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.

Modeling of Gas Turbine Fuel Nozzle Spray

1995 ◽  
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 2-D 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 air-assist 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 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 present 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.

Post Fuel Injection Fuel Vaporization Characteristics in the Intake Port of a Port-Fuel-Injected Gasoline CFR Engine

2006 ◽  
Author(s):  
Jim S. Cowart ◽  
Leonard J. Hamilton
Keyword(s):  
Gasoline Engine ◽  
Fuel Injection ◽  
Fuel Vapor ◽  
Intake Port ◽  
Fuel Injector ◽  
Intake Valve ◽  
Inlet Port ◽  
Fuel Vaporization ◽  
Control Computer ◽  
Vapor Sampling

A Cooperative Fuels Research (CFR) gasoline engine has been modified to run on computer controlled Port Fuel Injection (PFI) and electronic ignition. Additionally a fast acting sampling valve (controlled by the engine control computer) has been placed in the engine’s intake system between the fuel injector and cylinder head in order to measure the fuel components that are vaporizing in the intake port immediately after the fuel injection event, and separately during the intake valve open period. This is accomplished by fast sampling a small portion of the intake port gases during a specified portion of the engine cycle which are then analyzed with a gas chromatograph. Experimental mixture preparation results as a function of inlet port temperature and pressure are presented. As the inlet port operates at higher temperatures and lower manifold pressures more of the injected fuels’ heavier components evolve into the vapor form immediately after fuel injection. The post-fuel injection fuel-air equivalence ratio in the intake port is characterized. The role of the fuel injection event is to produce from 1/4 to slightly over 1/2 of the combustible fuel-air mixture needed by the engine, as a function of port temperature. Fuel vapor sampling during the intake valve open period suggests that very little fuel is vaporizing from the intake port puddle below the fuel injector. In-cylinder fuel vapor sampling shows that significant fuel vapor generation must occur in the lower intake port and intake valve region.

Flame Holding in the Premixing Zone of a Gas Turbine Model Combustor After Forced Ignition of H2-NG-Air-Mixtures

2016 ◽  
Author(s):  
Matthias Utschick ◽  
Thomas Sattelmayer
Keyword(s):  
Gas Turbine ◽  
Atmospheric Pressure ◽  
Gas Turbines ◽  
Fuel Injection ◽  
Air Flow ◽  
Fuel Injector ◽  
Safe Operation ◽  
Trailing Edge ◽  
Damage And Failure ◽  
Turbine Model

Flashback and self-ignition in the premixing zone of typical gas turbine swirl combustors in lean premixed operation are immanent risks and can lead to damage and failure of components. Thus, steady combustion in the premixing zone must be avoided under all circumstances. This study experimentally investigates the flame holding propensity of fuel injectors in the swirler of a gas turbine model combustor with premixing of H2-NG-air-mixtures under atmospheric pressure and proposes a model to predict the limit for safe operation. The A2EV swirler concept exhibits a hollow, thick walled conical structure with four tangential slots. Four fuel injector geometries were tested. One of them injects the fuel orthogonal to the air flow in the slots (jet-in-crossflow-injector, JICI). Three injector types introduce the fuel almost isokinetic to the air flow at the trailing edge of the swirler slots (trailing edge injector, TEI). A cylindrical duct and a window in the swirler made of quartz glass allow the application of optical diagnostics (OH* chemiluminescence and Planar Laser Induced Fluorescence of the OH radical (OH-PLIF)) inside the swirler. The fuel-air-mixture was ignited with a focused single laser pulse during steady operation. The position of ignition was located inside the swirler in proximity to a fuel injection hole. If the flame was washed out of the premixing zone not later than four seconds after the ignition the operation point was defined as safe. Operation points were investigated at three air mass flows, three air ratios, two air preheat temperatures (573 K, 673 K) and 40 to 100 percent per volume hydrogen in the fuel composed of hydrogen and natural gas. The determined safety limit for atmospheric pressure yields a similarity rule based on a critical Damköhler number. Application of the proposed rule at conditions typical for gas turbines leads to these safety limits for the A2EV burner: With the TEIs the swirler can safely operate with up to 80 percent per volume hydrogen content in the fuel at an air ratio of two. With the JIC injector safe operation at stoichiometric conditions and 95 percent per volume hydrogen is possible.

