scholarly journals Interpreting Liquid Atomization Efficiency

2021 ◽  
Vol 2 (5) ◽  
Keyword(s):  
Drop Size ◽  
General Definition ◽  
Design Tools ◽  
Sauter Mean Diameter ◽  
Future Directions ◽  
Mean Diameter ◽  
Liquid Atomization ◽  
Atomization Efficiency ◽  
Injector Design

Liquid atomization involves several mechanisms transforming a bulk of liquid into small droplets. The atomization efficiency usefulness is questionable considering its low values (0.01-1%). This work presents a general definition for atomization efficiency and explains why the Sauter mean diameter is the appropriate characteristic drop size (and no other mean diameter value). Finally, future directions are suggested for developing injector design tools from atomization efficiency.

Drop Size Measurements in Evaporating Realistic Sprays of Emulsified and Neat Fuels

1983 ◽  
Author(s):  
Lee G. Dodge ◽  
Clifford A. Moses
Keyword(s):  
Drop Size ◽  
Elevated Temperatures ◽  
Jet Fuel ◽  
Sauter Mean Diameter ◽  
Emulsified Fuel ◽  
Fuel Jet ◽  
Mean Diameter ◽  
Detailed Computer ◽  
Particle Sizer ◽  
Additional Point

A comparative study has been performed of the drop-size distribution of sprays of emulsified and neat distillate-type aviation fuels at elevated temperatures (308K to 700K) and pressures (101 kPa to 586 kPa). All drop-size data were obtained with a Malvern Model 2200 Particle Sizer based on the forward angle diffraction pattern produced by the drops when illuminated by a collimated HeNe laser beam. Fuels included a standard multicomponent jet fuel, Jet-A, and a single component fuel, hexadecane, in both neat form and emulsified with 20 percent (by vol.) water and 2 percent (by vol.) surfactant. The initial breakup and atomization of a neat and emulsified fuel were quite similar at all conditions, and the evaporation rates appeared similar at various temperatures for pressures at or below about 300 kPa. At higher pressures with elevated temperatures the emulsified fuels of both types produce drops of significantly smaller Sauter mean diameter than the neat fuels as distance from the nozzle increases. These results are consistent with the microexplosion hypothesis, but there could also be alternative explanations. A detailed computer model which predicts heat up rates, steady state drop temperatures, evaporation rates, and drop trajectories has been used to help interpret the results. An additional point which has been observed is that the initial Sauter mean diameter produced with constant differential nozzle pressure is dependent on the air pressure with an exponent of about −0.4, i.e., SMD ∼ Pair−0.4. Some recent correlations often quoted omit the pressure (density) of air term.

scholarly journals Experimental Study of the Effect of Dense Spray on Drop Size Measurement by Light Scattering Technology

1990 ◽  
Author(s):  
Ju Shan Chin ◽  
Wei Ming Li ◽  
Yan Zhang
Keyword(s):  
Experimental Data ◽  
Light Scattering ◽  
Correction Factor ◽  
Drop Size ◽  
Empirical Equation ◽  
Size Measurement ◽  
Sauter Mean Diameter ◽  
Internal Mixing ◽  
Mean Diameter ◽  
Factor Data

The effect of dense spray on drop size measurement by light scattering technology was studied by using Malvern instrument with five duplicated internal mixing airblast atomizers aligned in line with laser beam. The correction factor data for multiple scattering were obtained. By regression analysis, an empirical equation was obtained which correlated the correction factor as a function of obscuration (OBS), Sauter mean diameter under dilute spray condition SMD0. and drop size distribution parameter for Rosin–Rammler distribution under dilute spray conditions N0. The experimental data showed definitely that the correction factor is not only a function of OBS, SMD0, as proposed by Dodge, but also is a function of N0. The correlation fits the experimental data very well, and can be used for practical purposes to correct the data from Malvern drop sizer at high obscuration conditions.

scholarly journals EXPERIMENTAL STUDY OF MEAN DROPLET SIZE FROM PRESSURE SWIRL ATOMIZER

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.

