scholarly journals Development of a Swirl and Bluff-Body Stabilized Burner for Low-NOx, Lean-Premixed Combustion

1995 ◽  
Author(s):  
Jeffery A. Lovett ◽  
Warren J. Mick
Keyword(s):  
Bluff Body ◽  
Fuel Injection ◽  
Swirling Flow ◽  
Cylindrical Tube ◽  
Inlet Temperature ◽  
Lean Premixed Combustion ◽  
Fuel Injectors ◽  
Air Mixing ◽  
Low Nox Combustion ◽  
Heavy Duty Gas Turbine

A burner configuration utilizing both swirl and bluff-body stabilization was developed and tested for dry low-NOx combustion of natural gas fuel. A multiple number of these burners can be used to make up a can combustor. The burner consisted of a central hub supporting an axial swirler and spoke-type fuel injectors mounted coaxially within a 100 mm diameter cylindrical tube. The swirl typically provided strong recirculation and mixing, while the flame was anchored physically to the center hub. Tests were conducted at typical heavy-duty gas turbine conditions of 620 K inlet temperature and 10 atmospheres pressure. Parametric studies were conducted with various configurations of the burner to determine the corresponding effects on fuel-air mixing, flame stability, and NOx and CO emissions. The results show that ultra-low NOx emissions can be obtained if the fuel injection is sufficiently well distributed. The compact flame produced by the highly mixed swirling flow results in very low CO emissions as well. The results suggest also that swirl-strength is reduced in an upstream swirler configuration.

Effects of Swirler Configurations on Flow Structures and Combustion Characteristics

2004 ◽  
Author(s):  
Guoqiang Li ◽  
Ephraim J. Gutmark
Keyword(s):  
Fuel Injection ◽  
Vortex Breakdown ◽  
Swirling Flow ◽  
Combustion Characteristics ◽  
Pollutant Emissions ◽  
Flow Structures ◽  
Inlet Temperature ◽  
Nox Emissions ◽  
Atmospheric Conditions ◽  
Fuel Injector

Modern gas turbine combustion technologies are driven by stringent regulations on pollutant emissions such as CO and NOx. A combustion system of multiple swirlers coupled with distributed fuel injection was studied as a new concept for reducing NOx emissions by application of Lean Direct Injection (LDI) combustion. The present paper investigates the effects of swirler configurations on the flow structures in isothermal flow and combustion cases using a multiple-swirlers fuel injector at atmospheric conditions. The swirling flow field within the combustor was characterized by a central recirculation zone formed after vortex breakdown. The differences between the tangential and axial velocity profiles, the shape of the recirculation zones and the turbulence intensity distribution for the different fuel injector configurations impacted the flame structure, the temperature distribution and the emission characteristics both for gaseous and liquid fuels. Co-swirling configuration was shown to have the lowest NOx emission level compared with the counter-swirling ones for both types of fuels with lower inlet temperature. In contrast to this, the swirl configuration had less effect on the combustion characteristics in the case of gaseous fuel with high air inlet temperature. The differences in NOx emissions were shown to be closely related to the Damkohler number or the degree to which the flame resembled well-mixed combustion, which is the foundation for LDI combustion.

Numerical and Experimental Study of Geometry Effects on Fuel/Air Mixing and Combustion Characteristics of a DLN Burner

2020 ◽  
Author(s):  
Yan Zhao ◽  
Weiwei Shao ◽  
Yan Liu ◽  
Xiaodi Tang ◽  
Yunhan Xiao ◽  
...  
Keyword(s):  
Laser Doppler Velocimetry ◽  
Fuel Injection ◽  
Swirling Flow ◽  
Reaction Field ◽  
Mixing Performance ◽  
Lean Premixed Flames ◽  
Image Velocimetry ◽  
Planar Laser ◽  
Air Mixing ◽  
Radical Distribution

Abstract Swirling flow is widely used in gas turbine burners to promote fuel/air mixing uniformity and to stabilize lean premixed flames. In this study, numerical and experimental methods are utilized to investigate the effects of burner geometry on fuel/air mixing and combustion performance and to optimize the burner geometry. The premixed burner geometry parameters including air swirling angle and fuel injection diameter/angle are modified to achieve fuel/air mixture uniformity. Laser Doppler Velocimetry (LDV) and Particle Image Velocimetry (PIV) are adopted to examine the flow field, Planar Laser Induced Fluorescence (PLIF) for detecting OH radical distribution thus investigating the characteristics of the reaction field. Burners of different configurations are manufactured to conduct combustion experiments. The burner with the worst mixing performance can‘t ignite successfully. However, burners with better mixing performance have a homogeneous reaction field with less perturbance, and the NOX emission stays at a relatively low level around 2.5 ppm (15% O2) at the designed operating condition.