scholarly journals Longitudinal instabilities in an air-blasted liquid sheet

2001 ◽  
Vol 437 ◽  
pp. 143-173 ◽  
Author(s):  
ANTONIO LOZANO ◽  
FÉLIX BARRERAS ◽  
GUILLERMO HAUKE ◽  
CÉSAR DOPAZO
Keyword(s):  
Boundary Layer ◽  
Oscillation Frequency ◽  
Numerical Study ◽  
Near Field ◽  
Interface Velocity ◽  
Liquid Sheet ◽  
Linear Instability ◽  
Air Velocity ◽  
Instability Analysis ◽  
Sheet Breakup

An experimental and numerical study has been performed to improve the understanding of the air/liquid interaction in an air-blasted breaking water sheet. This research is focused in the near field close to the exit slit, because it is in this region where instabilities develop and grow, leading to the sheet breakup. In the experiments, several relevant parameters were measured including the sheet oscillation frequency and wavelength, as well as the droplet size distribution and the amplification growth rate. The flow was also investigated using linear instability theory. In the context of existing papers on instability analysis, the numerical part of this work presents two unique features. First, the air boundary layer is taken into account, and the effects of air and liquid viscosity are revealed. Second, the equations are solved for the same parameter values as those in the experiments, enabling a direct comparison between calculations and measurements; although qualitatively the behaviour of the measured variables is properly described, quantitative agreement is not satisfactory. Limitations of the instability analysis in describing this problem are discussed. From all the collected data, it is confirmed that the oscillation frequency strongly depends on the air speed due to the near-nozzle air/water interaction. The wave propagates with accelerating interface velocity which in our study ranges between the velocity of the water and twice that value, depending on the air velocity. For a fixed water velocity, the oscillation frequency varies linearly with the air velocity. This behaviour can only be explained if the air boundary layer is considered.

scholarly journals Optical Characterization of a Multipoint Lean Direct Injector for Gas Turbine Combustors: Velocity and Fuel Drop Size Measurements

2010 ◽  
Author(s):  
Christopher M. Heath ◽  
Yolanda R. Hicks ◽  
Robert C. Anderson ◽  
Randy J. Locke
Keyword(s):  
Gas Turbine ◽  
Drop Size ◽  
Fuel Injection ◽  
Direct Injection ◽  
Operating Conditions ◽  
Diagnostic Methods ◽  
Spray Angle ◽  
Fuel Injector ◽  
Flame Tube ◽  
Component Velocity

Performance of a multipoint, lean direct injection (MP-LDI) strategy for low emission aero-propulsion systems has been tested in a Jet-A fueled, lean flame tube combustion rig. Operating conditions for the series of tests included inlet air temperatures between 672 K and 828 K, pressures between 1034 kPa and 1379 kPa and total equivalence ratios between 0.41 and 0.45, resulting in equilibrium flame temperatures approaching 1800 K. Ranges of operation were selected to represent the spectrum of subsonic and supersonic flight conditions projected for the next-generation of commercial aircraft. This document reports laser-based measurements of in situ fuel velocities and fuel drop sizes for the NASA 9-point LDI hardware arranged in a 3 × 3 square grid configuration. Data obtained represent a region of the flame tube combustor with optical access that extends 38.1-mm downstream of the fuel injection site. All data were obtained within reacting flows, without particle seeding. Two diagnostic methods were employed to evaluate the resulting flow path. Three-component velocity fields have been captured using phase Doppler interferometry (PDI), and two-component velocity distributions using planar particle image velocimetry (PIV). Data from these techniques have also offered insight into fuel drop size and distribution, fuel injector spray angle and pattern, turbulence intensity, degree of vaporization and extent of reaction. This research serves to characterize operation of the baseline NASA 9-point LDI strategy for potential use in future gas-turbine combustor applications. An additional motive is the compilation of a comprehensive database to facilitate understanding of combustor fuel injector aerodynamics and fuel vaporization processes, which in turn may be used to validate computational fluid dynamics codes, such as the National Combustor Code (NCC), among others.

