Drop Size Characteristics of Forward Angled Injectors in Subsonic Cross Flows

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.

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

Volume 4B: Combustion, Fuels and Emissions ◽

10.1115/gt2015-43726 ◽

2015 ◽

Cited By ~ 1

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.

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Investigation of Flow Characteristics in a Combustor With Opposed Jets

Volume 4B: Combustion, Fuels, and Emissions ◽

10.1115/gt2018-76278 ◽

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.

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Trajectory of a Liquid Jet in a High Temperature and Pressure Gaseous Cross Flow

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.4042817 ◽

2019 ◽

Vol 141 (6) ◽

Cited By ~ 2

Author(s):

Amirreza Amighi ◽

Nasser Ashgriz

Keyword(s):

Momentum Flux ◽

Cross Flow ◽

Flux Ratio ◽

Liquid Jet ◽

Momentum Flux Ratio ◽

Flow Parameters ◽

System A ◽

Air Temperatures ◽

Jet Trajectory ◽

Temperature And Pressure

An experimental study of liquid jet injection into subsonic air crossflow is presented. The aim of this study was to relate the jet trajectory to flow parameters, including jet and air velocities, pressure and temperature, as well as a set of nondimensional variables. For this purpose, an experimental setup was developed, which could withstand high temperatures and pressures. Images were captured using a laser-based shadowgraphy system. A total of 209 different conditions were tested and over 72,000 images were captured and processed. The crossflow air temperatures were 25 °C, 200 °C, and 300 °C; absolute crossflow air pressures were 2.1, 3.8, and 5.2 bars, and various liquid and gas velocities were tested for each given temperature and pressure. The results indicate that the trajectory and atomization change when the air and jet velocities are changed while keeping the momentum flux ratio constant. Therefore, it is beneficial to describe the trajectory based on air and jet Weber numbers or momentum flux ratio in combination with one of the Weber numbers. Also, examples are given where both Weber numbers are kept constant but the atomization is changed, and therefore, other terms beyond inertia terms are required to describe the spray behavior. It is also shown that the gas viscosity has to be considered when developing correlations. The correlations that include this term are generally better in predicting the trajectory. Therefore, Ohnesorge numbers in combination with the Weber numbers is used in the present correlations to describe the trajectories.

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

Volume 1: Turbo Expo 2004 ◽

10.1115/gt2004-54269 ◽

2004 ◽

Cited By ~ 8

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.

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Liquid Jets in Subsonic Air Crossflow at Elevated Pressure

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.4028565 ◽

2014 ◽

Vol 137 (4) ◽

Cited By ~ 22

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.

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Effect of Cross-Flow Swirl on the Trajectory of Spray in an Annular Passage

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.4049378 ◽

2020 ◽

Author(s):

Tushar Sikroria ◽

Abhijit Kushari

Keyword(s):

Momentum Flux ◽

High Speed ◽

Air Flow ◽

Cross Flow ◽

Flux Ratio ◽

Liquid Jet ◽

Swirl Number ◽

Flow Swirl ◽

Air Stream ◽

The Impact

Abstract This paper presents the experimental analysis of the impact of swirl number of cross-flowing air stream on liquid jet spray trajectory at a fixed air flow velocity of 42 m/s with the corresponding Mach number of 0.12. The experiments were conducted for 4 different swirl numbers (0, 0.2, 0.42 and 0.73) using swirl vanes at air inlet having angles of 0°, 15°, 30° and 45° respectively. Liquid to air momentum flux ratio (q) was varied from 5 to 25. High speed (@ 500 fps) images of the spray were captured and those images were processed using MATLAB to obtain the path of the spray at various momentum flux ratios. The results show interesting trends for the spray trajectory and the jet spread in swirling air flow. High swirling flows not only lead to spray with lower radial penetration due to sharp bending and disintegration of liquid jet, but also result in spray with high jet spread and spray area. Based on the results, correlations for the spray path have been proposed which incorporates the effects of the swirl number of the air flow.

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Experimental Investigation of Liquid Jet Breakup in a Cross Flow of a Swirling Air Stream

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.4026244 ◽

2014 ◽

Vol 136 (6) ◽

Cited By ~ 4

Author(s):

Tushar Sikroria ◽

Abhijit Kushari ◽

Saadat Syed ◽

Jeffery A. Lovett

Keyword(s):

Experimental Investigation ◽

Momentum Flux ◽

High Speed ◽

Cross Flow ◽

Flux Ratio ◽

Liquid Jet ◽

Breakup Process ◽

Breakup Length ◽

Jet Breakup ◽

Penetration Behavior

This paper presents the results of an experimental investigation of liquid jet breakup in a cross flow of air under the influence of swirl (swirl numbers 0 and 0.2) at a fixed air flow Mach number 0.12 (typical gas turbine conditions). The experiments have been conducted for various liquid to air momentum flux ratios (q) in the range of 1 to 25. High speed (@ 500 fps) images of the jet breakup process are captured and those images are processed using matlab to obtain the variation of breakup length and penetration height with momentum flux ratio. Using the high speed images, an attempt has been made to understand the physics of the jet breakup process by identification of breakup modes—bag breakup, column breakup, shear breakup, and surface breakup. The results show unique breakup and penetration behavior which departs from the continuous correlations typically used. Furthermore, the images show a substantial spatial fluctuation of the emerging jet resulting in a wavy nature related to effects of instability waves. The results with 15 deg swirl show reduced breakup length and penetration related to the nonuniform distribution of velocity that offers enhanced fuel atomization in swirling fuel nozzles.

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

Volume 1: Compressors, Fans and Pumps; Turbines; Heat Transfer; Combustion, Fuels and Emissions ◽

10.1115/gtindia2017-4655 ◽

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.

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Film Cooling of a Gas Turbine Blade

Journal of Engineering for Power ◽

10.1115/1.3446382 ◽

1978 ◽

Vol 100 (3) ◽

pp. 476-481 ◽

Cited By ~ 78

Author(s):

S. Ito ◽

R. J. Goldstein ◽

E. R. G. Eckert

Keyword(s):

Gas Turbine ◽

Turbine Blade ◽

Film Cooling ◽

Momentum Flux ◽

Flux Ratio ◽

Large Momentum ◽

Gas Turbine Blade ◽

Momentum Flux Ratio ◽

Concave Wall ◽

Convex Wall

The local film-cooling produced by a row of jets on a gas turbine blade is measured by a mass transfer technique. The density of the secondary fluid is from 0.75 to two times that of the mainflow and the range of the mass flux ratio is from 0.2 to three. The effect of blade-wall curvature on the film-cooling effectiveness is very significant. On the convex wall, a near tangential jet is pushed towards the wall by the static pressure force around the jet. For a small momentum flux ratio, this results in a higher effectiveness compared with that on a flat wall. At a large momentum flux ratio, however, the jet tends to move away from the curved wall because of the effect of inertia of the jet resulting in a smaller effectiveness on the convex wall. On the concave wall, the effects of curvature are the reverse of those described for the convex wall.

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