Numerical Re-Design of a Heavy Duty Gas Turbine Hydrogen-Fired Combustion Chamber

2010 ◽  
Author(s):  
Alessandro Marini ◽  
Giovanni Riccio ◽  
Francesco Martelli ◽  
Stefano Sigali ◽  
Stefano Cocchi
Keyword(s):  
Combustion Chamber ◽  
Gas Turbine ◽  
Fuel Injection ◽  
Nox Reduction ◽  
Airflow Rate ◽  
Heavy Duty ◽  
Air Mixing ◽  
Dry Conditions ◽  
Heavy Duty Gas Turbine ◽  
Full Scale Tests

The present work describes the numerical methodology followed to characterize and study modifications to a silo-type diffusive combustion chamber installed on a GE10, a 10 MW class heavy-duty gas turbine manufactured by GE Oil & Gas. The goal of the work was to investigate modifications to the combustion chamber to allow operation with 100% hydrogen fuel at reduced NOx production in dry conditions. The investigation focused mainly on the burner; the liner was not substantially changed. The swirler and the fuel injection holes were redesigned to achieve better fuel-air mixing and a higher airflow rate in the primary zone of the combustor, maintaining a diffusion flame scheme. The proposed modifications were analyzed using a 3D CFD RANS reactive procedure based on commercial codes. The method was previously validated by comparison with the experimental data from the full scale tests performed at the Enel Facility at Sesta, Italy. In-house codes were developed for the post-processing of the results. The numerical analysis has shown that the modified version can provide a NOx reduction up to 40%. The results are discussed focusing on the effect of fuel injection scheme on mixing quality and NOx emission containment.

scholarly journals Emissions Performance of a Ramburner Sector of a Mach 5 Combined-Cycle Engine

1995 ◽  
Author(s):  
Donald J. Hautman
Keyword(s):  
Equivalence Ratio ◽  
Fuel Injection ◽  
Flux Ratio ◽  
Mie Scattering ◽  
Combustion Efficiency ◽  
Combined Cycle ◽  
Orifice Diameter ◽  
Inlet Temperature ◽  
Nitric Oxides ◽  
Air Mixing

A research program was conducted to acquire and analyze data from a ramburner sector operating at conditions typical for a methane-fueled ramburner in a Mach 5 Turboramjet propulsion system. A combined experimental and analytical approach was used to obtain and interpret a data base suitable for ramburner design. Non-reacting Mie scattering measurements documented the fuel-air mixing as a function of fuel-injection geometry and flow conditions. Computational fluid dynamics calculations were shown to agree reasonably well with measured jet penetrations, but overpredicted the rate of mixing. An equation to calculate the average equivalence ratio as a function of orifice diameter, orifice spacing, effective duct height, flameholder momentum flux ratio, vertical distance, and downstream distance was developed from the analyses of the non-reacting data. Concentrations of carbon dioxide, carbon monoxide, oxygen, unburned hydrocarbons, and nitric oxides were measured in a ramburner sector as a function of inlet temperature, inlet Mach number, air flow rate/area, equivalence ratio, and sampling probe location. Equations were developed that relate the combustion efficiency and the nitric oxides emission index to the reaction time and residence time.

