scholarly journals CFD simulations of the diesel jet primary atomization from a multihole injector

2017 ◽  
Author(s):  
Charalambos Chasos
Keyword(s):  
High Pressure ◽  
Nozzle Exit ◽  
Cone Angle ◽  
Injection Pressure ◽  
Liquid Jet ◽  
Spray Cone Angle ◽  
Two Phase ◽  
Spray Cone ◽  
Breakup Length ◽  
Jet Breakup

High pressure multi-hole diesel injectors are currently used in direct-injection common-rail diesel engines for the improvement of fuel injection and air/fuel mixing, and the overall engine performance. The resulting spray injection characteristics are dictated by the injector geometry and the injection conditions, as well as the ambient conditions into which the liquid is injected. The main objective of the present study was to design a high pressure multi-hole diesel injector and model the two-phase flow using the volume of fluid (VOF) method, in order to predict the initial liquid jet characteristics for various injection conditions. A computer aided design (CAD) software was employed for the design of the three-dimensional geometry of the assembly of the injector and the constant volume chamber into which the liquid jet emerges. A typical six-hole diesel injector geometry was modelled and the holes were symmetrically located around the periphery of the injector tip. The injector nozzle diameter and length were 0.2 mm and 1 mm, respectively, resulting in a ratio of nozzle orifice length over nozzle diameter L/D = 5. The commercial computational fluid dynamics (CFD) code STAR-CD was used for the generation of the computational mesh and for transient simulations with an Eulerian approach incorporating the VOF model for the two-phase flow and the Rayleigh model for the cavitation phenomenon. Three test cases for increasing injection pressure of diesel injection from the high pressure multi-hole diesel injector into high pressure and high temperature chamber conditions were investigated. From the injector simulations of the test cases, the nozzle exit velocity components were determined, along with the emerging liquid jet breakup length at the nozzle exit. Furthermore, the spray angle was estimated by the average radial displacement of the liquid jet and air mixture at the vicinity of the nozzle exit. The breakup length of the liquid jet and the spray cone angle which were determined from the simulations, were compared with the breakup length and cone angle estimated by empirical equations. From the simulations, it was found that cavitation takes place at the nozzle inlet for all the cases, and affects the fuel and air interaction at the upper area of the spray jet. Furthermore, the spray jet breakup length increases with elapsed time, and when the injection pressure increases both the breakup length and the spray cone angle increase.DOI: http://dx.doi.org/10.4995/ILASS2017.2017.5040

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.

Characteristics of Hollow Cone Swirl Spray at Various Nozzle Orifice Diameters

2012 ◽  
Vol 58 (2) ◽  
Author(s):  
A. Hussein ◽  
M. Hafiz ◽  
H. Rashid ◽  
A. Halim ◽  
W. Wisnoe ◽  
...  
Keyword(s):  
Discharge Coefficient ◽  
Cone Angle ◽  
Injection Pressure ◽  
Orifice Diameter ◽  
Hollow Cone ◽  
Spray Characteristics ◽  
Spray Cone Angle ◽  
Spray Cone ◽  
Nozzle Orifice ◽  
Breakup Length

An experimental work to investigate the swirl spray characteristics that emanates from hollow–cone and solid–cone spray simplex atomizers is presented. Main objective of the research is to investigate the spray characteristics, i.e. spray breakup length, discharge coefficient and spray cone angle at different nozzle orifice diameter and injection pressure. Discharge coefficient is almost uninfluenced by the operating Reynolds number. This test also reveals that both breakup length and spray cone angle increases as orifice diameter is increased. Higher injection pressure leads to shorter breakup length and wider spray cone angle.

