Flame Investigation of a Gas Turbine Central Pilot Body Burner at Atmospheric Pressure Conditions Using OH PLIF and High-Speed Flame Chemiluminescence Imaging

2015 ◽  
Author(s):  
Arman Ahamed Subash ◽  
Ronald Whiddon ◽  
Robert Collin ◽  
Marcus Aldén ◽  
Atanu Kundu ◽  
...  
Keyword(s):  
Residence Time ◽  
Atmospheric Pressure ◽  
High Speed ◽  
Combustion Products ◽  
Flame Stabilization ◽  
Operating Conditions ◽  
Time Resolved ◽  
Burner Exit ◽  
Planar Laser ◽  
Primary Combustion Products

Experiments were performed on the central pilot body (RPL-rich-pilot-lean) of Siemens prototype 4th generation DLE burner to investigate the flame behavior at atmospheric pressure condition when varying equivalence ratio, residence time and co-flow temperature. The flame at the RPL burner exit was investigated applying OH planar laser-induced fluorescence (PLIF) and high-speed chemiluminescence imaging. The results from chemiluminescence imaging and OH PLIF show that the size and shape of the flame are clearly affected by the variation in operating conditions. For both preheated and non-preheated co-flow cases, at lean equivalence ratios combustion starts early inside the burner and primary combustion comes to near completion inside the burner if residence time permits. For rich conditions, the unburnt fuel escapes out through the burner exit along with primary combustion products and combustion subsequently restarts downstream the burner at leaner condition and in a diffuse-like manner. For preheated co-flow, most of the operating conditions yield similar OH PLIF distributions and the flame is stabilizing at approximately the same spatial positions. It reveals the importance of the preheating co-flow for flame stabilization. Flame instabilities were observed and Proper Orthogonal Decomposition (POD) is applied to time resolved chemiluminescence data to demonstrate how the flame is oscillating. Preheating has strong influence on the oscillation frequency. Additionally, combustion emissions were analyzed to observe the effect on NOX level for variation in operating conditions.

Laser-Based Investigation on a Dry Low Emission Industrial Prototype Burner at Atmospheric Pressure Conditions

2016 ◽  
Author(s):  
Arman Ahamed Subash ◽  
Robert Collin ◽  
Marcus Aldén ◽  
Atanu Kundu ◽  
Jens Klingmann
Keyword(s):  
Atmospheric Pressure ◽  
Combustion Products ◽  
Flame Stabilization ◽  
Operating Conditions ◽  
Oh Radicals ◽  
Burner Exit ◽  
Planar Laser ◽  
Pilot Fuel ◽  
Intermediate Section ◽  
Primary Combustion Products

Experiments were performed at atmospheric pressure conditions on the prototype 4th generation DLE burner. The combustion changes that occur for alteration of the operating conditions by changing the equivalence ratios (ϕ) for CH4 as fuel at different sections of the burner, were optically investigated. The burner assembly has three concentrically arranged premixed burner sections: an outer Main section, an intermediate section (Pilot) and a central pilot body or pre-chamber combustor, called RPL (Rich-Pilot-Lean) section. All sections are facilitated to vary equivalence ratios to achieve optimal combustion. Planar laser-induced fluorescence (PLIF) of OH radicals and flame chemiluminescence imaging were applied to study the local flame characteristics in order to investigate turbulence-flame interaction and formation of reaction zone at the burner exit. The results show that the position and shape of the flame are clearly affected by the variation of equivalence ratios at different sections of the burner. During the experiments, first the RPL, then the Pilot and the Main flame were added in a step wise manner keeping constant the total air flow for the global ϕ = 0.5 in order to understand the flame contributions from the different combustion sections. It is observed that for the RPL fuel lean conditions, the primary combustion starts and reaches completion before exiting the burner throat while for rich conditions, the residual fuel escapes out through the RPL exit with primary combustion products and starts secondary combustion along with the Pilot and Main combustion. At the global ϕ = 0.5, for changing the RPL ϕ from lean to rich conditions, the flame stabilization region moves downstream of the burner exit and the flame front fluctuation along inner shear layer increases. For increasing the global ϕ and increasing the Pilot fuel ratio (PFR) without changing the RPL and the global ϕ, the total extension of the flame becomes shorter and the flame stabilization region moves upstream.