Dynamics of Non-Premixed Bluff Body-Stabilized Flames in Heated Air Flow

2010 ◽  
Author(s):  
Caleb Cross ◽  
Aimee Fricker ◽  
Dmitriy Shcherbik ◽  
Eugene Lubarsky ◽  
Ben T. Zinn ◽  
...  
Keyword(s):  
Heat Release ◽  
Vortex Shedding ◽  
High Speed ◽  
Bluff Body ◽  
Combustion Process ◽  
Flame Stabilization ◽  
Inlet Temperature ◽  
Fuel Injectors ◽  
Flame Holder ◽  
Process Heat

This paper describes a study of the fundamental flame dynamic processes that control bluff body-stabilized combustion of liquid fuel with low dilatation. Specifically, flame oscillations due to asymmetric vortex shedding downstream of a bluff body (i.e., the Be´nard/von-Ka´rma´n vortex street) were characterized in an effort to identify the fundamental processes that most affect the intensity of these oscillations. For this purpose, the spatial and temporal distributions of the combustion process heat release were characterized over a range of inlet velocities, temperatures, and overall fuel-air ratios in a single flame holder combustion channel with full optical access to the flame. A stream of hot preheated air was supplied to the bluff body using a preburner, and Jet-A fuel was injected across the heated gas stream from discrete fuel injectors integrated within the bluff body. The relative amplitudes, frequencies, and phase of the sinusoidal flame oscillations were characterized by Fourier analysis of high-speed movies of the flame. The amplitudes of the flame oscillations were generally found to increase with global equivalence ratio, reaching a maximum just before rich blowout. Comparison of the flame dynamics to the time-averaged spatial heat release distribution revealed that the intensity of the vortex shedding decreased as a larger fraction of the combustion process heat release occurred in the shear layers surrounding the recirculation zone of the bluff body. Furthermore, a complete transition of the vortex shedding and consequent flame stabilization from asymmetric to symmetric modes was clearly observed when the inlet temperature was reduced from 850°C to 400°C (and hence, significantly increasing the flame dilatation ratio from Tb/Tu ∼ 2.3 to 3.7).

CFD Prediction and Design of Low NOx Radial Swirler Systems

2009 ◽  
Author(s):  
Phil T. King ◽  
Gordon E. Andrews ◽  
Myeong N. Kim ◽  
Mohamed Pourkashanian ◽  
Andy C. McIntosh
Keyword(s):  
Fuel Injection ◽  
Laminar Flame ◽  
Turbulent Flame ◽  
Inlet Temperature ◽  
Nox Emissions ◽  
Flamelet Model ◽  
Flame Thickness ◽  
Flame Development ◽  
Air Mixing ◽  
Dissipation Model

A radial swirler with vane passage fuel injection using a radial fuel spoke with one fuel hole per passage was investigated using CFD at 0.5 equivalence ratio and 600K inlet temperature at 1 bar. Experimental measurements of the internal flame composition from water cooled gas sample probes were the experimental results used for comparison. Three combustion models were compared: flamelet with two difference kinetic schemes; PDF transport with two step chemistry and finite rate eddy dissipation model. Both models consistently underpredicted the turbulent flame thickness to 90% heat release by a factor of about 2. The PDF model with postprocessing NOx predictions over estimated the NOx emissions considerably and the best model was the flamelet model with full chemistry. The under prediction of the turbulent reaction zone thickness was concluded to be due to inadequate modelling of strained flame quenching for very lean flames with large laminar flame thickness and very low burning velocities. This flamelet model was applied to predict the influence of the radial swirler outlet geometry on the flame development, fuel and air mixing and NOx emissions. A dump expansion from the radial swirler outlet was compared with the addition of a shroud at the outlet and with the addition of a 60mm long outlet throat. The shroud was shown to increase the peak turbulence and confine it very close to the shroud lip. This improved the fuel and air mixing and lowered the predicted NOx from 2.7ppm to 1.2ppm with the shrouded swirler and 0.3ppm with the 60mm outlet throat and mixing length.

Passive Control of Dynamic Pressures in a Dry, Low NOx Combustion System Using Fuel Gas Circuit Impedance Optimization

2005 ◽  
Author(s):  
Jeffrey Goldmeer ◽  
Simon Sanderson ◽  
Geoff Myers ◽  
Jesse Stewart ◽  
Michele D’Ercole
Keyword(s):  
Gas Turbine ◽  
Passive Control ◽  
Fuel Injection ◽  
Dynamic Pressure ◽  
Injection System ◽  
Fuel Gas ◽  
Lean Premixed Combustion ◽  
Fold Reduction ◽  
Low Nox Combustion ◽  
Original Laboratory

Dry, Low NOx (DLN) gas turbine combustion systems that use the lean, premixed combustion technique for emissions control are susceptible to dynamic pressure oscillations. During the initial full-load prototype testing of the MS5002E, excessive dynamic pressures were encountered when attempting fully premixed combustor operation, preventing the gas turbine from meeting a 15 ppm NOx emissions target. A series of experiments were performed to examine potential acoustic differences between the original laboratory fuel injection system and the prototype hardware used in the field test. The experimental results were used to validate an analytical model that was used to optimize the fuel circuit geometry for dynamics reduction. The resulting revised design demonstrated a ten-fold reduction in dynamic pressure amplitudes. As a result, the system was able to operate over the premixed mode operating range and provides the desired NOx levels with acceptable dynamic pressures and operability.

