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 The Two-Phase Conical Swirl Atomizers: Spray Characteristics

Energies ◽  
2020 ◽  
Vol 13 (13) ◽  
pp. 3416 ◽  
Author(s):  
Marek Ochowiak ◽  
Andżelika Krupińska ◽  
Sylwia Włodarczak ◽  
Magdalena Matuszak ◽  
Małgorzata Markowska ◽  
...  
Keyword(s):  
Flow Rate ◽  
Discharge Coefficient ◽  
Experimental Studies ◽  
Central Area ◽  
Spray Angle ◽  
Sauter Mean Diameter ◽  
Spray Characteristics ◽  
Two Phase ◽  
Mean Diameter ◽  
The Impact

This paper presents the results of experimental studies on two-phase conical swirl atomizers. The impact of various atomizer geometries and different operational parameters of the atomization process on the spray characteristics was investigated. The influence of the mixing chamber height HS to diameter DS ratio and the volumetric flow rates of liquid and gas on the discharge coefficient values, spray angle, droplet size expressed by Sauter mean diameter D32, volumetric and radial distributions of droplet diameters in the spray stream were determined. The analysis of results showed that the discharge coefficient values depend on the Reynolds number for liquid and gas and the atomizer geometry. The spray angle increases as the flow rate of liquid and gas increases depending on the applied atomizer construction. The Sauter mean diameter value is correlated with the geometric dimensions of the atomizer swirl chamber. The rapid increase in D32 occurs after exceeding the value HS/DS ≈ 3. The Sauter mean diameter also depends on the operating parameters. A central area of stream is filled with smaller sized droplets as the gas flow rate increases.

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.

Numerical Simulation of Internal Flow and Spray of Liquid Phase LPG (Liquefied Petroleum Gas) Injection

2008 ◽  
Author(s):  
Boyan Xu ◽  
Yunliang Qi ◽  
Shaoli Cai ◽  
Deqiang Geng
Keyword(s):  
Numerical Simulation ◽  
Liquid Phase ◽  
Initial Conditions ◽  
Gas Injection ◽  
Injection Pressure ◽  
Internal Flow ◽  
Liquefied Petroleum Gas ◽  
Sauter Mean Diameter ◽  
Mean Diameter ◽  
Nozzle Geometries

Cavitation and flashing formed inside and outside of an injector, respectively, have significant effect on liquid phase LPG (Liquefied Petroleum Gas) injection. Numerical simulations of internal flow of the liquid phase LPG inside different injector nozzles were performed using the FIRE CFD code. The results showed that the cavitation always occurred at the inlet corner of the nozzle with negative pressure and higher velocity regardless the nozzle geometries. The relationships between vapor void fraction at the exit of the nozzle and injection pressure were also investigated for different nozzle geometries. The spray of the liquid phase LPG was further simulated by using the results of the internal flow as initial conditions. During the simulation of the spray, the effect of superheat degree on evaporation was considered and a modified evaporation equation was employed. The comparison of the simulation with experimental results showed that, with the injection pressure increasing, spray tip penetration increased but SMD (Sauter mean diameter) decreased.

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.

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.

Effect of Flow Pulsation on Transport and Secondary Atomization of a Polydisperse Evaporating Spray

2014 ◽  
Author(s):  
Pallab S. Mahapatra ◽  
Mahesh V. Panchagnula ◽  
Achintya Mukhopadhyay
Keyword(s):  
Drop Size ◽  
Plug Flow ◽  
Pulsation Frequency ◽  
Sauter Mean Diameter ◽  
Atomization Process ◽  
Population Balance Modeling ◽  
Air Stream ◽  
Linear Behaviour ◽  
Acoustic Instabilities ◽  
Evaporating Spray

In the present work a 1D plug flow evaporator has been considered to study the evaporation, atomization and transport of polydisperse droplets in a pulsating air stream. The pulsation in the air flow is very common in the real combustor due to the thermo acoustic instabilities. Population balance modeling approach is used to study the continuous evaporation and atomization process. An Eulerian-Eulerian multiphase framework is used to capture the polydispersity of the system. For the evaporation the fixed drop size methodology of the D2 law has been used whereas, for the atomization the conservation of mass has been considered during the breakage. The objective of this work is to study the pulsation frequency on the dispersion of droplets without and with presence of the evaporation and atomization rate. From the results, clustering of particles in different locations has been identified. The variation of Sauter Mean Diameter (SMD) is presented and the non-linear behaviour has been identified in the process.

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