Preliminary Study of Low Emission Gas Turbine Combustor With Airblast Fuel Atomizer

1976 ◽  
Vol 98 (1) ◽  
pp. 15-22
Author(s):  
K. Yamanaka ◽  
K. Nagato
Keyword(s):  
Gas Turbine ◽  
Fuel Injection ◽  
Tube Wall ◽  
Combustion Stability ◽  
Exhaust Emission ◽  
Fuel Injector ◽  
Gas Turbine Combustor ◽  
Low Emission ◽  
New Type ◽  
Preliminary Study

Recent papers describe that an airblast fuel atomizer is very effective for reducing emissions from a gas turbine and this type of fuel injector is being applied to practical engines. This paper deals with the new type of airblast fuel atomizer AFIT which comes from “Airblast Fuel Injection Tube” that makes fuel to break up into droplets by atomizing air at several small holes on the tube wall and fuel is well mixed with atomizing air instantly at the exits of holes. Regarding this AFIT, the fuel spray characteristics, combustion stability which is usually narrow for the combustor with an airblast fuel atomizer at lower engine speeds and exhaust emission levels are experimented and its effectiveness is discussed.

Study of Flame Stability in a Step Swirl Combustor

1996 ◽  
Vol 118 (2) ◽  
pp. 308-315 ◽  
Author(s):  
M. D. Durbin ◽  
M. D. Vangsness ◽  
D. R. Ballal ◽  
V. R. Katta
Keyword(s):  
Gas Turbine ◽  
Recirculation Zone ◽  
Swirling Flow ◽  
Tangential Velocity ◽  
Combustion Stability ◽  
Combustion Model ◽  
Fuel Injector ◽  
Gas Turbine Combustor ◽  
Swirl Combustor ◽  
Radial Profiles

A prime requirement in the design of a modern gas turbine combustor is good combustion stability, especially near lean blowout (LBO), to ensure an adequate stability margin. For an aeroengine, combustor blow-off limits are encountered during low engine speeds at high altitudes over a range of flight Mach numbers. For an industrial combustor, requirements of ultralow NOx emissions coupled with high combustion efficiency demand operation at or close to LBO. In this investigation, a step swirl combustor (SSC) was designed to reproduce the swirling flow pattern present in the vicinity of the fuel injector located in the primary zone of a gas turbine combustor. Different flame shapes, structure, and location were observed and detailed experimental measurements and numerical computations were performed. It was found that certain combinations of outer and inner swirling air flows produce multiple attached flames, aflame with a single attached structure just above the fuel injection tube, and finally for higher inner swirl velocity, the flame lifts from the fuel tube and is stabilized by the inner recirculation zone. The observed difference in LBO between co- and counterswirl configurations is primarily a function of how the flame stabilizes, i.e., attached versus lifted. A turbulent combustion model correctly predicts the attached flame location(s), development of inner recirculation zone, a dimple-shaped flame structure, the flame lift-off height, and radial profiles of mean temperature, axial velocity, and tangential velocity at different axial locations. Finally, the significance and applications of anchored and lifted flames to combustor stability and LBO in practical gas turbine combustors are discussed.

Study of Flame Stability in a Step Swirl Combustor

1995 ◽  
Author(s):  
Mark D. Durbin ◽  
Marlin D. Vangsness ◽  
Dilip R. Ballal ◽  
Viswanath R. Katta
Keyword(s):  
Gas Turbine ◽  
Recirculation Zone ◽  
Swirling Flow ◽  
Tangential Velocity ◽  
Combustion Stability ◽  
Combustion Model ◽  
Fuel Injector ◽  
Gas Turbine Combustor ◽  
Swirl Combustor ◽  
Radial Profiles

