Factors Influencing the Circumferential Liquid Distribution From Pressure-Swirl Atomizers

1993 ◽  
Vol 115 (3) ◽  
pp. 447-452 ◽  
Author(s):  
S. K. Chen ◽  
A. H. Lefebvre ◽  
J. Rollbuhler
Keyword(s):  
Beneficial Effect ◽  
Injection Pressure ◽  
Diameter Ratio ◽  
Liquid Viscosity ◽  
Flow Number ◽  
Liquid Distribution ◽  
Swirl Chamber ◽  
Factors Influencing ◽  
Pressure Swirl ◽  
Discharge Orifice

Measurements of circumferential liquid distribution are carried out over ranges of injection pressure from 0.34 to 1.72 MPa (50 to 250 psi) using five different simplex nozzles to achieve variations in the discharge orifice length/diameter ratio from 0.5 to 4.0. Two additional simplex nozzles of the same flow number are also examined in order to ascertain the effect of variations in the number of swirl chamber feed slots on circumferential liquid distribution. Mixtures of water and glycerine are used to provide a twelve to one variation in liquid viscosity. The results obtained show that spray uniformity improves markedly at higher injection pressures. Increase in liquid viscosity also has a beneficial effect on spray uniformity. The most uniform circumferential liquid distributions are obtained with nozzles having a discharge orifice length/diameter ratio of between 1 1/2 and 2.

Factors Influencing the Effective Spray Cone Angle of Pressure-Swirl Atomizers

1992 ◽  
Vol 114 (1) ◽  
pp. 97-103 ◽  
Author(s):  
S. K. Chen ◽  
A. H. Lefebvre ◽  
J. Rollbuhler
Keyword(s):  
Cone Angle ◽  
Injection Pressure ◽  
Diameter Ratio ◽  
Liquid Viscosity ◽  
Spray Cone Angle ◽  
Spray Cone ◽  
Swirl Chamber ◽  
Factors Influencing ◽  
Pressure Swirl ◽  
Discharge Orifice

The spray cone angles produced by several simplex pressure-swirl nozzles are examined using three liquids whose viscosities range from 0.001 to 0.012 kg/ms (1 to 12 cp). Measurements of both the visible spray cone angle and the effective spray cone angle are carried out over wide ranges of injection pressure and for five different values of the discharge orifice length/diameter ratio. The influence of the number of swirl chamber feed slots on spray cone angle is also examined. The results show that the spray cone angle widens with increase in injection pressure but is reduced by increases in liquid viscosity and/or discharge orifice length/diameter ratio. Variation in the number of swirl chamber feed slots between one and three has little effect on the effective spray cone angle.

Influence of Geometric Features on the Performance of Pressure-Swirl Atomizers

1990 ◽  
Vol 112 (4) ◽  
pp. 579-584 ◽  
Author(s):  
S. K. Chen ◽  
A. H. Lefebvre ◽  
J. Rollbuhler
Keyword(s):  
Drop Size ◽  
Cone Angle ◽  
Diameter Ratio ◽  
Working Fluid ◽  
Spray Characteristics ◽  
Spray Cone Angle ◽  
Liquid Distribution ◽  
Spray Cone ◽  
Pressure Swirl ◽  
Discharge Orifice

The spray characteristics of several different simplex pressure-swirl nozzles are examined using water as the working fluid. Measurements of mean drop size, dropsize distribution, effective spray cone angle, and circumferential liquid distribution are carried out over wide ranges of injection pressure. Eight different nozzles are employed in order to achieve a wide variation in the length/diameter ratio of the final discharge orifice. Generally, it is found that an increase in discharge orifice length/diameter ratio (lo/do) increases the mean drop size in the spray and reduces the spray cone angle. The circumferential liquid distribution is most uniform when lo/do=2. If lo/do is raised above or lowered below this optimum value, the circumferential uniformity of the liquid distribution is impaired. The observed effects of lo/do on spray characteristics are generally the same regardless of whether the change in lo/do is accomplished by varying lo or do.

