CFD Modeling of the Atomization of Plain Liquid Jets in Cross Flow for Gas Turbine Applications

2004 ◽  
Author(s):  
Sachin Khosla ◽  
D. Scott Crocker
Keyword(s):  
Momentum Flux ◽  
Drop Size ◽  
Fuel Injection ◽  
Cross Flow ◽  
Flux Ratio ◽  
Wake Flow ◽  
Cfd Modeling ◽  
Liquid Jets ◽  
Momentum Flux Ratio ◽  
Primary Breakup

A numerical model for liquid jet atomization in a subsonic gas cross flow has been developed and incorporated into a CFD code. The model is designed primarily for the shear breakup regime, which is appropriate for many fuel injection applications. The model considers Weber number and momentum flux ratio ranges that are dominated by either jet surface breakup or column breakup. A boundary layer stripping model has been modified to account for both shearing from the column and shear primary breakup of large drops. Further secondary breakup was modeled with the Rayleigh-Taylor model. The effect of drop distortion on the drag is also considered. Results of the model have been compared with experimental data for jet-A liquid jets in air cross flows with varying pressure, air velocity, and liquid-to-gas momentum flux ratio. Comparisons were made for drop volume flux and drop size as a function of distance from the injector wall. Trends were captured for liquid penetration associated with varying momentum flux ratio, and for drop size as a function distance from the wall. In general, agreement between measurements and CFD predictions were quite good. Areas of disagreement could be reasonably explained by the model’s inherent inability to capture the wake flow behind the liquid column.

scholarly journals Drop Size Characteristics of Forward Angled Injectors in Subsonic Cross Flows

2013 ◽  
Author(s):  
Venkat S. Iyengar ◽  
Sathiyamoorthy Kumarasamy ◽  
Srinivas Jangam ◽  
Manjunath Pulumathi
Keyword(s):  
Gas Turbine ◽  
Test Section ◽  
Momentum Flux ◽  
Drop Size ◽  
Cross Flow ◽  
Flux Ratio ◽  
Liquid Jet ◽  
Axial Distance ◽  
Momentum Flux Ratio ◽  
Spray Plume

Cross flow fuel injection is a widely used approach for injecting liquid fuel in gas turbine combustors and afterburners due to the higher penetration and rapid mixing of fuel and the cross flowing airstream. Because of the very limited residence time available in these combustors it is essential to ensure that smaller drop sizes are generated within a short axial distance from the injector in order to promote effective mixing. This requirement calls for detailed investigations into spray characteristics of different injector configurations in a cross-flow environment for identifying promising configurations. The drop size characteristics of a liquid jet issuing from a forward angled injector into a cross-flow of air were investigated experimentally at conditions relevant to gas turbine afterburners. A rig was designed and fabricated to investigate the injection of liquid jet in subsonic cross-flow with a rectangular test section of cross section measuring 50 mm by 70 mm. Experiments were done with a 10 degree forward angled 0.8 mm diameter plain orifice nozzle which was flush mounted on the bottom plate of test section. Laser diffraction using Malvern Spraytec particle analyzer was used to measure drops size and distributions in the near field of the spray. Measurements were performed at a distance of 70 mm from the injector at various locations along the height of the spray plume for a reasonable range of liquid flow rates as in practical devices. The sprays were characterized using the non dimensional parameters such as the Weber number and the momentum flux ratio and drop sizes were measured at three locations along the height of the spray from the bottom wall. The momentum flux ratio was varied from 5 to 25. Results indicate that with increase in momentum flux ratio the SMD reduced at the specific locations and an higher overall SMD was observed as one goes from the bottom to the top of the spray plume. This was accompanied by a narrowing of the drop size distribution.

