The Influence of Liquid Film Thickness on Airblast Atomization

1980 ◽  
Vol 102 (3) ◽  
pp. 706-710 ◽  
Author(s):  
N. K. Rizk ◽  
A. H. Lefebvre
Keyword(s):  
Film Thickness ◽  
Liquid Film ◽  
Drop Size ◽  
Porous Plate ◽  
Liquid Films ◽  
Liquid Sheet ◽  
Liquid Film Thickness ◽  
Air Stream ◽  
And Control ◽  
The Relationship

The influence of initial liquid film thickness on mean drop size and drop-size distribution was examined using two specially designed airblast atomizers. Both were constructed to produce a flat liquid sheet across the centerline of a two-dimensional air duct with the liquid sheet exposed on both sides to high velocity air. In one case a thin film of uniform thickness was produced by injecting the liquid through a porous plate located just upstream of the atomizing edge. The film thickness, t, was then measured by a needle contact device. In the second design the fuel entered the air stream through a thin slot whose height could be adjusted accurately to vary and control the initial film thickness. Drop sizes were measured by the well-established light-scattering technique. From analysis of the processes involved, and from correlation of the experimental data, it was found that high values of liquid viscosity and liquid flow rate result in thicker films. It was also observed that thinner liquid films produce better atomization, according to the relationship, SMD ∝ t0.38.

Theoretical Model of Electric Field Effects on the Enhancement of Critical Heat Flux

2004 ◽  
Author(s):  
Takeshi Yajima ◽  
Akira Yabe ◽  
Hiroshi Maki
Keyword(s):  
Surface Tension ◽  
Heat Flux ◽  
Film Thickness ◽  
Liquid Film ◽  
Critical Heat Flux ◽  
Applied Voltage ◽  
Liquid Film Thickness ◽  
Flux Enhancement ◽  
The Relationship ◽  
Lines Of Force

Critical heat flux enhancement by the electrohydrodynamic (EHD) effect has been analyzed quantitatively based on the increased frequency of liquid-vapor interface oscillations around the edge of the bubble. The majority of heat transfer occurs when the liquid film thickness becomes less than 50 μ m, which only occurs once per period. The main mechanism of heat flux enhancement induced by the EHD effect would be a result of an increase in surface tension due to the effect of electric lines of force. By representing the terms of the forces for a change in curvature and the surface tension resulting from the electric lines of force, the equation of the liquid-vapor instability was obtained and analyzed. Experimentally it has been shown that as the applied voltage increased, the periodic time interval of the thickness change was shortened. This effect reduces the potential for dryout of the liquid film by making the minimum thickness time period shorter. By measuring the pressure oscillation on the boiling surface, the change of the thin liquid film thickness and the dynamic shape of bubbles, the relationship among the pressure, the liquid film thickness and the bubble shape was clarified. Consequently, this model successfully explains the relationship between the applied voltage and the enhancement of the critical heat flux.

Fluorescence and Fiber-Optics Based Real-Time Thickness Sensor for Dynamic Liquid Films

2009 ◽  
Vol 132 (3) ◽  
Author(s):  
T. W. Ng ◽  
A. Narain ◽  
M. T. Kivisalu
Keyword(s):  
Film Thickness ◽  
Liquid Film ◽  
Fiber Optics ◽  
Calibration Procedure ◽  
Liquid Films ◽  
Flow Dynamics ◽  
Liquid Film Thickness ◽  
Fiber Optic Technology ◽  
Thickness Measurements ◽  
Film Flows

To overcome the limitations/disadvantages of many known liquid film thickness sensing devices (viz. conductivity probes, reflectance based fiber-optics probes, capacitance probes, etc.), a new liquid film thickness sensor that utilizes fluorescence phenomena and fiber-optic technology has been developed and reported here. Measurements from this sensor are expected to facilitate better understanding of liquid film dynamics in various adiabatic, evaporating, and condensing film flows. The sensor accurately measures the instantaneous thickness of a dynamically changing liquid film in such a way that the probe does not perturb the flow dynamics in the proximity of the probe’s tip. This is achieved by having the probe’s exposed surface embedded flush with the surface over which the liquid film flows, and by making arrangements for processing the signals associated with the emission and collection of light (in distinctly different wavelength windows) at the probe’s flush surface. Instantaneous film thickness in the range of 0.5–3.0 mm can accurately (with a resolution that is within ±0.09 mm over 0.5–1.5 mm range and within ±0.18 mm over 1.5–3.0 mm range) be measured by the sensor described in this paper. Although this paper only demonstrates the sensor’s ability for dynamic film thickness measurements carried out for a doped liquid called FC-72 (perfluorohexane or C6F14 from 3M Corporation, Minneapolis, MN), the approach and development/calibration procedure described here can be extended, under similar circumstances, to some other liquid films and other thickness ranges as well.

