How surfactants influence the drop size in sprays from flat fan and hollow cone nozzles

A pressure-swirl fuel nozzle generating a hollow-cone spray with nominal cone angle of 30 degrees is used in a swirl-stabilized combustor. The combustor is circular in cross section with swirl plate and fuel nozzle axes aligned and coinciding with the axis of the chamber. Kerosene is injected upward inside the chamber from the fuel nozzle. Separate swirl and dilution air flows are uniformly distributed into the chamber that pass through the honey comb flow straighteners and screens. Calculated swirl number of 1.5 is generated with the design swirl plate exit air velocity of 30 degrees with respect to the chamber axis. Effects of swirl and dilution air flow rates on the shape and stability of the flame are investigated. Stable and classical liquid fuel sheet disintegration zone exists close to the nozzle with no visible light followed by a luminous blue region and a mixed blue/yellow region that subsequently turns into yellow for most of the part in the flame. A Phase Doppler Particle Analyzer (PDPA) is used to measure drop size, mean and rms axial velocity for two cases of with and without combustion at six different axial locations from the nozzle. For the no-combustion case all air and fuel flow rates were kept at the same values as the combusting spray condition. Results for mean axial drop velocity profiles indicate widening of the spray due to combustion while the magnitudes of the peak velocities are slightly increased. No measurements inside the hollow-cone spray are possible due to burning of fuel droplets. Drop turbulence decreases due to combination of increase in gas kinematic viscosity and elimination of small drops at high temperatures. Sauter Mean Diameter (SMD) radial profiles at all axial locations increase with combustion due to preferential burning of small drops.

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Measuring Drop Size of Hollow Cone Sprays

Industrial & Engineering Chemistry ◽

10.1021/ie50593a044 ◽

1959 ◽

Vol 51 (5) ◽

pp. 701-702 ◽

Cited By ~ 2

Author(s):

Hikmet Binark ◽

W. E. Ranz

Keyword(s):

Drop Size ◽

Hollow Cone

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EXPERIMENTAL STUDY OF MEAN DROPLET SIZE FROM PRESSURE SWIRL ATOMIZER

International Journal of Engineering Science Technologies ◽

10.29121/ijoest.v4.i6.2020.124 ◽

2020 ◽

Vol 4 (6) ◽

pp. 49-59

Author(s):

Sherry Amedorme

Keyword(s):

Experimental Study ◽

Liquid Film ◽

Drop Size ◽

Injection Pressure ◽

Size Distributions ◽

Sauter Mean Diameter ◽

Hollow Cone ◽

Mean Diameter ◽

Drop Size Distributions ◽

Exit Orifice

This experimental study undertakes the measurements of droplet Sauter Mean Diameter (SMD) at different axial distances for the hollow-cone nozzle and different radial distances from the spray centreline using a laser-diffraction-based drop size analyser in order to validate atomization model. The study also investigates the influence of injection pressure and the evaluation of two exit orifice diameters on the Sauter Mean Diameter (SMD). The drop size distributions along the nozzle centreline as well as the radial drop distributions from spray centreline are also evaluated. To enhance the physics of liquid sheet instability and liquid film breakup mechanisms, visualization of liquid film breakup as a function of injection pressure was carried out. The results show that mean droplet size (SMD) increases in the axial distance on the spray centreline but decreases with an increasing injection pressure on the spray centreline. It was observed that larger sized drops occupy the spray periphery compared to those occupying the spray core. For the nozzle exit orifice diameters of 3.5 mm and 1.5 mm, the results show that the small nozzle exhibits smaller SMDs than the bigger nozzle and the break-up lengths are different for the two nozzles. The drop size distributions at radial positions showed an increase in droplet formation through the spray downstream distances and become more uniform. The visualisation of the spray was carried out using high-speed camera and it was noted that a well-defined hollow-cone spray was captured and that the spray angle increases with the injection pressure but reduces with the liquid film length.

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Modelling Spray Pressure Effects on Droplet Size Distribution from Agricultural Nozzles

Applied Sciences ◽

10.3390/app11199283 ◽

2021 ◽

Vol 11 (19) ◽

pp. 9283

Author(s):

Emanuele Cerruto ◽

Giuseppe Manetto ◽

Rita Papa ◽

Domenico Longo

Keyword(s):

Size Distribution ◽

Drop Size ◽

Droplet Size Distribution ◽

Drop Size Distribution ◽

Pressure Effects ◽

Hollow Cone ◽

Immersion Method ◽

Color Code ◽

Working Pressure ◽

Custom Made

For spray applications, drop size is the most important feature as it affects all aspects of a phytosanitary treatment: biological efficacy, environmental pollution, and operator safety. In turn, drop size distribution depends on nozzle type, liquid properties, and working pressure. In this research, three nozzles were studied under ordinary working conditions and the effect of pressure on drop size distribution was assessed. The nozzles under test, all from Albuz (France), were an orange hollow cone nozzle ATR 80 (European color code), an air induction flat spray nozzle AVI 11003, and an air induction hollow cone nozzle TVI 8002. The ATR 80 and the TVI 8002 nozzles were tested at four pressure values: 0.3, 0.5, 1.0, and 1.5 MPa; the AVI 11003 nozzle was tested at 0.3 and 0.5 MPa. The drop size measurement technique was based on the liquid immersion method by using a custom-made test bench; spray quality parameters were computed by means of suitable functions written in R language. Results showed that an increase in working pressure caused an increase in drop pulverization regardless of the type of nozzle, and drop pulverization was higher for the turbulence nozzle than for the two air induction nozzles. Based on skewness and kurtosis values, the theoretical gamma distribution was the most adapt to fit the experimental data. The scale parameter showed a decreasing trend with the increase in the pressure, a clear index of higher drop pulverization.