Effect of Dispersed Phase Viscosity on Emulsification in Turbulence Flow

2013 ◽  
Vol 446-447 ◽  
pp. 571-575 ◽  
Author(s):  
Chen Wei Liu ◽  
Ming Zhong Li
Keyword(s):  
Experimental Study ◽  
Drop Size ◽  
Dispersed Phase ◽  
Drop Diameter ◽  
Volume Distribution ◽  
Size Distributions ◽  
Sauter Mean Diameter ◽  
Turbulence Flow ◽  
Mean Diameter ◽  
Drop Size Distributions

Systematic experimental study has been performed to examine the effects of dispersed phase viscosity on emulsification in turbulence flow. It is found that the volume drop size distributions widen as dispersed phase viscosity increased; at lower dispersed phase viscosity, both Sauter mean diameter and the maximum stable diameter increase with the viscosity, while at higher dispersed phase viscosity, Sauter mean diameter and the maximum stable diameter decreasing and increasing, respectively. It has also been found that linear relation between the Sauter mean diameter and the maximum stable drop diameter is still valid for the emulsions which show a bimodal volume distribution, and the proportional constant decreases as dispersed phase viscosity increases.

Effect of Geometric Parameters on Mean Drop Sizes From Dual-Orifice Pressure Nozzles

2018 ◽  
Vol 141 (2) ◽  
Author(s):  
Xiao Wei ◽  
Guo Zhengyan ◽  
Chen Pimin
Keyword(s):  
Satisfactory Agreement ◽  
Drop Size ◽  
Discharge Coefficient ◽  
Experimental Studies ◽  
Sauter Mean Diameter ◽  
Atomization Process ◽  
Outer Flow ◽  
Mean Diameter ◽  
Nozzle Geometries ◽  
Semi Empirical

Experimental studies have been conducted to investigate the effect of nozzle geometries on the atomization. Extensive measurements of mean drop size are conducted on the 15 dual-orifice pressure nozzles. These nozzles provide a range of discharge coefficient from 0.06 to 0.13. These experimental results are used to substantiate a semi-empirical correlation derived for determining the Sauter mean diameter (SMD) of sprays generated by dual-orifice pressure nozzles. The correlation is obtained by modeling the liquid internal and outer flow that govern the atomization process in dual-orifice pressure nozzles. A very satisfactory agreement is demonstrated between the predictions based on the correlations and the actual measured values of the SMD.

Analysis of Sauter Mean Diameter (SMD) for Fuel Sprays

2007 ◽  
Author(s):  
Badih A. Jawad ◽  
Chris H. Riedel
Keyword(s):  
Drop Size ◽  
Time Pressure ◽  
Injection Pressure ◽  
Temporal Variations ◽  
Chamber Pressure ◽  
Sauter Mean Diameter ◽  
Fuel Sprays ◽  
Fuel Density ◽  
Mean Diameter ◽  
Ambient Gas

The spray-tip penetrations and the drop sizes of intermittent fuel sprays were measured by using a modified pulsed optical spray sizer. The average spray tip speeds were determined from simultaneously recorded needle lift signals and obscuration traces. The speeds of a sequence of fuel pulses injected at ∼103 Hz were analyzed to elucidate penetration mechanisms. A correlation that relates penetration distance to time, pressure drop across the nozzle, fuel density, and ambient gas density was obtained. The temporal variations of drop size in penetrating pulses of sprays were measured. The concentration of drops were calculated by combining drop size and obscuration data. The Sauter mean diameter of penetrating fuel drops increased with an increase of the chamber pressure and decreased with an increase of the injection pressure.