Experimental Investigation of the Influence of Burner Geometry on Flame Characteristics at a Dry Low Emission Industrial Prototype Burner at Atmospheric Pressure Conditions

2017 ◽  
Author(s):  
Arman Ahamed Subash ◽  
Robert Collin ◽  
Marcus Aldén ◽  
Atanu Kundu ◽  
Jens Klingmann
Keyword(s):  
Atmospheric Pressure ◽  
Recirculation Zone ◽  
Flame Stabilization ◽  
Operating Conditions ◽  
Oh Radicals ◽  
Flow Area ◽  
Burner Exit ◽  
Low Emission ◽  
Planar Laser ◽  
Conical Section

Laser based investigations were performed on a prototype 4th generation DLE (dry low emission) burner under atmospheric pressure conditions to study the effects of changing burner geometry on the flame. In a full burner configuration, a divergent conical section termed the Quarl is located after the burner exit for expanding the flow area and holding the flame. The planar laser-induced fluorescence (PLIF) of OH radicals together with the flame chemiluminescence imaging were employed to study the flame characteristics under the conditions with and without Quarl using CH4 as fuel to understand the influence of Quarl on the flame. When there is no Quarl, the flame has more freedom to expand at the burner exit and with an increase in the global equivalence ratio (ϕ), the width of the flame increases and the total extension of the flame shortens. For all the global ϕ considered here, the total extension of the flame is shorter under the condition without Quarl in comparison to the one with Quarl. For a richer global ϕ (ϕ ≥ 0.46) the outer recirculation zones (ORZs) are not observed under the condition with Quarl, but are observed without Quarl along with the inner recirculation zone. Without Quarl conditions, equivalence ratios (ϕ) of the concentrically arranged three sections of the burner: an outer Main section, an intermediate section (Pilot) and a central pilot body or pre-chamber combustor, termed the RPL (Rich-Pilot-Lean) sections were altered. The results show that at a constant global ϕ, with an increase in the RPL ϕ and the Pilot ϕ, the flame shortens and expands radially as well as the flame stabilization zone that is produced after the burner exit moves further downstream. At a richer global ϕ, the ORZ is observed along with the inner recirculation zone of the flame. Otherwise, with an increase in global ϕ, the changes in the flame shape, in the flame fluctuation and in the flame stabilization position follow similar trends as for increasing the Pilot ϕ and the RPL ϕ. Additionally, combustion emissions were obtained to observe the effects on NOX level for different operating conditions with and without Quarl.

Investigation of Fuel and Load Flexibility in a SGT-600/700/800 Burner Under Atmospheric Pressure Conditions Using High-Speed Oh-Plif and Oh Chemiluminescence Imaging

2021 ◽  
Author(s):  
Arman Ahamed Subash ◽  
Haisol Kim ◽  
Sven-Inge Möller ◽  
Mattias Richter ◽  
Christian Brackmann ◽  
...  
Keyword(s):  
Atmospheric Pressure ◽  
Gas Turbines ◽  
High Speed ◽  
Recirculation Zone ◽  
Burning Velocity ◽  
Flame Stabilization ◽  
Operating Conditions ◽  
Optical Measurements ◽  
Experimental Investigations ◽  
Pilot Fuel

Abstract Experimental investigations were performed using a standard 3rd generation dry low emission (DLE) burner under atmospheric pressure to study the effect of central and pilot fuel addition, load variations and H2 enrichment in a NG flame. High-speed OH-PLIF and OH-chemiluminescence imaging were employed to investigate the flame stabilization, flame turbulence interactions, and flame dynamics. Along with the optical measurements, combustion emissions were recorded to observe the effect of changing operating conditions on NOX level. The burner is used in Siemens industrial gas turbines SGT-600, SGT-700 and SGT-800 with minor hardware differences. This study thus is a step to characterize fuel and load flexibility for these turbines. Without pilot and central fuel injections in the current burner configuration, the main flame is stabilized creating a central recirculation zone. Addition of the pilot fuel strengthens the outer recirculation zone (ORZ) and moves the flame slightly downstream, whereas the flame moves upstream without affecting the ORZ when central fuel injection is added. The flame was investigated utilizing H2/NG fuel mixtures where the H2 amount was changed from 0 to 100%. The flame becomes more compact, the anchoring position moves closer to the burner exit and the OH signal distribution becomes more distinct for H2 addition due to increased reaction rate, diffusivity, and laminar burning velocity. Changing the load from part to base, similar trends were observed in the flame behavior but in this case due to the higher heat release because of increased turbulence intensity.

