scholarly journals Prediction of the Initial Drop Size and Velocity Distribution in the Cold Cryogenic Spray

2020 ◽  
Vol 38 (3) ◽  
pp. 629-640
Author(s):  
Ahmed Abed Al-Kadhem Majhool ◽  
Noor Mohsin Jasim
Keyword(s):  
Velocity Distribution ◽  
Size Distribution ◽  
Liquid Nitrogen ◽  
Drop Size ◽  
Maximum Entropy Method ◽  
Cone Angle ◽  
Injection Pressure ◽  
Entropy Method ◽  
Spray Cone Angle ◽  
Spray Cone

The polydispersed nature of the spray is captured through the use of probability density functions based on the maximum entropy method to stand for the complete atomization characteristics of spray dynamics. The droplet and velocity size distributions are practical tools for the analysis of sprays cooling. The special benefit of the model is a Eulerian based which is less computationally intensive when compared to models that are based on the Lagrangian approach that tracks droplet parcel. The accuracy of using Lagrangian approach in polydispersed phase is always accurately less than Eulerian approach because it depends on the number of parcels while in Eulerian approach it depends on the proposed continuous distribution function. The main intent of the current work is to evaluate the capability of using the model for the initial predictions of the droplet size and velocity distribution for liquid nitrogen spray of solid-cone pressure swirl nozzle. The use of liquid injection pressure cases of up to 0.6MPa and spray cone angles of just 30◦ from three different sets of experimental data. The results being characterized are spray drop size distribution, liquid volume fraction and spray cone angle values. The unsteady analyses of the effect of injection pressure are studied on the cryogenic liquid nitrogen. The numerical results show that the maximum entropy method applies to liquid cryogenic spray and indicates that the model reacts correctly to changes in different injection pressures. Comparisons are also made with measured drop size distribution data that are reasonably captured and the spray cone angle is found to be in good agreement during initial and far-field spray angles.

Atomization Characteristics of Jatropha-Derived Alternative Aviation Fuels From Aircraft Engine Injector

2017 ◽  
Author(s):  
Ramachandran Sakthikumar ◽  
Deivandren Sivakumar ◽  
B. N. Raghunandan ◽  
John T. C. Hu
Keyword(s):  
Size Distribution ◽  
Drop Size ◽  
Cone Angle ◽  
Fuel Spray ◽  
Jet Fuels ◽  
Spray Characteristics ◽  
Spray Cone Angle ◽  
Spray Cone ◽  
Atmospheric Air ◽  
Atomization Characteristics

Search for potential alternative jet fuels is intensified in recent years to meet stringent environmental regulations imposed to tackle degraded air quality caused by fossil fuel combustion. The present study describes atomization characteristics of blends of jatropha-derived biofuel with conventional aviation kerosene (Jet A-1) discharging into ambient atmospheric air from a dual-orifice atomizer used in aircraft engines. The biofuel blends are characterized in detail and meet current ASTM D7566 specifications. The experiments are conducted by discharging fuel spray into quiescent atmospheric air in a fuel spray booth to measure spray characteristics such as fuel discharge behavior, spray cone angle, drop size distribution and spray patternation at six different flow conditions. The characteristics of spray cone angle are obtained by capturing images of spray and the measurements of spray drop size distribution are obtained using laser diffraction particle analyzer (LDPA). A mechanical patternator system comprising 144 measurement cells is used to deduce spray patternation at different location from the injector exit. A systematic comparison on the atomization characteristics between the sprays of biofuel blends and the 100% Jet A-1 is presented. The measured spray characteristics of jatropha-derived alternative jet fuels follow the trends obtained for Jet A-1 sprays satisfactorily both in qualitative and quantitative terms.

Axial and Radial Variation of Spray Characteristics of a Small-Scale Simplex Atomizer

2014 ◽  
Author(s):  
Muthuselvan Govindaraj ◽  
Muralidhara Halebidu Suryanarayana ◽  
Vinod Kumar Vyas ◽  
Jeyaseelan Rajendran ◽  
Rajeshwari Natarajan ◽  
...  
Keyword(s):  
Size Distribution ◽  
Droplet Size ◽  
Radial Direction ◽  
Cone Angle ◽  
Injection Pressure ◽  
Droplet Size Distribution ◽  
Axial Direction ◽  
Spray Cone Angle ◽  
Spray Cone ◽  
Injection Pressures

