High Weber Number SMD Correlations for Pressure Atomizers

1986 ◽  
Vol 108 (1) ◽  
pp. 191-195 ◽  
Author(s):  
J. B. Kennedy
Keyword(s):  
Pressure Drop ◽  
Weber Number ◽  
Fuel Temperature ◽  
Sauter Mean Diameter ◽  
Atomization Process ◽  
Fuel Density ◽  
System Of Units ◽  
Nozzle Size ◽  
Mean Diameter ◽  
Shear Type

Published correlations for the Sauter Mean Diameter (SMD) of sprays produced by pressure atomizing injectors have generally taken the form, SMD = Aω˙B ΔPC. The system of units and the fuel properties are reflected by the coefficient A. The exponent of the flow rate term (B) has been found to be approximately 0.20. There has been less agreement relative to the appropriate value of the pressure drop exponent (C). Simmons [1] reported the value of the pressure drop exponent to be 0.354, and this value has been widely used. This paper presents recently acquired experimental data that reveal that for We greater than 10.0 a different atomization process occurs, i.e., “shear-type” breakup, which results in much finer atomization than predicted by previously reported correlations. To accurately represent the high We data, a significantly different SMD correlation form is required and is reported in this paper. The effects of large variations in the nozzle size, fuel density, viscosity, surface tension, and fuel temperature have been included in the derivation of the correlations.

Variation of Sauter Mean Diameter of Droplets of Gasoline Engine Intake Port during Cold Start

2012 ◽  
Vol 433-440 ◽  
pp. 6390-6396
Author(s):  
Pei Yong Ni ◽  
Xiang Li Wang
Keyword(s):  
Engine Speed ◽  
Gasoline Engine ◽  
Cold Start ◽  
Droplet Velocity ◽  
Injection Timing ◽  
Fuel Temperature ◽  
Sauter Mean Diameter ◽  
Initial Droplet ◽  
Mean Diameter ◽  
Fuel Evaporation

The reduction of sauter mean diameter (SMD) of droplets means the percent of the evaporated fuel, which is important to the formation of the combustible mixture in a port-injection gasoline engine during cold-start. Three-dimensional numerical simulation of SMD of the droplets in the inlet port of a gasoline engine was employed using the CFD software. This paper presented the effect of multi-parameters on SMD of the droplets including initial droplet velocity, intake temperature, fuel temperature, injection timing and engine speed. The simulation results show that the most influential parameters on SMD of the droplets are intake temperature and fuel temperature. The fuel evaporation rates increase approximately linearly with the intake air temperature and fuel temperature increasing. The initial droplet velocity and injection timing have a little effect on the fuel evaporation. As engine speed increases, SMD of the droplets firstly decreases and then increases. After intake-valve-open (IVO), back flow of gas in cylinders results in steep reduction of droplet diameter.

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.

scholarly journals Study on Interfacial Surface in Modified Spray Tower

Processes ◽  
2019 ◽  
Vol 7 (8) ◽  
pp. 532 ◽  
Author(s):  
Marek Ochowiak ◽  
Sylwia Włodarczak ◽  
Ivan Pavlenko ◽  
Daniel Janecki ◽  
Andżelika Krupińska ◽  
...  
Keyword(s):  
Reynolds Number ◽  
Pressure Drop ◽  
Power Law ◽  
Inside Surface ◽  
Process Efficiency ◽  
Sauter Mean Diameter ◽  
Spray Tower ◽  
Interfacial Surface ◽  
Mean Diameter ◽  
Droplet Sizes

This paper presents an analysis of the changes in interfacial surface and the size of droplets formed in a spray tower. The interfacial surface and the size of droplets formed are of fundamental importance to the performance of the equipment, both in terms of pressure drop and process efficiency. Liquid film and droplet sizes were measured using a microphotography technique. The confusors studied were classical, with profiled inside surface, and with double profiled inside surface. The liquids studied were water and aqueous solutions of high-molecular polyacrylamide (PAA) of power-law characteristics. The ranges of process Reynolds number studied were as follows: ReG ∈ (42,700; 113,000), ReL ∈ (170; 15,200). A dimensionless correlation for reduced Sauter mean diameter is proposed.

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.