Investigation of Hydrogen Enriched Methane Flame in a Dry Low Emission Industrial Prototype Burner at Atmospheric Pressure Conditions

2017 ◽  
Author(s):  
Arman Ahamed Subash ◽  
Robert Collin ◽  
Marcus Aldén ◽  
Atanu Kundu ◽  
Jens Klingmann
Keyword(s):  
Atmospheric Pressure ◽  
Laminar Flame ◽  
Burning Velocity ◽  
Flame Stabilization ◽  
Oh Radicals ◽  
Burner Exit ◽  
Low Emission ◽  
Planar Laser ◽  
Pilot Fuel ◽  
Fuel Mixtures

Experiments were performed on a prototype 4th generation DLE (dry low emission) burner under atmospheric pressure conditions to investigate the effects of hydrogen (H2) enrichment on methane (CH4) flames. The burner assembly was designed to have three concentrically arranged premixed sections: an outer Main section, an intermediate section (Pilot) and a central pilot body termed the RPL (Rich-Pilot-Lean) section. The Planar laser-induced fluorescence (PLIF) of OH radicals together with flame chemiluminescence imaging were employed for studying the local flame characteristics so as to be able to investigate the turbulence-flame interactions and the location of the reaction zone at the burner exit. Flames were investigated for three different fuel mixtures having hydrogen (H2)/methane (CH4) in vol. % concentration of 0/100, 25/75 and 50/50. The results show that the characteristics of the flames are clearly affected by the addition of hydrogen and the effects are expected due to the faster reaction rate, higher diffusivity and higher laminar burning velocity of H2. Enriching the flame with H2 at a constant global phi (ϕ) is found to shorten the total extension of the flame due to the higher laminar flame speed. The OH signal distribution becomes thicker and more pronounced due to the higher production of OH radicals, and the flame stabilization zone that is produced after the burner throat, moves further downstream. At a constant global ϕ in altering the RPL and the Pilot ϕ, similar changes for both 0/100 and 25/75 (in vol. %) of the H2/CH4 fuel mixtures can be observed. At a rich RPL ϕ, the secondary RPL flame contributes to the main flame and to determining the flame stabilization position. The flame stabilization zone located after the burner throat moves further downstream with an increase in the RPL ϕ. When the PFR (Pilot fuel ratio) increases, the extension of the flame shortens and the flame stabilization zone moves upstream. Combustion emissions were also determined so as to observe the effects of the H2 enrichment on the NOX level.

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.

Investigation of Fuel and Load Flexibility in a SGT-600/700/800 Burner Under Atmospheric Pressure Conditions Using High-Speed OH-PLIF and OH Chemiluminescence Imaging

2020 ◽  
Author(s):  
Arman Ahamed Subash ◽  
Haisol Kim ◽  
Sven-Inge Möller ◽  
Mattias Richter ◽  
Christian Brackmann ◽  
...  
Keyword(s):  
Atmospheric Pressure ◽  
Gas Turbines ◽  
High Speed ◽  
Recirculation Zone ◽  
Flame Stabilization ◽  
Operating Conditions ◽  
Oh Radicals ◽  
Load Variations ◽  
Pilot Fuel ◽  
Industrial Gas Turbines