Film Thickness, Droplet Size Measurements and Correlations for Large Pressure-Swirl Atomizers

1998 ◽  
Author(s):  
M. A. Benjamin ◽  
A. Mansour ◽  
U. G. Samant ◽  
S. Jha ◽  
Y. Liao ◽  
...  
Keyword(s):  
Film Thickness ◽  
Droplet Size ◽  
Large Scale ◽  
Spray Angle ◽  
Orifice Diameter ◽  
Flow Number ◽  
Swirl Chamber ◽  
Large Pressure ◽  
Nozzle Geometries ◽  
Pressure Swirl

A parametric experimental study has been conducted to measure the discharge coefficient, the flow number, the film thickness, the spray angle, the velocity coefficient and droplet size of a large-scale simplex nozzle using ultrasonic and optical techniques. Seventeen nozzle geometries have been studied for three mass flow rates. The large-scale nozzle provides adequate resolution for measurements of film thickness, spray angle, and droplet size. The experimental data collected have been used to derive new and improved correlations for nozzle flow and breakup parameters. It is found that the atomizer constant (ratio of total inlet area to product of the swirl chamber and orifice diameter) is the primary parameter affecting the atomizer performance. As the atomizer constant increases, the discharge and velocity coefficients increase and the spray angle decreases.

Microfabrication and Laser Diagnosis of Pressure-Swirl Atomizers

2003 ◽  
Author(s):  
Ker-Jer Huang ◽  
Alex C. Chen ◽  
Jing-Tang Yang
Keyword(s):  
Injection Molding ◽  
Plasma Etching ◽  
Design Parameters ◽  
Channel Diameter ◽  
X Ray ◽  
Swirl Chamber ◽  
Phase Doppler Particle Analyzer ◽  
Pressure Swirl ◽  
Discharge Orifice ◽  
Exit Orifice

In this work we used deep-molding manufacture of three kinds to fabricate micro pressure-swirl atomizers to promote their performance, and a Phase Doppler Particle Analyzer (PDPA) to measure the characteristic distributions of the spray flow field of these atomizers. The deep-molding techniques were X-ray LIGA process, ICP-LIGA process (inductive coupling plasma etching), and injection molding LIGA process. Parameters of atomizers examined here include configuration of flow channel, diameter of exit orifice, the ratio of diameters of swirl chamber and discharge orifice, and the thickness of atomizer. Experimental results showed that the manufacturing process combining injection molding with electroplating had large yields and that the technique is highly reliable; enable manufacture of an atomizer at small cost and great quality. Moreover, these microatomizers are assembled well with other components and be readily applied. The results of PDPA diagnosis further revealed that the spray features are related with the design parameters of atomizer dimensions.

A Numerical Study of the Internal Flow in a Pressure Swirl Atomizer

2017 ◽  
Author(s):  
Weijia Qian ◽  
Xin Hui ◽  
Chi Zhang ◽  
Quanhong Xu ◽  
Yuzhen Lin ◽  
...  
Keyword(s):  
Internal Flow ◽  
Diameter Ratio ◽  
Geometric Parameters ◽  
Swirl Chamber ◽  
Discharge Parameters ◽  
Swirl Atomizer ◽  
Pressure Swirl ◽  
Pressure Swirl Atomizer ◽  
Exit Orifice ◽  
Length To Diameter Ratio

The internal flow and discharge parameters of a pressure swirl atomizer (PSA) are numerically investigated using a coupled Level-Set (LS)/Volume-of-Fluid (VOF) solver that combines the advantages of LS and algebraic VOF methods by maintaining the mass conservation and the interface sharpness simultaneously. Internal flow velocity profile and discharge parameters including discharge coefficient, film thickness, and spray cone angle are compared between simulation results and the experimental data that are available in the literature. A parametrical study is also performed to investigate the effects of the key geometric parameters of the PSA configuration on the discharge parameters. The geometric parameters studied are the length to diameter ratio of the swirl chamber, the length to diameter ratio of the exit orifice, the swirl chamber diameter to exit orifice diameter ratio, and the swirl chamber convergence angle.

scholarly journals Experimental Study of Spray Characteristics of Kerosene-Ethanol Blends from a Pressure-Swirl Nozzle

2018 ◽  
Vol 2018 ◽  
pp. 1-14 ◽  
Author(s):  
Tao Zhang ◽  
Bo Dong ◽  
Xun Zhou ◽  
Linan Guan ◽  
Weizhong Li ◽  
...  
Keyword(s):  
Discharge Coefficient ◽  
Cone Angle ◽  
Injection Pressure ◽  
Spray Characteristics ◽  
Spray Cone Angle ◽  
Spray Cone ◽  
Breakup Length ◽  
Ethanol Blends ◽  
Pressure Swirl ◽  
Spray Velocity