Sprays in Cross Flow: Dependence on Weber Number

2007 ◽  
Author(s):  
Eugene Lubarsky ◽  
Jonathan R. Reichel ◽  
Ben T. Zinn ◽  
Rob McAmis
Keyword(s):  
Weber Number ◽  
Momentum Flux ◽  
Fuel Injection ◽  
Flow Direction ◽  
Air Flow ◽  
Cross Flow ◽  
Flux Ratio ◽  
Elevated Pressure ◽  
Momentum Flux Ratio ◽  
Breakup Mechanism

This paper describes an experimental investigation of the spray created by Jet A fuel injection from a plate containing sharp edged orifice 0.018 inches (457 μm) in diameter and L/D ratio of 10 into the crossflow of preheated air (555 K) at elevated pressure in the test section (4 ata) and liquid to air momentum-flux ratio of 40. A 2 component Phase Doppler Particle Analyzer used for measuring the characteristics of the spray. The Weber number of the spray in crossflow was varied between 33 and 2020 and the effect of Weber number on spray properties was investigated. It was seen that shear breakup mechanism dominates at Weber number greater than about 100. Droplets’ diameters were found to be in the range of 15-30 microns for higher values of Weber numbers, while larger droplets (100-200 microns) were observed at Weber number of 33. Larger droplets were observed at the periphery of the spray. The droplet velocities and diameters were measured in a plane 30mm downstream of the orifice along the centerline of the spray at an incoming air flow Mach number of 0.2 and liquid to air momentum-flux ratio of 40. The droplets reach a maximum of 90% of the flow velocity at this location. The velocity of droplets in the directions perpendicular to the air flow direction is higher at the periphery of the spray possibly due to the presence of larger droplets. The RMS values of the droplet velocities are highest slightly off center of the centerline of the spray showing the presence of strong vortices formed due to the liquid jet in crossflow. The data presented here could serve as benchmark data for CFD code validation.

Liquid Jets in Subsonic Air Crossflow at Elevated Pressure

2014 ◽  
Vol 137 (4) ◽  
Author(s):  
Jinkwan Song ◽  
Charles Cary Cain ◽  
Jong Guen Lee
Keyword(s):  
Weber Number ◽  
Momentum Flux ◽  
Drop Size ◽  
Density Ratio ◽  
Flux Ratio ◽  
Mie Scattering ◽  
Air Pressure ◽  
Scattering Intensity ◽  
Nozzle Orifice ◽  
Momentum Flux Ratio

The breakup, penetration, droplet size, and size distribution of a Jet A-1 fuel in air crossflow has been investigated with focus given to the impact of surrounding air pressure. Data have been collected by particle Doppler phased analyzer (PDPA), Mie-scattering with high speed photography augmented by laser sheet, and Mie-scattering with intensified charge-coupled device (ICCD) camera augmented by nanopulse lamp. Nozzle orifice diameter, do, was 0.508 mm and nozzle orifice length to diameter ratio, lo/do, was 5.5. Air crossflow velocities ranged from 29.57 to 137.15 m/s, air pressures from 2.07 to 9.65 bar, and temperature held constant at 294.26 K. Fuel flow provides a range of fuel/air momentum flux ratio (q) from 5 to 25 and Weber number from 250 to 1000. From the results, adjusted correlation of the mean drop size has been proposed using drop size data measured by PDPA as follows: (D0/D32)=0.267Wea0.44q0.08(ρl/ρa)0.30(μl/μa)-0.16. This correlation agrees well and shows roles of aerodynamic Weber number, Wea, momentum flux ratio, q, and density ratio, ρl/ρa. Change of the breakup regime map with respect to surrounding air pressure has been observed and revealed that the boundary between each breakup modes can be predicted by a transformed correlation obtained from above correlation. In addition, the spray trajectory for the maximum Mie-scattering intensity at each axial location downstream of injector is extracted from averaged Mie-scattering images. From these results, correlations with the relevant parameters including q, x/do, density ratio, viscosity ratio, and Weber number are made over a range of conditions. According to spray trajectory at the maximum Mie-scattering intensity, the effect of surrounding air pressure becomes more important in the farfield. On the other hand, effect of aerodynamic Weber number is more important in the nearfield.