scholarly journals Observations of Flame Behavior From a Practical Fuel Injector Using Gaseous Fuel in a Technology Combustor

1994 ◽  
Author(s):  
Paul O. Hedman ◽  
Geoffrey J. Sturgess ◽  
David L. Warren ◽  
Larry P. Goss ◽  
Dale T. Shouse
Keyword(s):  
Gas Turbine ◽  
Air Force ◽  
Diffusion Flames ◽  
Fuel Injector ◽  
Gas Temperature ◽  
Brigham Young University ◽  
Lean Blowout ◽  
Reaction Zones ◽  
Air Force Base ◽  
Whitney Aircraft

This paper presents results from an Air Force program being conducted by researchers at Brigham Young University (BYU) Wright-Patterson Air Force Base (WPAFB), and Pratt and Whitney Aircraft Co (P&W). This study is part of a comprehensive effort being supported by the Aero Propulsion and Power Laboratory at Wright-Patterson Air Force Base, and Pratt and Whitney Aircraft, Inc. in which simple and complex diffusion flames are being studied to better understand the fundamentals of gas turbine combustion near lean blowout. The program’s long term goal is to improve the design methodology of gas turbine combustors. This paper focuses on four areas of investigation: 1) digitized images from still film photographs to document the observed flame structures as fuel equivalence ratio was varied, 2) sets of LDA data to quantify the velocity flow fields existing in the burner, 3) CARS measurements of gas temperature to determine the temperature field in the combustion zone, and to evaluate the magnitude of peak temperature, and 4) two-dimensional images of OH radical concentrations using PLIF to document the instantaneous location of the flame reaction zones.

Investigation on Mixing Characteristics of Methane Fuel in Low Emission Combustor

2020 ◽  
Author(s):  
Enhui Liu ◽  
Xiao Liu ◽  
Hongtao Zheng ◽  
Jinghe Lu ◽  
Zhihao Zhang ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Recirculation Zone ◽  
Fuel Injection ◽  
Near Field ◽  
Velocity Ratio ◽  
Pollutant Emission ◽  
Windward Side ◽  
Leeward Side ◽  
Low Emission ◽  
Mixing Characteristics

Abstract With the increasingly environmental problems and strict pollutant emission limits, pollutant emission has become a critical consideration for gas turbine. Mixing uniformity index of fuel-air has a significant effect on NOx emission. Previous works conducted basic research on mixing mechanism based on jet in crossflow, while few people studied a single real swirler channel in gas turbine combustor. The present work aims to bridge this gap and investigates the effects of fuel injection from the windward and leeward sides on the fuel concentration distribution and mixing uniformity index, based on a typical radical swirler channel. The qualitative analysis of velocity field and vortices structure and the quantitative analysis of velocity ratio and uniformity index are carried out. Due to the presence of sharp corner at the inlet of swirler, a recirculation zone is formed by the flow separation. The recirculation zone at the leeward side decreases the flow velocity and increases the area and time for fuel-air mixing. The velocity ratio plays a key role in the characteristics of flow and mixing. Under the same inlet conditions, the effective velocity ratio (R = 40) in the near field of the leeward side is about 10 times that of windward side (R = 4), and the maximum jet depth can be achieved in the near field. Therefore, the outlet uniformity index on the windward and leeward sides are 38.85% and 49.43%, respectively. From the perspective of mixing uniformity, fuel injection from the leeward side is beneficial to realize quick mixing in short distance. The present study is expected to provide insightful information for understanding mixing characteristics of methane fuel in low emission combustor.