A prime requirement in the design of a modem gas turbine combustor is good combustion stability, especially near lean blowout (LBO), to ensure an adequate stability margin. For an aeroengine, combustor blow-off limits are encountered during low engine speeds at high altitudes over a range of flight Mach numbers. For an industrial combustor, requirements of ultra-low NOx emissions coupled with high combustion efficiency demand operation at or close to LBO. In this investigation, a step swirl combustor (SSC) was designed to reproduce the swirling flow pattern present in the vicinity of the fuel injector located in the primary zone of a gas turbine combustor. Different flame shapes, structure and location were observed and detailed experimental measurements and numerical computations were performed. It was found that certain combinations of outer and inner swirling air flows produce multiple attached flames, a flame with a single attached structure just above the fuel injection tube, and finally for higher inner swirl velocity, the flame lifts from the fuel tube and is stabilized by the inner recirculation zone. The observed difference in LBO between co- and counter-swirl configurations is primarily a function of how the flame stabilizes i.e., attached vs. lifted. A turbulent combustion model correctly predicts the attached flame location(s), development of inner recirculation zone, a dimple-shaped flame structure, the flame lift-off height, and radial profiles of mean temperature, axial velocity, and tangential velocity at different axial locations. Finally, the significance and applications of anchored and lifted flames to combustor stability and LBO in practical gas turbine combustors are discussed.

Experimental Investigation of Spray and Combustion Performances of a Fuel-Staged Low Emission Combustor: Part II — Effects of Venturi Angle

2018 ◽  
Author(s):  
Cunxi Liu ◽  
Fuqiang Liu ◽  
Jinhu Yang ◽  
Yong Mu ◽  
Gang Xu
Keyword(s):  
Flow Field ◽  
High Altitude ◽  
Gas Turbines ◽  
Fuel Injection ◽  
Operating Conditions ◽  
Combustion Stability ◽  
Main Stage ◽  
Fuel Injector ◽  
Lean Burn ◽  
Low Emission

In order to reduce NOx emissions, modern gas turbines are often equipped with lean burn combustion systems, where the high-velocity fuel-lean conditions that limit NOx formation in combustors also inhibit the ability of ignition, high altitude relight, and lean combustion stability. To face these issues, an internally staged scheme of fuel injection is proposed. The pilot and main fuel staging enable fuel distribution control and high turn-down ratio, multi-injections of main fuel leads to a fast and efficient fuel/air mixing. A fuel-staged low emission combustor in the framework of lean burn combustion is developed in the present study, the central pilot stage of fuel injector working singly at low power operating conditions is swirl-cup prefilming atomization and main stage is jet-in-crossflow multi-injection atomization, a combination of pilot and main stage injection is provided for higher power operating conditions. A significant amount of the air mass flow utilised for fuel preparation and initiation is adverse to the operability specifications, such as ignition, lean blow-out, and high-altitude relight etc. The spray characteristics of pilot spray and flow field are one of the key factors affecting combustion operability. This work investigates the effects of the venturi angle on combustion operability, the ignition and lean blow-out performances were evaluated in a single dome rectangular combustor. Furthermore, the spray patterns and flow field are characterized by kerosene-planar laser induced fluorescence and particle image velocimetry to provide insight into the correlation between spray, flow field and combustion operability performances.

Experimental Evaluation of Fuel Injection Configurations for a Lean-Premixed Low NOx Gas Turbine Combustor

1987 ◽  
Author(s):  
Kenneth O. Smith ◽  
F. R. Kurzynske ◽  
Leonard C. Angello
Keyword(s):  
Gas Turbine ◽  
Experimental Evaluation ◽  
Fuel Injection ◽  
Nox Emissions ◽  
Fuel Injector ◽  
Gas Turbine Combustor ◽  
Program Goal ◽  
Preliminary Step ◽  
Gas Fuel ◽  
Design And Testing

The design and testing of three natural gas fuel injector configurations for a low emissions gas turbine combustor are described. The injectors provided varying degrees of fuel/air premixing and permitted an assessment of the degree of premixing necessary to achieve NOx emissions below the program goal of 10 ppm. The work described represents a preliminary step in an effort to develop production-level gas turbine combustor hardware with ultra-low NOx capabilities.

An Experimental Study on the Coupling of Combustion Instability Mechanisms in a Lean Premixed Gas Turbine Combustor

2009 ◽  
Author(s):  
Hyung Ju Lee ◽  
Kyu Tae Kim ◽  
Jong Guen Lee ◽  
Bryan D. Quay ◽  
Domenic A. Santavicca
Keyword(s):  
Experimental Study ◽  
Gas Turbine ◽  
Equivalence Ratio ◽  
Acoustic Pressure ◽  
Fuel Injection ◽  
Operating Conditions ◽  
Fuel Injector ◽  
Gas Turbine Combustor ◽  
Lean Premixed ◽  
Injection Location