Characterization of Spray Formed by Liquid Jet Injected Into Oscillating Air Crossflow

2015 ◽  
Author(s):  
Jinkwan Song ◽  
Jong Guen Lee
Keyword(s):  
Weber Number ◽  
Momentum Flux ◽  
Drop Size ◽  
Flux Ratio ◽  
Mie Scattering ◽  
Liquid Jet ◽  
Velocity Modulation ◽  
Momentum Flux Ratio ◽  
Crossflow Velocity ◽  
Modulation Level

This paper presents experimental results on the characteristics of spray formed by a liquid (Jet-A) jet injected into an oscillating air crossflow. Ambient air pressure is raised up to 15.86 bar, and the corresponding aerodynamic Weber number and liquid-air momentum flux ratio are up to 1000 and 25, respectively. The level of modulated crossflow velocity is kept up to 20% of its mean value. For limited cases, the air crossflow is preheated. Planar Mie-scattering measurements are utilized to visualize changes of the spray penetration and cross-sectional spray area in the oscillating air crossflow, and PDPA measurements are used to measure the mean drop size and drop size distribution. Phase-synchronized PDPA measurement of droplet size under the modulation of crossflow shows that the modulating crossflow results in preferentially larger amount of smaller and bigger droplets than average-sized droplets. Global spray response of spray to modulating crossflow is characterized by using proper orthogonal decomposition (POD) analysis of Mie-scattering images and collecting (and hence determining gain of) Mie-scattering intensity of droplets at a fixed downstream distance. It is found that the dominant behavior of the spray is convective oscillation in the axial direction and the change of vertical penetration of the spray is almost negligible for the level of crossflow velocity modulation up to 20%. The gain of Mie-scattering intensity with respect to crossflow velocity modulation level gradually decreases as liquid-air momentum flux ratio increases. Also, per given momentum flux ratio and Weber number, the gain hardly varies with respect to crossflow modulation level, suggesting the response of spray increases in proportion to crossflow velocity modulation level.

Computational Analysis on Primary Breakup and Deformation of Kerosene Jet in Subsonic Cross Flow Using VOF Method

2017 ◽  
Author(s):  
Muthuselvan Govindaraj ◽  
Muralidhara Halebidu Suryanarayanarao ◽  
Prateekkumar Kotegar ◽  
Sonali Gupta ◽  
Sanjay Shankar ◽  
...  
Keyword(s):  
Weber Number ◽  
Momentum Flux ◽  
Computational Analysis ◽  
Cross Flow ◽  
Flux Ratio ◽  
Experimental Results ◽  
Liquid Jet ◽  
Computational Domain ◽  
Breakup Process ◽  
Primary Breakup

The main objective of this computational analysis is to investigate the effect of increase in Weber number at constant momentum flux ratio on the primary breakup process and deformation of kerosene jet in cross stream air flow. Unsteady computational analysis with VOF approach is carried out to simulate the two phase flow at three different cross flow Weber number conditions (150, 350 and 400) at constant momentum flux ratio of 17. Since the results of VOF technique is highly sensitive to the size and distribution of grid, grid optimization process is carried out, with both structured and unstructured forms of the grid. Since the structured grid with number of elements 17,96,181 displayed better matching with experimental results of upper trajectory of kerosene jet; this grid is used to investigate the effect of turbulence model and Weber number on the windward trajectory of kerosene jet in cross flow air stream. Initially to evaluate the results of computational analysis; simulations are carried out with larger computational domain (with number of elements 17,96,181). Windward trajectory of computational analysis is compared with experimental results of upper trajectory predicted using image processing technique and reasonable overall matching is observed. To investigate the primary breakup process and deformation of liquid jet at three different increasing Weber number conditions, simulations are carried out with smaller computational domain with higher mesh density with number of elements 33,96,146. The computational technique used in the present analysis exactly captures the modes of breakup observed from experimental results at different Weber number operating conditions. To characterize the deformation of liquid jet at different Weber number conditions; near-field trajectory, cross stream dimension and wave length of liquid jet are quantified at different instants of time. With increase in Weber number, decrease in penetration of liquid jet along transverse direction and more bending of liquid jet along flow direction is observed. From the velocity profile along transverse direction of three different conditions, stronger shearing of liquid film is observed in higher Weber number conditions.