Some Effects of Using Water as a Test Fluid in Fuel Nozzle Spray Analysis

1981 ◽  
Vol 103 (1) ◽  
pp. 118-123 ◽  
Author(s):  
H. C. Simmons ◽  
C. F. Harding
Keyword(s):  
Weber Number ◽  
Systematic Investigation ◽  
Test Fluid ◽  
Sauter Mean Diameter ◽  
Liquid Pressure ◽  
Flow Capacity ◽  
Mean Diameter ◽  
Small Flow ◽  
Fuel Nozzle ◽  
Discharge Orifice

A systematic investigation was made of the differences in atomizing performance between water and kerosene fuel for six simplex fuel nozzles of small flow capacity. A large number of tests was run using two methods of spray analysis, to determine the effect of nozzle liquid pressure drop (ΔPF) on Sauter Mean Diameter (SMD). It was found that there is a clearly-defined relationship dependent on both the relative values of surface tension and also on a Weber Number calculated for conditions in the liquid film at the nozzle discharge orifice. It is concluded that large errors in estimating SMD for modeling programs are possible if results observed with water are assumed to be representative of behavior with kerosene fuel.

scholarly journals Atomization Quality of Twin Fluid Atomizers for Gas Turbines

1982 ◽  
Author(s):  
M. M. Elkotb ◽  
M. A. Elsayed Mahdy ◽  
M. E. Montaser
Keyword(s):  
Size Distribution ◽  
Droplet Size ◽  
Gas Turbines ◽  
Cone Angle ◽  
Droplet Size Distribution ◽  
Diameter Ratio ◽  
Air Pressure ◽  
Sauter Mean Diameter ◽  
Flow Number ◽  
Mean Diameter

A detailed investigation of the effect of nozzle/needle diameter ratio, normal fuel area, swirler degree, air pressure, fuel pressure on flow number, cone angle and droplet size distribution of external mixing twin fluid atomizers is given in this paper. Forty atomizers have been constructed to prevent mutual effect of various parameters. Flow number and cone angle are found to increase with nozzle/diameter ratio, and to decrease with the increase of air pressure. Optimum fuel flow is obtained at swirler angle 30-deg, while cone angle increases with increase of swirler angle. Sauter mean diameter decreases with the increase of air pressure and decrease of fuel pressure. Suitable functions are derived for droplet size distribution, Sauter mean diameter, and flow number. They are suitable to predict the geometry of the atomizer and to be used also in a prediction model for the calculation of fuel concentration and heat release.

Bubble Entrapment in Sprayed Films

2014 ◽  
Author(s):  
A. Dalili ◽  
S. Chandra ◽  
J. Mostaghimi ◽  
H. T. Charles Fan ◽  
J. C. Simmer
Keyword(s):  
Surface Tension ◽  
Film Thickness ◽  
The Other ◽  
Bubble Motion ◽  
Sauter Mean Diameter ◽  
Glass Substrates ◽  
Buoyancy Forces ◽  
Mean Diameter ◽  
Imagej Software ◽  
Bubble Movement

A compressed air sprayer was used to spray model paint onto two glass substrates at the same time. Afterwards, one glass substrate was placed on a LED light source and still photographs were taken from the top using a DSLR camera with a timer system. The other substrate was put on a balance to record weight. Pictures and weight measurements were taken at 5 second intervals for 15 minutes. The sprayed film thickness was varied. The pictures were analyzed using ImageJ software. Bubble Count vs. Time, Sauter Mean Diameter (SMD) of Bubbles vs. Time as well as Weight vs. Time was plotted. It was seen that the pace of weight loss was faster for thinner films. The rate of bubble escape also depended on film thickness. It took a longer time for thicker films to lose the bubbles entrapped in them. In the first 30 seconds, large bubbles escaped due to buoyancy forces and afterwards surface-tension driven flows became dominant. There was also a lot of bubble movement in thicker films. The effect of gravity was studied as well. Gravity did not affect the bubble escape rate since a downward facing film had the same bubble count as an upward facing film confirming that bubble motion was not due to buoyancy forces alone. However, the SMD of bubbles in a downward facing film was larger than an upward facing film. Buoyancy is not a factor in bubble escape from the downward facing film and only surface-tension driven flows play a role.

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.

An Experimental and Computational Investigation on the Pre-Heating of Fuel to Improve Cold Starting of Diesel Engines

2003 ◽  
Author(s):  
Gurpreet S. Gambhir ◽  
Duane L. Abata ◽  
Donna J. Michalek
Keyword(s):  
Ambient Air ◽  
Computational Investigation ◽  
Fuel Temperature ◽  
Sauter Mean Diameter ◽  
Ambient Temperatures ◽  
Cold Starting ◽  
Compression Ignition Engines ◽  
Cold Room ◽  
Physical Phenomena ◽  
Efflux Velocity

This paper describes the effect of elevated fuel temperature on cold starting operability in compression ignition engines. This study was based on the hypothesis that in a cold start condition, fuel heated to a temperature higher than the surrounding ambient air before it enters the combustion chamber would improve cold starting. Experiments on heating the injector and the fuel before the injection event were performed in a cold room facility with ambient temperatures varying from −20 degrees to 20 degrees Celsius. A computational analysis of the injector was conducted using Star-CD to more fully understand the physical phenomena involved and help explain results obtained from the experiment. Results indicated that fuel heating does affect the efflux velocity, Sauter mean diameter and the lifetime of a fuel droplet. Droplet break-up time and spray penetration are not much affected. Computational and experimental results were within 30% of each other. Results of this work should be useful in the design of improved cold starting methods of diesel fueled engines.

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