Co-Firing of Kerosene and Biodiesel With Natural Gas in a Low NOx Radial Swirl Combustor

2012 ◽  
Author(s):  
Mohamed A. Altaher ◽  
Hu Li ◽  
Gordon E. Andrews
Keyword(s):  
Natural Gas ◽  
Fuel Injection ◽  
Liquid Fuels ◽  
Inlet Temperature ◽  
Nox Emissions ◽  
Fuel Injector ◽  
Gas Combustion ◽  
Swirl Combustor ◽  
Low Nox Combustion ◽  
Natural Gas Combustion

Co-firing of biodiesel with natural gas, using a low NOx gas turbine combustor was investigated and compared with the equivalent natural gas and kerosene co-firing. The work was carried out at atmospheric pressure with 600K air inlet temperature and used an 8 vane radial swirler. Well mixed natural gas combustion was achieved using radially inward gas fuel injection through the wall of the swirler outlet throat. The biofuel was injected centrally using an eight hole radial fuel injector. This central fuel injector location forms a good pilot flame for natural gas low NOx combustion and was the only fuel injection location that biodiesel combustion could be stabilised. This was because central fuel injection was into the hot recirculating gases on the centreline that is a feature of radial swirl lean low NOX combustion. The biodiesel results were compared with equivalent tests for kerosene as the central injection fuel. Co-firing was investigated with a low level of main natural gas combustion that was held constant and the equivalence ratio was increased using the central injection of biodiesel or kerosene. Operation on kerosene with no acoustic problem was demonstrated up to Ø = 0.95. Three natural gas initial equivalence ratios were investigated with co-firing of liquid fuels, Ø = 0.18, 0.22 and 0.34. A key benefit of operating with hotter premixed combustion with natural gas was that the overall Ø at which stable low CO and HC operation could be achieved with biodiesel was extended to leaner overall Ø. The NOx emissions in this co-firing mode were remarkably low for relatively rich overall mixtures, where conventional single fuel main injection on natural gas gave higher NOx emissions.

Micro Mixing Fuel Injectors for Low Emissions Hydrogen Combustion

2008 ◽  
Author(s):  
Steven R. Hernandez ◽  
Qing Wang ◽  
Vincent McDonell ◽  
Adel Mansour ◽  
Erlendur Steinthorsson ◽  
...  
Keyword(s):  
Natural Gas ◽  
Gas Turbines ◽  
Fuel Injection ◽  
Turbine Engines ◽  
Nox Emissions ◽  
Gas Turbine Engines ◽  
Fuel Injectors ◽  
Air Mixing ◽  
Potential Benefits ◽  
Computational Fluid Dynamics Cfd

The consideration of hydrogen as a fuel for next generation low emissions gas turbines raises a number of challenges and potential benefits relative to the combustion system. The present work examines the use of a micro-mixing injection strategy for hydrogen as a means to achieve rapid mixing and inherent flexibility for accommodating various staging, dilution, and dual fuel requirements for future gas turbine engines. The work presented includes numerical and experimental results associated with the fuel-air mixing process in a representative injector configuration. Measured NOx emissions and fuel/air ratios at the exit of the mixer are shown along with visualization of the reactions generated. Detailed computational fluid dynamics (CFD) is used in parallel to elucidate the behavior of the flow inside and downstream of the injectors. Results are also presented for natural gas to provide a point of reference. The results illustrate a number of interesting features and characteristics of the hydrogen/air mixtures which are in dramatic contrast to the behavior of natural gas/air mixtures. Comparison of the measured and modeled mixing behavior illustrates a number of challenges associated with the selection of a robust modeling approach for hydrogen/air combustion. The results demonstrate that the use of micro-mixing fuel injection to achieve ultra low NOx emissions is very promising.

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