Investigation of Flow Characteristics in a Combustor With Opposed Jets

2018 ◽  
Author(s):  
Yongbin Ji ◽  
Bing Ge ◽  
Shusheng Zang
Keyword(s):  
Flow Field ◽  
Gas Turbine ◽  
Momentum Flux ◽  
Flow Characteristics ◽  
Cross Flow ◽  
Flux Ratio ◽  
Main Flow ◽  
3D Flow ◽  
Momentum Flux Ratio ◽  
High Efficient

Jet-in-cross flow (JICF) has been investigated broadly because of its wide engineering application, for example in the gas turbine field, film cooling on the turbine vanes and blades, primary and dilution jets in the combustors and so on. In the gas turbine combustors, the main flow is generated by the swirlers to stabilize the flame, which induces complicated 3D flow characteristics. Different from uniform main flow, swirling cross flow has a strong tangential velocity component, which will deflect the jets in the circumferential direction as well as in the streamwise direction. So, the degradation behavior of the jets is more complex than that in the uniform cross flow. This paper presents PIV measurement of the flow field inside of a three-nozzle annular combustor with opposed quenching jets on the liner walls. Dry ice as a newly proposed flow tracer was proposed and tried. The momentum flux ratio and jet holes configuration are studied to evaluate their effects on the primary recirculation zone, downstream flow field. Finally, numerical simulation was also performed to reveal 3D flow characteristics as well as turbulent kinetic energy generation. The results show that momentum flux ratio has a dominant influence on flow characteristics in the combustor. Getting better understanding of jets behavior in the swirling cross flow helps optimization design of quenching or dilution holes geometry and arrangement for the gas turbine combustor, which turns to be very beneficial to the low-emission and high efficient combustor development.

Liquid Fuel Placement and Mixing of Generic Aeroengine Premix Module at Different Operating Conditions

2003 ◽  
Vol 125 (4) ◽  
pp. 901-908 ◽  
Author(s):  
J. Becker ◽  
C. Hassa
Keyword(s):  
Momentum Flux ◽  
Liquid Fuel ◽  
Fuel Injection ◽  
Measurement Techniques ◽  
Flux Ratio ◽  
Mie Scattering ◽  
Operating Conditions ◽  
Operating Pressure ◽  
Flow Measurements ◽  
Momentum Flux Ratio

Fuel placement and air-fuel mixing in a generic aeroengine premix module employing plain jet liquid fuel injection into a counter-swirling double-annular crossflow were investigated at different values of air inlet pressure (6 bar, 700 K and 12 bar, 700 K) and liquid-to-air momentum flux ratio, both parameters being a function of engine power. Kerosene Jet A-1 was used as liquid fuel. Measurement techniques included LDA for investigation of the airflow and Mie-scattering laser light sheets and PDA for investigation of the two-phase flow. Measurements were taken at various axial distances from the fuel nozzle equivalent to mean residence times of up to 0.47 ms. It was found that the initial fuel placement reacts very sensitively to a variation of liquid-to-air momentum flux ratio. Susceptibility of the spray to dispersion due to centrifugal forces and to turbulent mixing is primarily a function of the fuel droplet diameters, which in turn depend on operating pressure. The data are interpreted by evaluation of the corresponding Stokes numbers.