Effect of geometric and operating parameters on the spray characteristics of an open-end swirl injector

2019 ◽  
Vol 233 (12) ◽  
pp. 4457-4467 ◽  
Author(s):  
Chen Chen ◽  
Yang Yang ◽  
Xiaorong Wang ◽  
Wenxian Tang
Keyword(s):  
Pressure Drop ◽  
Discharge Coefficient ◽  
Cone Angle ◽  
Injection Pressure ◽  
Operating Parameters ◽  
Spray Cone Angle ◽  
Spray Cone ◽  
Breakup Length ◽  
Swirl Chamber ◽  
Swirl Injector

To study the influence of geometric and operating parameters on the spray characteristics of an open-end swirl injector, seven injectors with different tangential inlet diameters ( D p) and injector length to injector orifice diameter ( L/D) ratios were tested and simulated. Using high-speed backlight, the evolution laws of liquid film thickness, discharge coefficient, spray cone angle, breakup length, and velocity distribution in the swirl chamber under different geometric and operating parameters were captured after unified image processing. Low-injection pressure drop is directly proportional to the discharge coefficient and the spray cone angle. When the injection pressure drop approaches or reaches a critical value of 0.4 MPa, the discharge coefficient and spray cone angle remain nearly constant with maximum fluctuations of 1% and 5%, respectively. With an increase in the geometric characteristic constant A, the liquid film thickness, discharge coefficient, breakup length, and velocity in the swirl chamber decrease, whereas the spray cone angle increases. As the viscous effect increases for increasing L/D, the discharge coefficient and breakup length increase, whereas the spray cone angle decreases. Based on experiment results, empirical formulas for the discharge coefficient, spray angle, and breakup length were put forward as reference for engineering applications, including the effect of the geometric and operating parameters.

On the Mechanism of Flashing Injection of Initially Subcooled Fuels

1984 ◽  
Vol 106 (1) ◽  
pp. 105-109 ◽  
Author(s):  
R. D. Oza
Keyword(s):  
Nozzle Exit ◽  
Cone Angle ◽  
Constant Volume ◽  
Spray Cone Angle ◽  
Two Phase ◽  
Spray Cone ◽  
Injector Nozzle ◽  
Exit Pressure ◽  
Flash Boiling

The mechanisms responsible for flash-boiling injection were investigated. Using an electromagnetic injector developed for this study, propane, methanol and Indolene were heated and injected into a constant-volume vessel. Two regimes of flash-boiling injection were identified. In the first regime, flash-boiling occurs within the injector nozzle without an increase in spray-cone angle. In the second regime, the nozzle exit pressure is sufficiently low that the two-phase compressible mixture created by flash-boiling within the injector nozzle is underexpanded at the nozzle exit and expands externally to increase the spray-cone angle.

Effect of Nanoparticles on the Fuel Properties and Spray Performance of Aviation Turbine Fuel

2016 ◽  
Vol 139 (3) ◽  
Author(s):  
Kumaran Kannaiyan ◽  
Kanjirakat Anoop ◽  
Reza Sadr
Keyword(s):  
Surface Tension ◽  
Physical Properties ◽  
Droplet Diameter ◽  
Cone Angle ◽  
Aviation Fuel ◽  
Alumina Nanoparticles ◽  
Spray Cone Angle ◽  
Spray Cone ◽  
Breakup Length ◽  
Sheet Breakup

The influence of nanoparticles' dispersion on the physical properties of aviation fuel and its spray performance has been investigated in this work. To this end, the conventional Jet A-1 aviation fuel and its mixtures with alumina nanoparticles (nanofuel) at different weight concentrations are investigated. The key fuel physical properties such as density, viscosity, and surface tension that are of importance to the fuel atomization process are measured for the base fuel and nanofuels. The macroscopic spray features like spray cone angle and sheet breakup length are determined using the shadowgraph technique. The microscopic spray characteristics such as droplet diameter, droplet velocity, and their distributions are also measured by employing phase Doppler anemometry (PDA) technique. The spray performance is measured at two nozzle injection pressures of 0.3 and 0.9 MPa. The results show that with the increase in nanoparticle concentrations in the base fuel, the fuel viscosity and density increase, whereas the surface tension decreases. On the spray performance, the liquid sheet breakup length decreases with increasing nanoparticle concentrations. Furthermore, the mean droplet diameters of nanofuel are found to be lower than those of the base fuel.

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.

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