Experimental Study of the Effect of Dense Spray on Drop Size Measurement by Light Scattering Technology

1992 ◽  
Vol 114 (1) ◽  
pp. 82-88 ◽  
Author(s):  
Ju Shan Chin ◽  
Wei Ming Li ◽  
Yan Zhang
Keyword(s):  
Experimental Data ◽  
Light Scattering ◽  
Correction Factor ◽  
Drop Size ◽  
Empirical Equation ◽  
Size Measurement ◽  
Sauter Mean Diameter ◽  
Internal Mixing ◽  
Mean Diameter ◽  
Factor Data

The effect of dense spray on drop size measurement by light scattering technology was studied using a Malvern instrument with five duplicated internal mixing airblast atomizers aligned with a laser beam. The correction factor data for multiple scattering were obtained. By regression analysis, an empirical equation was obtained that correlated the correction factor as a function of obscuration (OBS), Sauter mean diameter under dilute spray condition (SMD0), and drop size distribution parameter for Rosin-Rammler distribution under dilute spray conditions (N0). The experimental data showed definitely that the correction factor is not only a function of OBS and SMD0, as proposed by Dodge, but also is a function of N0. The correlation fits the experimental data very well, and can be used for practical purposes to correct the data from the Malvern drop sizer at high obscuration conditions.

Fuel Leaking Analysis of Fuel Tank by Projectiles Impact with Mechanical Properties of Projectiles

2013 ◽  
Vol 644 ◽  
pp. 203-206
Author(s):  
Hai Liang Cai ◽  
Bi Feng Song ◽  
Yang Pei ◽  
Shuai Shi
Keyword(s):  
High Speed ◽  
Drop Size ◽  
Fuel Tank ◽  
Size Distributions ◽  
Sauter Mean Diameter ◽  
Fuel Droplets ◽  
High Speed Impact ◽  
Fuel Tanks ◽  
Rigid Projectile ◽  
Drop Size Distributions

For making sure the dry bay ignition and fire, it’s necessary to calculate the number and the sizes of the droplets and determine the mass flow rate of the fuel induced by high-speed impact and penetration of a rigid projectile into fuel tank. An analytical model is founded and the method for calculating the initial leaking velocity of the fuel is determined. It gives the equation for calculating the drop size distributions of fuel and the Sauter mean diameter (SMD) of droplets, through the Maximum Entropy Theory and the conservation for mass. Using the Harmon’s equation for SMD,the fuel droplets SMD can be calculated. Results shows that the initial leaking velocity of the fuel is about linearly increasing with the velocity of the projectile, the SMD of fuel droplets increases with the hole size of the fuel tank which induced by the penetration of the projectile and linearly decreases with the velocity of the projectile. The results can be used for the ignition and fire analysis of the dry bay adjacent to fuel tanks.

Mean Diameters in Parallel-Flow and Counter-Flow Aerosol Systems

1976 ◽  
Vol 98 (2) ◽  
pp. 297-302 ◽  
Author(s):  
K. G. T. Hollands ◽  
K. C. Goel
Keyword(s):  
Mass Transfer ◽  
Continuous Phase ◽  
General Concept ◽  
Parallel Flow ◽  
General Definition ◽  
Single Pair ◽  
Counter Flow ◽  
Mean Diameter ◽  
The Mean ◽  
Definition Of

The general concept of the mean diameter of the disperse phase of an aerosol system, first introduced by Mugele and Evans in 1951, has proven to be a very useful one. In this concept, the proper mean diameter, xp,q, is characterized by a single pair of indices, p and q, which are dependent on the actual type of aerosol system under consideration. This paper re-examines the validity of this concept of mean diameter in heat and mass transfer aerosol systems. The concept is found to be applicable only under a very narrow range of conditions. Attention is then given to a more general definition of a mean diameter, applicable to aerosol heat or mass exchangers. Analyses of these devices shows that the more general mean diameter is a function of the capacity rate ratio, R, and effectiveness of the heat exchanger, ε. Solutions to the governing equations have permitted the mean diameter to be presented graphically as a function of these variables. These solutions are given for two types of particle size distributions, the Rosin-Rammler and the log-probability, and for both parallel-flow and counter-flow heat exchangers. The solutions are, however, restricted to cases where the resistance to heat or mass transfer lies exclusively in the continuous phase.

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