Pulsation in Bag Breakup of Round Liquid Jets in Crossflow

2014 ◽  
Vol 1070-1072 ◽  
pp. 1945-1950
Author(s):  
Pei Feng Liu ◽  
Yong Huang ◽  
Zhi Lin Liu ◽  
Lei Sun
Keyword(s):  
Momentum Flux ◽  
High Speed ◽  
Gas Flow ◽  
Tap Water ◽  
Flux Ratio ◽  
Liquid Jets ◽  
High Speed Camera ◽  
Breakup Process ◽  
Test Liquid ◽  
Momentum Flux Ratio

An experiment was conducted to investigate bag breakup process of round liquid jets in crossflow. The objective of this study is to research pulsation law. Specifically, this study measures the onset position of bag, the breakup position of bag, the breakup position of the jet. High-speed camera was used to observe the formation and breakup of bags. The diameter of the nozzle used in the experiment was 0.5mm, 0.8mm, 1mm. The test liquid was tap water. Wea number covers the range of 6~30, and liquid-to-air momentum flux ratio varied from 22 to 211. Present results indicate that in the direction perpendicular to the gas flow, the dimensionless pulsating amount of the onset point of bags (yonset/d) is linear to q, while the dimensionless pulsating amount of breakup point of bags (ybag/d) and the dimensionless pulsating amount of breakup point of the jet (yjet/d) is linear to ln (q). The dimensionless pulsating amount of these points in the direction of gas flow is irregular.

Liquid Fuel Placement and Mixing of a Generic Aeroengine Premix Module at Different Operating Conditions

2002 ◽  
Author(s):  
Julian Becker ◽  
Christoph Hassa
Keyword(s):  
Momentum Flux ◽  
Liquid Fuel ◽  
Fuel Injection ◽  
Measurement Techniques ◽  
Flux Ratio ◽  
Mie Scattering ◽  
Operating Conditions ◽  
Operating Pressure ◽  
Flow Measurements ◽  
Momentum Flux Ratio

Fuel placement and air-fuel mixing in a generic aeroengine premix module employing plain jet liquid fuel injection into a counter-swirling double-annular crossflow were investigated at different values of air inlet pressure (6 bar, 700 K and 12 bar, 700 K) and liquid-to-air momentum flux ratio, both parameters being a function of engine power. Kerosene Jet A-1 was used as liquid fuel. Measurement techniques included LDA for investigation of the airflow and Mie-scattering laser light sheets and PDA for investigation of the two-phase flow. Measurements were taken at various axial distances from the fuel nozzle equivalent to mean residence times of up to 0.47 ms. It was found that the initial fuel placement reacts very sensitively to a variation of liquid-to-air momentum flux ratio. Susceptibility of the spray to dispersion due to centrifugal forces and to turbulent mixing is primarily a function of the fuel droplet diameters, which in turn depend on operating pressure. The data are interpreted by evaluation of the corresponding Stokes numbers.

Flow and Thermal Structure of Burner-Wake Stabilized Elliptic Jet Flames in a Cross-Flow

2005 ◽  
Author(s):  
S. R. Gollahalli
Keyword(s):  
Momentum Flux ◽  
Thermal Structure ◽  
Flame Structure ◽  
Cross Flow ◽  
Flux Ratio ◽  
Major Axis ◽  
Minor Axis ◽  
Jet Flames ◽  
Zone Structure ◽  
Momentum Flux Ratio

This study was conducted to delineate the coupling effects of the elliptic geometry of the burner and a crossflow on the combustion of gas jets. This paper presents the flow and thermal structure of burner-wake stabilized turbulent propane jet flames from circular (diameter = 0.45 cm) and elliptic (major axis/minor axis = 3) burners of equivalent exit area in a crossflow of air. The elliptic burner was oriented with its major axis or minor axis aligned with the crossflow. Experiments were conducted in a wind tunnel provided with optical and probe access. Flame structure data including temperature profiles and concentration profiles of CO2, O2, CO, and NO were obtained in the single flame configuration (at jet to crossflow momentum flux ratio = 0.0067), where a planar recirculation zone exists completely stabilized in the wake of the burner tube. This study is complementary to our previous study with a two-zone structure flame at jet/crossflow momentum flux ratio of 0.11. Results show that in this flame configuration, the peak NO concentration in the circular burner is higher than that in the elliptic burner flames. Carbon monoxide concentration was approximately same in the flame with circular burner and the elliptic burner with its major axis aligned with cross-flow; the CO concentration in the elliptic flame with the minor axis of the burner aligned with cross-flow was slightly smaller.

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