Partial replacement of kerosene by ethanol in a gas turbine is regarded as a good way to improve the spray quality and reduce the fossil energy consumption. The present work is aimed at studying the spray characteristics of kerosene-ethanol blends discharging from a pressure-swirl nozzle. The spray cone angle, discharge coefficient, breakup length, and velocity distribution are obtained by particle image velocimetry, while droplet size is acquired by particle/droplet imaging analysis. Kerosene, E10 (10% ethanol, 90% kerosene), E20 (20% ethanol, 80% kerosene), and E30 (30% ethanol, 70% kerosene) have been considered under the injection pressure of 0.1–1 MPa. The results show that as injection pressure is increased, the discharge coefficient and breakup length decrease, while the spray cone angle, drop size, and spray velocity increase. Meanwhile, the drop size decreases and the spray velocity increases with ethanol concentration when the injection pressure is lower than 0.8 MPa. However, the spray characteristics are not affected obviously by the ethanol concentration when the injection pressure exceeds 0.8 MPa. A relation to breakup length for kerosene-ethanol blends is obtained. The findings demonstrate that the adding of ethanol into kerosene can promote atomization performance.

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.

Influence of Ambient Air Pressure on Pressure-Swirl Atomization

1987 ◽  
Author(s):  
X. F. Wang ◽  
A. H. Lefebvre
Keyword(s):  
Drop Size ◽  
Cone Angle ◽  
Ambient Air ◽  
Air Pressure ◽  
Spray Angle ◽  
Flow Number ◽  
Spray Cone Angle ◽  
Spray Cone ◽  
Continuous Increase ◽  
Pressure Swirl

The spray characteristics of six simplex atomizers are examined in a pressure vessel using a standard light diffraction technique. Attention is focused on the effects of liquid properties, nozzle flow number, spray cone angle, and ambient air pressure on mean drop size and drop-size distribution. For all nozzles and all liquids it is found that continuous increase in air pressure above the normal atmospheric value causes the SMD to first increase up to a maximum value and then decline. An explanation for this characteristic is provided in terms of the measurement technique employed and the various competing influences on the overall atomization process. The basic effect of an increase in air pressure is to improve atomization, but this trend is opposed by contraction of the spray angle which reduces the relative velocity between the drops and the surrounding air, and also increases the possibility of droplet coalescence.

scholarly journals Positive association between progestins and the evolution of multiple fibroadenomas in 72 women

2020 ◽  
Vol 9 (6) ◽  
pp. 570-577
Author(s):  
Virginie Grouthier ◽  
Zeina Chakhtoura ◽  
Isabelle Tejedor ◽  
Yasmina Badachi ◽  
Vincent Goffin ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Cohort Study ◽  
Longitudinal Study ◽  
Natural History ◽  
Beneficial Effect ◽  
Positive Association ◽  
Breast Ultrasound ◽  
Benign Disease ◽  
Factors Influencing ◽  
The Us

Objective Multiple fibroadenomas (MFA) of the breast is a rare benign disease, thus its natural history is poorly understood. The aim of our study was to describe the radiological evolution of MFA and to evaluate the influence of different factors on this evolution. Methods This was a longitudinal cohort study. All patients included had two clinical and radiological assessments (breast ultrasound (US) and/or MRI) at least 5 years apart. Results Seventy-two women were followed for 7.6 ± 2.1 years. The radiological evolution showed a decrease or stability in the number of fibroadenomas (FA) in 26/44 cases on the MRI and in 38/64 cases on the US. There was a decrease of size in 35/44 cases on the MRI and in 53/64 cases on the US. An increase in the number of FAs was found in 18/44 cases in the MRI and 26/64 cases in the US with, for the majority, a decrease of size (19/26 by MRI and 16/18 by MRI). Older age at the first FA (P < 0.0001) and at the diagnosis of MFA (P < 0.0001), pregnancy (P = 0.003) and progestin use (P < 0.001), particularly lynestrenol (P < 0.0001), had a beneficial effect on the evolution of MFA. Conclusion This is the first longitudinal study describing women with MFA. The radiological evolution of MFA seamed favorable and similar to that expected for a single FA. We identified factors influencing the evolution of the disease, including progestin treatments such as lynestrenol, which could have a beneficial effect. Our cohort should be followed further in order to expand our knowledge of MFA, especially concerning the risk of breast cancer.

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