Parametric Study to Optimize Air/Fuel Mixing for Lean, Premix Combustion Systems

2002 ◽  
Author(s):  
Ibrahim Yimer ◽  
Ian Campbell
Keyword(s):  
Gas Turbine ◽  
Fuel Injection ◽  
Fuel Mixture ◽  
Statistical Technique ◽  
Gas Temperature ◽  
Physical Processes ◽  
Mixture Preparation ◽  
Premix Combustion ◽  
Planar Laser ◽  
Set Up

New designs of gas turbine combustors for power generation applications have to meet ever-tightening emission standards (mainly NOx, CO and UHC) while operating at high combustor pressures. This requires a detailed understanding of the physical processes involved. The air-fuel mixture preparation is a critical step in most advanced gas turbine combustion strategies to achieve lower emissions. It has long been established that the level of unmixedness between the fuel and air is strongly tied with NOx levels. The present paper applies the statistical technique of Design Of Experiments (DOE) to a generic mixer set-up that includes an axial swirler, with fuel injected at discrete locations and transverse to the flow. The objective is to identify influential design and operating parameters that will provide rapid and enhanced mixing. The parameters tested include Swirl strength as measured by the Swirl number, Swirl type (Constant angle vs. Free vortex), number and momentum of fuel injection sites and gas temperature. Planar Laser Induced Fluorescence of acetone (PLIF) was used to quantify mixing at various planar locations in the mixing section. Commercial CFD software is used to model the flow field and predict the spatial mixing at selected conditions. Comparisons are made with experimental measurements with the aim to validate the CFD code and also on comparing the model results with the measurements.

Insertion of Electrostatically Charged Fuel Atomization Technology Into a U.S. Navy Shipboard Gas Turbine Engine

2004 ◽  
Author(s):  
David P. Guimond ◽  
Matthew E. Thomas ◽  
Roberto DiSalvo ◽  
Adam Elliot ◽  
D. Scott Crocker
Keyword(s):  
Numerical Modeling ◽  
Gas Turbine ◽  
System Integration ◽  
Gas Turbines ◽  
Fuel Injection ◽  
Research Effort ◽  
Injection System ◽  
Particulate Emissions ◽  
Fuel Injector ◽  
Electrostatic Charging

Recent breakthroughs in the field of hydrocarbon fuel electrostatic charging techniques have now permitted the opportunity for the Navy to consider implementing this technology into shipboard gas turbines. This research effort is focused toward electrostatic atomization insertion into a U.S. Navy Shipboard Rolls Royce Corporation 501-K research engine at the Naval Surface Warfare Center, Carderock Division (NSWCCD). Specific milestones achieved thus far include: (a) Spray demonstration of an electrostatically boosted 501-K gas turbine fuel injector prototype at fuel flows from 40 PPH to 250 PPH. (b) Electrostatic charging effect measurements on the droplet size and patternation of a 501-K simplex atomizer configuration. (c) Numerical modeling of the influence electrostatic charging has on secondary atomization breakup and predicted particulate emissions. This paper documents results associated with injector conceptual design, electrode integration, atomization measurements, numerical modeling and fuel injection system integration. Preliminary results indicate electrostatic boosting may be capable of reducing particulate emissions up to 80% by inserting the appropriate fuel injector.

Development of a Dual Fuel LBTU Gas/Diesel Burning Combustion System for a 4.2 MW Gas Turbine

1994 ◽  
Author(s):  
A. F. Al-Shaikhly ◽  
T. I. Mina ◽  
M. O. Neergaard
Keyword(s):  
Gas Turbine ◽  
Diesel Fuel ◽  
Fuel Injection ◽  
Stability Margin ◽  
Combined Cycle ◽  
Dual Fuel ◽  
Combustion System ◽  
Fuel Injector ◽  
Integrated Gasification Combined Cycle ◽  
Exhaust Temperature

This paper describes the design and development of a gas turbine combustion system (combustion chamber and dual fuel injector) that is capable of burning a gasifier generated low heating value (LBTU) gas as well as a conventional gas turbine (diesel) fuel. The system will be installed in a 4.2 MW gas turbine and forms part of a 15 MW integrated gasification combined cycle heat and power generation technology demonstrator plant in Sweden. The combustion system design features a conventional combustor air distribution and aerodynamic pattern, discrete coaxial jets air blast liquid fuel atomisation and a combination of swirl and plain orifice LBTU gas fuel injection with a passive air purge arrangement. Rig tests were carried out at operating pressures of up to 7 bar simulating various engine operating points using LBTU gas and diesel fuel. The results showed that the emissions, exhaust temperature distribution and combustor metal temperature were in line with the program objectives. The lean flame stability margin using LBTU gas was more than adequate in relation to load change and fuel changeover requirements.

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