Liquid Film Features Analysis on Mechanical Seals with Micro-Pore Face by CFD

2011 ◽  
Vol 354-355 ◽  
pp. 575-578
Author(s):  
Wei Zheng Zhang ◽  
Shu Rong Yu ◽  
Yan Wang ◽  
Xue Xing Ding
Keyword(s):  
Film Thickness ◽  
Liquid Film ◽  
Optimization Design ◽  
Theoretical Data ◽  
Least Square ◽  
Liquid Film Thickness ◽  
Stable Operation ◽  
Mechanical Seals ◽  
Film Stiffness ◽  
The Relationship

The six kinds of different models were simulated by FLUENT software under certain circumstances. As a result, their pressure distributions and liquid film opening force with different thickness were obtained. The relationship between liquid film thickness and opening force was obtained by least square fitting. And then the relationship between stiffness and liquid film thickness was calculated and analyzed. The result shows that: seal opening force and liquid film stiffness decrease as the liquid film thickness increase, this simulation results is identical with the theoretical data. In larger film thickness range, the opening force is larger, and so was the liquid film stiffness, which provide the basis for seal optimization design and the stable operation.

Fluorescence and Fiber-Optics Based Real-Time Thickness Sensor for Dynamic Liquid Films

2007 ◽  
Author(s):  
T. W. Ng ◽  
A. Narain
Keyword(s):  
Film Thickness ◽  
Liquid Film ◽  
Fiber Optics ◽  
Calibration Procedure ◽  
Liquid Films ◽  
Flow Dynamics ◽  
Liquid Film Thickness ◽  
Fiber Optic Technology ◽  
Thickness Measurements ◽  
Film Flows

To overcome the limitations/disadvantages of many known liquid film thickness sensing devices (viz. conductivity probes, reflectance based fiber-optics probes, capacitance probes, etc.), a new liquid film thickness sensor that utilizes fluorescence phenomena and fiber-optic technology has been developed and reported here. Measurements from this sensor are expected to facilitate better understanding of liquid film dynamics in various adiabatic, evaporating, and condensing film flows. The sensor accurately measures the instantaneous thickness of a dynamically changing liquid film in such a way that the probe does not perturb the flow dynamics in the proximity of the probe’s tip. This is achieved by having the probe’s exposed surface embedded flush with the surface over which the liquid film flows, and by making arrangements for processing the signals associated with the emission and collection of light (in distinctly different wavelength windows) at the probe’s flush surface. Instantaneous film thickness in the range of 0.5 to 3.0 mm can accurately (with a resolution that is within +/− 0.09 mm over 0.5 to 1.5 mm range and within +/− 0.18 mm over 1.5 to 3.0 mm range) be measured by the sensor described in this paper. Although this paper only demonstrates the sensor’s ability for dynamic film thickness measurements carried out for a doped liquid called FC-72 (perfluorohexane or C6F14 from 3M Corporation), the approach and development/calibration procedure described here can be extended, under similar circumstances, to some other liquid films as well.

Study on Liquid Film Thickness of Accelerated Slug Flow in Micro Tubes

2014 ◽  
Author(s):  
Kenshiro Muramatsu ◽  
Youngjik Youn ◽  
Youngbae Han ◽  
Keishi Yokoyama ◽  
Yosuke Hasegawa ◽  
...  
Keyword(s):  
Film Thickness ◽  
Liquid Film ◽  
Slug Flow ◽  
Liquid Film Thickness

Experimental comparison of the spray atomization of heavy and light fuel oil at different temperatures and pressures for pressure-swirl injector

2021 ◽  
pp. 095765092199437
Author(s):  
Elyas Rostami ◽  
Hossein Mahdavy Moghaddam
Keyword(s):  
Film Thickness ◽  
Liquid Film ◽  
Diesel Fuel ◽  
Temperature Increase ◽  
Liquid Film Thickness ◽  
Fuel Oil ◽  
Spray Angle ◽  
Breakup Length ◽  
Fuel Atomization ◽  
Mean Diameter

In this study, the atomization of heavy fuel oil (Mazut) and diesel fuel at different pressures is compared experimentally. Also, the effects of temperature on the Mazut fuel atomization are investigated experimentally. Mass flow rate, discharge coefficient, wavelength, liquid film thickness, ligament diameter, spray angle, breakup length, and sature mean diameter are obtained for the Mazut and diesel fuel. Fuels spray images at different pressures and temperatures are recorded using the shadowgraphy method and analyzed by the image processing technique. Error analysis is performed for the experiments, and the percentage of uncertainty for each parameter is reported. The experimental results are compared with the theoretical results. Also, Curves are proposed and plotted to predict changes in the behavior of atomization parameters. Diesel fuel has less viscosity than Mazut fuel. Diesel fuel has shorter breakup length, wavelength, liquid film thickness, and sature mean diameter than Mazut fuel at the same pressure. Diesel fuel has a larger spray angle and a larger discharge coefficient than Mazut fuel at the same pressure. As the pressure and temperature increase, fuel atomization improves. The viscosity of Mazut fuel is decreased by temperature increase. As the fuel injection pressure and temperature increase, breakup length, wavelength, liquid film thickness, and sature mean diameter decrease; also, spray angle increases.

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