An experimental study was conducted to characterize the combined effects of flame-vortex interactions and equivalence ratio fluctuations on self-excited combustion instabilities in a swirl-stabilized lean premixed gas turbine combustor. The combustor was designed so that the fuel injector location and the combustion chamber length could be independently varied. In addition, the fuel and air could be mixed upstream of the choked inlet to the combustor, thereby eliminating the possibility of equivalence ratio fluctuations. Experiments were performed over a broad range of operating conditions and at each condition both the combustor length and the fuel injection location were varied. Dynamic pressure in the combustor, acoustic pressure and velocity in the mixing section, and the overall rate of heat release were simultaneously measured at all operating conditions. Two distinct instability regimes were observed; one near 220 Hz and the other near 345 Hz. It was also found that the strength of the instability changed significantly as the fuel injection location was varied, while the phase of the acoustic pressure and velocity fluctuations in the mixing section did not change. A time series of pressure and CH* chemiluminescence signals confirmed constructive or destructive coupling of the two instability mechanisms; the flame-vortex interaction and the equivalence ratio fluctuation interact each other and determine the instability characteristics in partially premixed conditions.

Modeling of Gas Turbine Fuel Nozzle Spray

1997 ◽  
Vol 119 (1) ◽  
pp. 34-44 ◽  
Author(s):  
N. K. Rizk ◽  
J. S. Chin ◽  
M. K. Razdan
Keyword(s):  
Gas Turbine ◽  
Fuel Injection ◽  
Near Field ◽  
Continuous Phase ◽  
Liquid Sheet ◽  
Vapor Concentration ◽  
Fuel Vapor ◽  
Fuel Injector ◽  
Gas Temperature ◽  
Sheet Breakup

Satisfactory performance of the gas turbine combustor relies on the careful design of various components, particularly the fuel injector. It is, therefore, essential to establish a fundamental basis for fuel injection modeling that involves various atomization processes. A two-dimensional fuel injection model has been formulated to simulate the airflow within and downstream of the atomizer and address the formation and breakup of the liquid sheet formed at the atomizer exit. The sheet breakup under the effects of airblast, fuel pressure, or the combined atomization mode of the airassist type is considered in the calculation. The model accounts for secondary breakup of drops and the stochastic Lagrangian treatment of spray. The calculation of spray evaporation addresses both droplet heat-up and steady-state mechanisms, and fuel vapor concentration is based on the partial pressure concept. An enhanced evaporation model has been developed that accounts for multicomponent, finite mass diffusivity and conductivity effects, and addresses near-critical evaporation. The presents investigation involved predictions of flow and spray characteristics of two distinctively different fuel atomizers under both nonreacting and reacting conditions. The predictions of the continuous phase velocity components and the spray mean drop sizes agree well with the detailed measurements obtained for the two atomizers, which indicates the model accounts for key aspects of atomization. The model also provides insight into ligament formation and breakup at the atomizer exit and the initial drop sizes formed in the atomizer near field region where measurements are difficult to obtain. The calculations of the reacting spray show the fuel-rich region occupied most of the spray volume with two-peak radial gas temperature profiles. The results also provided local concentrations of unburned hydrocarbon (UHC) and carbon monoxide (CO) in atomizer flowfield, information that could support the effort to reduce emission levels of gas turbine combustors.

Experimental Assessment of the Emissions Benefits of a Ceramic Gas Turbine Combustor

1996 ◽  
Author(s):  
K. O. Smith ◽  
A. Fahme
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Flow Distribution ◽  
Operating Conditions ◽  
Nox Emissions ◽  
Fuel Injector ◽  
Gas Turbine Combustor ◽  
Experimental Assessment ◽  
Industrial Gas Turbine ◽  
Combustor Liner

Three subscale, cylindrical combustors were rig tested on natural gas at typical industrial gas turbine operating conditions. The intent of the testing was to determine the effect of combustor liner cooling on NOx and CO emissions. In order of decreasing liner cooling, a metal louvre-cooled combustor, a metal effusion-cooled combustor, and a backside-cooled ceramic (CFCC) combustor were evaluated. The three combustors were tested using the same lean-premixed fuel injector. Testing showed that reduced liner cooling produced lower CO emissions as reaction quenching near the liner wall was reduced. A reduction in CO emissions allows a reoptimization of the combustor air flow distribution to yield lower NOx emissions.

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