Simplex atomizer is widely used in the liquid fuel combustion devices in aerospace and power generation industries. An experimental work was conducted, to study variation of SMD and droplet size distribution along axial and radial directions of the spray for different injection pressures. Malvern spray analyzer is used in the present investigation. Four different atomizer configurations of increasing atomizer constant (K) are examined using water and kerosene. Spray cone angle is measured for different configurations at different injection pressures (up to 30 bar) using image processing technique. In the case of atomizer with lower K, spray cone angle continuously increases with injection pressure. In the case of atomizer with higher K, initially spray cone angle increases significantly, but remains almost constant after 16 bar. Variation of SMD and droplet size distribution along axial direction of the spray is compared between water and kerosene spray. SMD variation along the axial direction of spray clearly shows the continuous brakup of droplets along axial direction of the spray. In the case of water spray, SMD rapidly decreases along the axial direction up to 30 mm from the orifice exit, and gradually decreases up to 120 mm. In the case of kerosene spray, SMD rapidly decreases along the axial direction up to 40 mm from the orifice exit, after that SMD fluctuates along the axial direction up to 100 mm from the orifice exit. This fluctuation is due to evaporation of smaller droplets (50 microns) of kerosene. Span also continuously fluctuates after 40 mm from the orifice exit in the case of kerosene spray. Variation of SMD and droplet size distribution along radial direction of the spray is compared for different injection pressure and configurations of simplex atomizer. Increase in injection pressure, increases the disruptive aerodynamic force, which reduces the radial peak value of SMD and widens the radial profile. With decrease in atomizer constant (K), swirl strength inside the swirl chamber increases, which in turn increases the spray cone angle. SMD variation along the radial direction of spray showed more uniform droplet diameter distribution for lower atomizer constant (K) configurations. Reducing the atomizer constant improves the atomization quality more effectively than increasing the injection pressure.

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.

Numerical Simulation and Experiment of Atomization Field of Fan-Shaped Atomization Nozzle for Plant Protection UAV

2021 ◽  
Vol 14 ◽  
Author(s):  
Maohua Xiao ◽  
Yuanfang Zhao ◽  
Zhenmin Sun ◽  
Chaohui Liu ◽  
Tianpeng Zhang
Keyword(s):  
Numerical Simulation ◽  
Size Distribution ◽  
Droplet Size ◽  
Plant Protection ◽  
Cone Angle ◽  
Droplet Size Distribution ◽  
Droplet Velocity ◽  
Inlet Pressure ◽  
Spray Cone Angle ◽  
Spray Cone

Background: There are drift and volatilization of the droplets produced by the plant protection Unmanned Aerial Vehicle (UAV) under the influence of external wind speed and its flight speed. Objective: It studied the atomization characteristics of its fan-shaped atomizing nozzle under different inlet pressures and inner cavity diameters. Methods: For the start, the Realizable k-ε turbulence model, DPM discrete phase model and TAB breakup model are used to make a numerical simulation of the spray process of the nozzle. Then, the SIMPLE algorithm is used to obtain the droplet size distribution diagram of the nozzle atomization field. At last, the related test methods are used to study its atomization performance, and the changes of atomization angle and droplet velocity under different inlet pressures and inner cavity diameters and the distribution of droplet size are discussed. Results: The research results show that under the same inner cavity diameter, as the inlet pressure increases, the spray cone angle of the nozzle and the droplet velocity at the same distance from the nozzle increase. As the distance from the nozzle increases, the droplet velocity decreases gradually, the droplet size distribution moves to the direction of small diameter, and the droplets in the anti-drift droplet size area increase. Under the same inlet pressure, as the diameter of the inner cavity increases, the spray cone angle first increases and then decreases, and the droplet velocity at the same distance from the nozzle increases. As the distance from the nozzle increases, the droplet velocity decreases gradually, the droplet size distribution moves to the direction of large diameter, and the large size droplets increase, which cannot meet the anti-drift volatilization effect. Conclusion: Under the parameter set in this study, when the inlet pressure is 0.6MPa and the inner cavity diameter is 2mm, the atomization result is the best.