Abstract Fuel and load flexibility have been increasingly important features of industrial gas turbines in order to meet the demand for increased utilization of renewable fuels and to provide a way to balance the grid fluctuations due to the unsteady supply of wind and solar power. Experimental investigations were performed using a standard 3rd generation dry low emission (DLE) burner under atmospheric pressure conditions to study the effect of central and pilot fuel addition, load variations and hydrogen (H2) enrichment in a natural gas (NG) flame. High-speed kHz planar laser-induced fluorescence (PLIF) of OH radicals and imaging of OH chemiluminescence were employed to investigate the flame stabilization, flame turbulence interactions, and flame dynamics. Along with the optical measurements, combustion emissions were also recorded to observe the effect of changing operating conditions on NOX level. The burner is used in Siemens industrial gas turbines SGT-600, SGT-700 and SGT-800 with no hardware differences and the study thus is a step to characterize fuel and load flexibility for these turbines. Without pilot and central fuel injections in the current burner configuration, the main flame is stabilized creating a central recirculation zone (CRZ). Addition of the pilot fuel strengthens the outer recirculation zone (ORZ) and moves the flame anchoring position slightly downstream, whereas the flame moves upstream without affecting the ORZ when central fuel injection is added. The flame was investigated utilizing H2/NG fuel mixtures where the H2 amount was changed from 0 to 100%. The results show that the characteristics of the flames are clearly affected by the addition of H2 and by the load variations. The flame becomes more compact, the anchoring position moves closer to the burner exit and the OH signal distribution becomes more distinct for H2 addition due to increased reaction rate, diffusivity, and laminar burning velocity. Changing the load from part to base, similar trends were observed in the flame behavior but in this case due to the higher heat release because of increased turbulence intensity.

scholarly journals The Influence of Carrier Air Preheating on Autoignition of Inline-Injected Hydrogen–Nitrogen Mixtures in Vitiated Air of High Temperature

2017 ◽  
Vol 140 (3) ◽  
Author(s):  
Christoph A. Schmalhofer ◽  
Peter Griebel ◽  
Manfred Aigner
Keyword(s):  
Hydrogen Content ◽  
Gas Turbines ◽  
High Speed ◽  
Flame Stabilization ◽  
Operating Conditions ◽  
Promoting Effect ◽  
Experimental Conditions ◽  
Lean Premixed Combustion ◽  
Image Velocimetry ◽  
Fuel Mixtures

The use of highly reactive hydrogen-rich fuels in lean premixed combustion systems strongly affects the operability of stationary gas turbines (GT) resulting in higher autoignition and flashback risks. The present study investigates the autoignition behavior and ignition kernel evolution of hydrogen–nitrogen fuel mixtures in an inline co-flow injector configuration at relevant reheat combustor operating conditions. High-speed luminosity and particle image velocimetry (PIV) measurements in an optically accessible reheat combustor are employed. Autoignition and flame stabilization limits strongly depend on temperatures of vitiated air and carrier preheating. Higher hydrogen content significantly promotes the formation and development of different types of autoignition kernels: More autoignition kernels evolve with higher hydrogen content showing the promoting effect of equivalence ratio on local ignition events. Autoignition kernels develop downstream a certain distance from the injector, indicating the influence of ignition delay on kernel development. The development of autoignition kernels is linked to the shear layer development derived from global experimental conditions.

High Speed OH PLIF Measurements of Combustor Effusion Films in a High Pressure, Liquid Fueled Combustor

2021 ◽  
Author(s):  
Aravind Chandh ◽  
Shivam Patel ◽  
Oleksandr Bibik ◽  
Subodh Adhikari ◽  
David Wu ◽  
...  
Keyword(s):  
High Speed ◽  
Laser Sheet ◽  
Turbulent Flame ◽  
Combustion Products ◽  
Elevated Pressure ◽  
Inlet Temperature ◽  
Lean Burn ◽  
Jet Flame ◽  
Reduction Techniques ◽  
Planar Laser

Abstract This paper presents measurements of 10 kHz OH planar laser induced fluorescence (PLIF) with an objective to study the interaction of effusion cooling with the flame and hot combustion products in the liquid fueled combustor. The combustor rig is a single sector representation a rich-burn/quick-quench/lean-burn (RQL) configuration. It consists of a swirl nozzle, dilution, and effusion jets. The rig is operated under realistic aircraft conditions, including elevated combustor inlet temperature, and elevated pressure. The PLIF laser sheet was arranged perpendicular and parallel to the liner at distinct liner locations. Parametric variations of important parameters, namely equivalence ratio, and effusion cooling air blowing ratio are conducted to investigate their effect on flame-effusion jet interactions. The PLIF images were analyzed using several data reduction techniques to de-noise the images and identify patterns in the effusion jet-flame interactions. Results show that the effusion jets are highly unsteady, interacting strongly with the turbulent flame from the swirl nozzle and the dilution jets. This work is an extension of recent effusion film mixing studies that were performed with acetone PLIF under non-reacting conditions.

