion chamber and operated with preheated air at various thermal powers P, equivalence ratios Φ, and pressures up to p = 6 bar. For the visualization of the flame emissions OH* chemiluminescence imaging was applied. Absolute flow velocities were measured using particle image velocimetry (PIV), and the reaction zones as well as regions of burnt gas were characterized by planar laser induced fluorescence (PLIF) of OH. Using these techniques, the combustion behavior was characterized in detail. The mean flow field could be divided into different regimes: the inflow, a central and an outer recirculation zone, and the outgoing exhaust flow. Single-shot PIV images demonstrated that the instantaneous flow field was composed of small and medium sized vortices, mainly located along the shear layers. The chemiluminescence images reflected the regions of heat release. From the PLIF images it was seen that the primary reactions are located in the shear layers between the inflow and the recirculation zones and that the appearance of the reaction zones changed with flame parameters.

Laser Based Investigations of Thermo-Acoustic Instabilities in a Lean Premixed Gas Turbine Model Combustor

2006 ◽  
Author(s):  
Peter Weigand ◽  
Wolfgang Meier ◽  
Xuru Duan ◽  
Manfred Aigner
Keyword(s):  
Gas Turbine ◽  
Mixture Fraction ◽  
Measurement Techniques ◽  
Pressure Fluctuations ◽  
Optical Measurements ◽  
Laser Raman ◽  
Lean Premixed ◽  
Phase Resolution ◽  
Acoustic Instabilities ◽  
Turbine Model

Non-intrusive laser-based and optical measurements were performed in a gas turbine model combustor with a lean premixed swirl-stabilized CH4-air flame at atmospheric pressure. The main objective was to gain spatially and temporally resolved experimental data to enable the validation of numerical CFD-results of oscillating flames. The investigated flame was operated at 25 kW and φ = 0.70 and exhibited self-excited oscillations of more than 135 dB at about 300 Hz. The applied measurement techniques were 3-D LDV for velocity measurements, OH* chemiluminescence yielding information about the heat release, and point-wise laser Raman scattering for the determination of joint PDFs of the major species concentrations, temperature, and mixture fraction. Each of these techniques was applied with phase resolution with respect to the periodic fluctuation of the pressure in the combustion chamber that was measured with a microphone probe. The measurements finally revealed that the mixing of fuel and air in this technical premixing system was strongly affected by the pressure fluctuations leading to changes in equivalence ratio during an oscillation cycle which in turn induced the pressure fluctuations.

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.

Flow Field and Combustion Characterization of Premixed Gas Turbine Flames by Planar Laser Techniques

2008 ◽  
Vol 131 (2) ◽  
Author(s):  
Ulrich Stopper ◽  
Manfred Aigner ◽  
Wolfgang Meier ◽  
Rajesh Sadanandan ◽  
Michael Stöhr ◽  
...  
Keyword(s):  
Flow Field ◽  
Gas Turbine ◽  
Shear Layers ◽  
Diagnostic Methods ◽  
Single Shot ◽  
Mean Flow ◽  
Planar Laser ◽  
Primary Reactions ◽  
Reaction Zones ◽  
Industrial Gas Turbine

Lean premixed natural gas/air flames produced by an industrial gas turbine burner were analyzed using laser diagnostic methods. For this purpose, the burner was equipped with an optical combustion chamber and operated with preheated air at various thermal powers P, equivalence ratios Φ, and pressures up to p=6 bars. For the visualization of the flame emissions OH∗ chemiluminescence imaging was applied. Absolute flow velocities were measured using particle image velocimetry (PIV), and the reaction zones as well as regions of burnt gas were characterized by planar laser-induced fluorescence (PLIF) of OH. Using these techniques, the combustion behavior was characterized in detail. The mean flow field could be divided into different regimes: the inflow, a central and an outer recirculation zone, and the outgoing exhaust flow. Single-shot PIV images demonstrated that the instantaneous flow field was composed of small and medium sized vortices, mainly located along the shear layers. The chemiluminescence images reflected the regions of heat release. From the PLIF images it was seen that the primary reactions are located in the shear layers between the inflow and the recirculation zones and that the appearance of the reaction zones changed with flame parameters.

Monte Carlo Simulation for Radiative Transfer in a High-Pressure Industrial Gas Turbine Combustion Chamber

2017 ◽  
Author(s):  
Tao Ren ◽  
Michael F. Modest ◽  
Somesh Roy
Keyword(s):  
Monte Carlo ◽  
Gas Turbine ◽  
Radiation Effects ◽  
Swirling Flow ◽  
Calculation Model ◽  
Navier Stokes ◽  
Combustion Model ◽  
Stirred Reactor ◽  
Industrial Gas Turbine ◽  
Gas Turbine Burner

Radiative heat transfer is studied numerically for reacting swirling flow in an industrial gas turbine burner operating at a pressure of 15 bar. The reacting field characteristics are computed by Reynolds-averaged Navier-Stokes (RANS) equations using the k-ε model with the partially stirred reactor (PaSR) combustion model. The GRI-Mech 2.11 mechanism, which includes nitrogen chemistry, is used to demonstrate the the ability of reducing NOx emissions of the combustion system. A Photon Monte Carlo (PMC) method coupled with a line-by-line spectral model is employed to accurately account for the radiation effects. CO2, H2O and CO are assumed to be the only radiatively participating species and wall radiation is considered as well. Optically thin and PMC-gray models are also employed to show the differences between the simplest radiative calculation models and the most accurate radiative calculation model, i.e., PMC-LBL, for the gas turbine burner. It was found that radiation does not significantly alter the temperature level as well as CO2 and H2O concentrations. However, it has significant impacts on the NOx levels at downstream locations.

Synchronization During Multi-Mode Thermoacoustic Oscillations in a Liquid-Fueled Gas Turbine Combustor at Elevated Pressure

2019 ◽  
Author(s):  
Mitchell L. Passarelli ◽  
J. D. Maxim Cirtwill ◽  
Timothy Wabel ◽  
Adam M. Steinberg ◽  
A. J. Wickersham
Keyword(s):  
Heat Release ◽  
Gas Turbine ◽  
Heat Release Rate ◽  
Release Rate ◽  
High Speed ◽  
Elevated Pressure ◽  
Fuel Injector ◽  
Frequency Pulling ◽  
Industrial Gas Turbine ◽  
Thermoacoustic Oscillations

Abstract This paper analyzes intermittent self-excited thermoacoustic oscillations in which the pressure (P′) and heat release rate (q̇′) fluctuations are harmonically coupled. That is to say, P′ and q̇′ do not oscillate at the same frequencies, but rather at frequencies in integer ratios. Thus, this system represents a case dominated by nonlinear cross-mode coupling. The measurements were obtained in an optically-accessible combustor equipped with an industrial gas turbine fuel injector operating with liquid fuel under partially-premixed conditions at elevated pressure. High-speed chemiluminescence (CL) imaging of OH* was used as an indicator of the heat release rate. The data was processed using spectral proper orthogonal decomposition (SPOD) to isolate the dominant heat release and pressure modes. Synchronization theory was used to determine when the modes are coupled and how their interaction manifests in the measurements, particularly how it relates to the observed intermittency. The results show three distinct intervals of synchronized oscillation shared by all the mode pairs analyzed. The first interval exhibits the same characteristics as a pair of noisy, phase-locked self-oscillators, with phase-slipping and frequency-pulling. While the behaviour of the second interval differs among mode pairs, strong frequency-pulling is observed during the third interval for all pairs.

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