Characterizing Diesel Fuel Spray Cone Angle From Back-Scattered Imaging by Fitting Gaussian Profiles to Radial Spray Intensity Distributions

2012 ◽  
Vol 134 (6) ◽  
Author(s):  
Jaclyn E. Johnson ◽  
Jeffrey D. Naber ◽  
Seong-Young Lee
Keyword(s):  
Charge Density ◽  
Diesel Fuel ◽  
Curve Fitting ◽  
Cone Angle ◽  
Injection Pressure ◽  
Fuel Spray ◽  
Spray Cone Angle ◽  
Spray Cone ◽  
Gaussian Curve

Quantifying fuel spray properties including penetration, cone angle, and vaporization processes sheds light on fuel-air mixing phenomenon, which governs subsequent combustion and emissions formation in diesel engines. Accurate experimental determination of these spray properties is a challenge but imperative to validate computational fluid dynamic (CFD) models for combustion prediction. This study proposes a new threshold independent method for determination of spray cone angle when using Mie back-scattering optical diagnostics to visualize diesel sprays in an optically accessible constant volume vessel. Test conditions include the influence of charge density (17.6 and 34.9 kg/m3) at 1990 bar injection pressure, and the influence of injection pressure (990, 1370, and 1980 bar) at a charge density of 34.8 kg/m3 on diesel fuel spray formation from a multi-hole injector into nitrogen at a temperature of 100 °C. Conventional thresholding to convert an image to black and white for processing and determination of cone angle is threshold subjective. As an alternative, an image processing method was developed, which fits a Gaussian curve to the intensity distribution of the spray at radial spray cross-sections and uses the resulting parameters to define the spray edge and hence cone angle. This Gaussian curve fitting methodology is shown to provide a robust method for cone angle determination, accounting for reductions in intensity at the radial spray edge. Results are presented for non-vaporizing sprays using this Gaussian curve fitting method and compared to the conventional thresholding based method.

Effect of Injection Parameters on the Spray Characteristics of DME Fuel

2006 ◽  
Author(s):  
Bong Woo Ryu ◽  
Seung Hwan Bang ◽  
Hyun Kyu Suh ◽  
Chang Sik Lee
Keyword(s):  
Dimethyl Ether ◽  
Diesel Fuel ◽  
Cone Angle ◽  
Injection Pressure ◽  
Injection Rate ◽  
Spray Characteristics ◽  
Spray Cone Angle ◽  
Spray Cone ◽  
Injection Duration ◽  
Injection Parameters

The purpose of this study is to investigate the effect of injection parameters on the injection and spray characteristics of dimethyl ether and diesel fuel. In order to analyze the injection and spray characteristics of dimethyl ether and diesel fuel with employing high-pressure common-rail injection system, the injection characteristics such as injection delay, injection duration, and injection rate, spray cone angle and spray tip penetration was investigated by using the injection rate measuring system and the spray visualization system. In this work, the experiments of injection rate and spray visualization are performed at various injection parameters. It was found that injection quantity was decreased with the increase of injection pressure at the same energizing duration and injection pressure In the case of injection characteristics, dimethyl ether showed shorter of injection delay, longer injection duration and lower injected mass flow rate than diesel fuel in accordance with various energizing durations and injection pressures. Also, spray development of dimethyl ether had larger spray cone angle than that of diesel fuel at various injection pressures. Spray tip penetration was almost same development and tendency regardless of injection angles.

Experimental Study on Diesel Engine and Analysis the Spray Characteristics of Diesel and Biodiesel by Varying Injection Pressure

2014 ◽  
Vol 984-985 ◽  
pp. 932-937 ◽  
Author(s):  
Palani Raghu ◽  
M. Senthamil Selvan ◽  
K. Pitchandi ◽  
N. Nallusamy
Keyword(s):  
Experimental Study ◽  
Diesel Engine ◽  
Weber Number ◽  
Direct Injection ◽  
Cone Angle ◽  
Injection Pressure ◽  
Injection Velocity ◽  
Spray Characteristics ◽  
Spray Cone Angle ◽  
Spray Cone

— The spray characteristic of the injected fuel is mainly depends upon fuel injection pressure, temperature, ambient pressure, fuel viscosity and fuel density. An experimental study was conducted to examine the effect of injection pressure on the spray was injected into direct injection (DI) diesel engine in the atmospheric condition. In Diesel engine, the window of 20 mm diameter hole and the transparent quartz glass materials were used for visualizing spray characteristics of combustion chamber at right angle triangle position. The varying Injection pressure of 180 - 240 bar and the engine was hand cranked for conducting the experiments. Spray characteristics for Jatropha oil methyl ester (JOME) and diesel were studied experimentally. Spray tip penetration and spray cone angle were measured in a combustion chamber of Direct Injection diesel engine by employing high speed Digital camera using Mie Scattering Technique and ImageJ software. The study shows the JOME gives longer spray tip penetration and smaller spray cone angle than those of diesel fuels. The Spray breakup region (Reynolds number, Weber number), Injection velocity and Sauter Mean Diameter (SMD) were determined for diesel and JOME. SMD decreases for JOME than diesel and the Injection velocity, Reynolds Number, Weber Number Increases for JOME than diesel.

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.

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