Autoignition of Hydrogen / Natural Gas / Nitrogen Fuel Mixtures at Reheat Combustor Operating Conditions

2012 ◽  
Author(s):  
Julia Fleck ◽  
Peter Griebel ◽  
Manfred Aigner ◽  
Adam M. Steinberg
Keyword(s):  
Natural Gas ◽  
High Speed ◽  
Volume Fraction ◽  
Fluid Dynamic ◽  
Flame Stabilization ◽  
Operating Conditions ◽  
Mixing Zone ◽  
Fuel Injector ◽  
Jet Penetration ◽  
Penetration Depths

Previous autoignition studies at conditions relevant to reheat combustor operation have indicated that the presence of relatively small amounts of natural gas (NG) in H2/N2 fuel significantly changes the autoignition behavior. The present study further elucidates the influence of NG on autoignition, kernel propagation, and subsequent flame stabilization at conditions that are relevant for the practical operation of gas turbine reheat combustors (p = 15 bar, Tinlet > 1000 K, hot flue gas, appropriate residence times). The experimental investigation was carried out in a generic, optically accessible reheat combustor. Autoignition events in the mixing zone were recorded by a high-speed camera at frame rates of up to 30,000 fps. This paper describes the autoignition behavior as the H2 volume fraction is increased (decreasing NG) in a H2/NG/N2 fuel mixture for two different jet penetration depths. Additionally, the subsequent flame stabilization phenomena and the structure of the stabilized flame are discussed. The results reveal that autoignition kernels occurred even for the lowest H2 fuel fraction, but they did not initiate a stable flame in the mixing zone. Increasing the H2 volume fraction decreased the distance between the initial position of the autoignition kernels and the fuel injector, finally leading to flame stabilization. The occurrence of autoignition kernels at lower H2 volume fractions (H2/(H2+NG) < 85%) was not found to be significantly influenced by the fluid dynamic and mixing field differences related to the different jet penetration depths. In contrast, autoignition leading to flame stabilization was found to depend on jet penetration; flame stabilization occurred at lower H2 fractions for the higher jet penetration depth (H2/(H2+NG) ≈ 89 compared to H2/(H2+NG) ≈ 95 vol. %).

Low NOx Premixed Combustion of MBtu Fuels in a Research Burner

1997 ◽  
Vol 119 (3) ◽  
pp. 553-558 ◽  
Author(s):  
K. Do¨bbeling ◽  
A. Eroglu ◽  
D. Winkler ◽  
T. Sattelmayer ◽  
W. Keppel
Keyword(s):  
High Pressure ◽  
Quartz Glass ◽  
Atmospheric Pressure ◽  
Fuel Injection ◽  
Flame Stabilization ◽  
Premix Combustion ◽  
Planar Laser ◽  
Preliminary Study ◽  
Combustion Tests

The paper reports on the development and testing of a premix research burner for MBtu fuels. The burner has a quartz glass annular mixing section and a quartz, glass flame tube to allow visualization of the flame. A central lance is used to mount modules for fuel injection, swirl generation, and flame stabilization. This allows a large number of variants with different swirl strength, mixing section length, fuel injection geometry, and flameholder size and shape to be easily tested. Experiments have been performed at atmospheric pressure and under high-pressure conditions (14 bar pressure, 400°C air preheat temperature) for syngas with a H2/CO ratio of up to 5. In a preliminary study, the mixing quality of the tested variants has been assessed with planar laser-induced fluorescence (LIF). High-pressure combustion tests show that low NOx (<10 vppmd @ 15 percent O2) premix combustion of MBtu fuels under industrial GT conditions without dilution is feasible.

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