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109 Multiple hollow-cone like spray injection from multi-hole nozzle : Photographic spray observation and drop-size measurements by in-flight image analysis

The Proceedings of Conference of Tokai Branch ◽

10.1299/jsmetokai.2005.54.17 ◽

2005 ◽

Vol 2005.54 (0) ◽

pp. 17-18

Author(s):

Takashi SUZUKI ◽

Yasuhide TANI ◽

Yoshiyasu INOUE ◽

Naoki ASANUMA

Keyword(s):

Image Analysis ◽

Drop Size ◽

Hollow Cone

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Electronic Cone Illumination with the Conventional Transmission Electron Microscope

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100077980 ◽

1977 ◽

Vol 35 ◽

pp. 72-73

Author(s):

William Krakow

Keyword(s):

Electronic Device ◽

Chromatic Aberration ◽

Objective Lens ◽

Hollow Cone ◽

Transmission Electron ◽

Lissajous Figures ◽

High Resolution Images ◽

Imaging Mode ◽

Diffraction Patterns ◽

Transmission Microscope

An electronic device has been constructed which manipulates the primary beam in the conventional transmission microscope to illuminate a specimen under a variety of virtual condenser aperture conditions. The device uses the existing tilt coils of the microscope, and modulates the D.C. signals to both x and y tilt directions simultaneously with various waveforms to produce Lissajous figures in the back-focal plane of the objective lens. Electron diffraction patterns can be recorded which reflect the manner in which the direct beam is tilted during exposure of a micrograph. The device has been utilized mainly for the hollow cone imaging mode where the device provides a microscope transfer function without zeros in all spatial directions and has produced high resolution images which are also free from the effect of chromatic aberration. A standard second condenser aperture is employed and the width of the cone annulus is readily controlled by defocusing the second condenser lens.

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Experiments in Bright-Field Imaging with Hollow-Cone Illumination

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100097703 ◽

1981 ◽

Vol 39 ◽

pp. 226-227

Author(s):

W. Kunath ◽

K. Weiss ◽

E. Zeitler

Keyword(s):

Signal To Noise Ratio ◽

Carbon Support ◽

Electronic System ◽

Optic Axis ◽

Hollow Cone ◽

Signal To Noise ◽

Bright Field ◽

Noise Ratio ◽

Single Field ◽

Field Imaging

Bright-field images taken with axial illumination show spurious high contrast patterns which obscure details smaller than 15 ° Hollow-cone illumination (HCI), however, reduces this disturbing granulation by statistical superposition and thus improves the signal-to-noise ratio. In this presentation we report on experiments aimed at selecting the proper amount of tilt and defocus for improvement of the signal-to-noise ratio by means of direct observation of the electron images on a TV monitor.Hollow-cone illumination is implemented in our microscope (single field condenser objective, Cs = .5 mm) by an electronic system which rotates the tilted beam about the optic axis. At low rates of revolution (one turn per second or so) a circular motion of the usual granulation in the image of a carbon support film can be observed on the TV monitor. The size of the granular structures and the radius of their orbits depend on both the conical tilt and defocus.

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Three-fold astigmatism: An important TEM aberration

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100150691 ◽

1993 ◽

Vol 51 ◽

pp. 972-973 ◽

Cited By ~ 1

Author(s):

O.L. Krivanek ◽

M.L. Leber

Keyword(s):

High Resolution ◽

Spatial Frequency ◽

Field Emission ◽

Azimuthal Angle ◽

Hollow Cone ◽

Small Probe ◽

Wide Range ◽

High Resolution Images ◽

Image Position

Three-fold astigmatism resembles regular astigmatism, but it has 3-fold rather than 2-fold symmetry. Its contribution to the aberration function χ(q) can be written as:where A3 is the coefficient of 3-fold astigmatism, λ is the electron wavelength, q is the spatial frequency, ϕ the azimuthal angle (ϕ = tan-1 (qy/qx)), and ϕ3 the direction of the astigmatism.Three-fold astigmatism is responsible for the “star of Mercedes” aberration figure that one obtains from intermediate lenses once their two-fold astigmatism has been corrected. Its effects have been observed when the beam is tilted in a hollow cone over a wide range of angles, and there is evidence for it in high resolution images of a small probe obtained in a field emission gun TEM/STEM instrument. It was also expected to be a major aberration in sextupole-based Cs correctors, and ways were being developed for dealing with it on Cs-corrected STEMs.

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