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.

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 Analysis of the macrostructure of the fuel spray atomized with marine engine injector

2019 ◽  
Vol 179 (4) ◽  
pp. 80-85
Author(s):  
Joanna GROCHOWALSKA
Keyword(s):  
Cone Angle ◽  
Combustion Process ◽  
Constant Volume ◽  
Fuel Spray ◽  
Spray Cone Angle ◽  
Spray Cone ◽  
Marine Engine ◽  
Spray Tip Penetration ◽  
Optical Visualization ◽  
Constant Volume Chamber

One of the main problem influencing the combustion process in the cylinder of the marine engine is an fuel spray phenomena. The parameters describing the shape of the fuel spray are named macro parameters. This article presents the research results of the macrostructure parameters of the fuel spray atomized with the marine engine injector. The research were carried out by optical visualization measurement method of Mie scattering. The diameter of nozzle injector was 0.375 mm and L/D coefficient 8.3. In these research were considered different parameters of injection opening pressures and backpressures in the constant volume chamber. Generally conlusions are: the opening pressure influence on maximum spray tip penetration, spray cone angle and influence on speed of the injected fuel. The increase of backpressure into the constant volume chamber causes the reduction of spray tip penetration and the increase of the spray cone angle.

scholarly journals Performance and Emission Characteristics of Cashewnut Shell Liquid as Alternate Fuel with Five Hole Nozzle

2019 ◽  
Vol 8 (6S3) ◽  
pp. 2117-2119
Keyword(s):  
Cone Angle ◽  
Cashew Nut Shell Liquid ◽  
Spray Cone Angle ◽  
Spray Cone ◽  
Performance And Emission ◽  
Cashew Nut ◽  
Injector Nozzle ◽  
The People ◽  
Alternative Sources ◽  
Cashew Nut Shell

Natural elements such as plants, vegetables , and reusable materials are the main sources of biodiesel. Harmful chemicals that can affect the environment in a worse condition is not produced by this biodiesel which affects the atmosphere. Alternative sources for energy has been searched by the people in an increasing manner in the recent days. The paper deals with the use of Cashew nut shell liquid as an alternative fuel which is obtained from cashew industry as a by product. Fuel is injected into the engine as a fine sprayer through the injection nozzle. To spray diesel fuel in the cylinder an injector nozzle is fixed at the top with lot of holes. The injector nozzle is used to mix the fuel and airand is sprayed at a high pressure. As the spray cone angle is large in the multi hole injector nozzles diesel can be sprayed in a better way to obtain a uniform mixture.

Flash Boiling Spray Simulation Based on Void Fraction and Superheat Controlling

2015 ◽  
Vol 737 ◽  
pp. 289-295
Author(s):  
Hong Yuan Ding ◽  
Peng Deng ◽  
Xu Yao Mao ◽  
Chao Wu
Keyword(s):  
Void Fraction ◽  
Cone Angle ◽  
Transition Process ◽  
Development Trend ◽  
Zone Method ◽  
Spray Cone Angle ◽  
Spray Cone ◽  
Simulation Based ◽  
Flash Boiling ◽  
High Superheat

A new flash boiling spray model whose atomization criterion based on the void fraction and superheat while evaporation model based on the dual-zone method is established to simulate the flashing sprays. The model function is implemented in KIVA program. Flash boiling spray model predicts spray penetration and spray cone angle and its development trend, in good agreement with the experimental results. The model has a good capability in simulating flash sprays at low superheat conditions, which breakup is controlled by void fraction, as well as high superheat transition process. It can also predict flare flashing sprays to some extent at higher superheat conditions.

scholarly journals Experimental Characterization of Two-Phase Aerated Liquid Ethanol and Jet A Spray Flames

2020 ◽  
Vol 10 (19) ◽  
pp. 6950
Author(s):  
Cary Smith ◽  
Mark Gragston ◽  
Yue Wu ◽  
Zhili Zhang
Keyword(s):  
Cone Angle ◽  
Mie Scattering ◽  
Aviation Fuel ◽  
Flame Height ◽  
Size Spectrum ◽  
Spray Cone Angle ◽  
Two Phase ◽  
Spray Cone ◽  
Spray Flames ◽  
Fuel Jet

This work provides an analysis of an air-assisted atomizing nebulizer’s spray characteristics and combustion behaviors via application of various diagnostics. Two-phase far-field flows and flames of liquid ethanol and practical aviation fuel Jet A were characterized for the droplet distributions, fuel concentrations, and flame dynamics by shadowgraph, Mie scattering, and chemiluminescence imaging of CH*, C2*, and CO2*. Both instantaneous and time-averaged measurements of the two-phase flow and flame characteristics were obtained. Shadowgraphs were used to measure the probability distribution of the droplet diameters. Mie scattering was used to map fuel concentration and obtain the liquid spray cone angles. Estimates of the lifted flame height were obtained by both shadowgraph and Mie scattering, which were verified by the chemiluminescence images. The effect of flow rates on parameters such as flow characteristic, spray cone angle, and drop size spectrum were quantitatively characterized for both ethanol and practical aviation fuel Jet A.

Method of Identifying Injector Coking From the Spray Field of Mechanical and CRDi Injectors Using Intensity of Scattered Light

2017 ◽  
Vol 140 (2) ◽  
Author(s):  
Ronith Stanly ◽  
Gopakumar Parameswaran ◽  
Bibin Sagaram
Keyword(s):  
Scattered Light ◽  
Near Field ◽  
Cone Angle ◽  
Angle Measurement ◽  
Field Region ◽  
Fuel System ◽  
Spray Cone Angle ◽  
Spray Cone ◽  
Cleaning Procedure ◽  
Spray Field

The influence of injector coking deposits on the spray field of single-hole mechanical port fuel injectors and multihole common rail direct injection (CRDi) injectors was studied using light scattering technique coupled with image processing and analysis. Instead of employing the traditional accelerated coking process to study injector spray field deterioration, in-service injectors were selected and cleaned using a commercial fuel system cleaning procedure. Variation in atomization characteristics of coked and cleaned injectors were observed based on the spatial distribution of fine, medium, and coarse droplets in the near-field region of the injector spray zone and analyzed as a function of the intensity of scattered light. The improvement in the atomization perceived by this method was compared with traditional techniques like spray cone angle measurement, speed characterization of spray jets, and weight reduction of injector nozzles and needles. It was observed that after the fuel system cleaning procedure, a reduction in the number of coarse droplets in the near-field region and an increase in the number of medium and finely sized droplets was observed, suggesting better atomization of fuel in the near field spray zone.

Experimental and Numerical Studies of Diesel Spray Evaporation and Combustion in a Gas Turbine Matrix Burner

2009 ◽  
Author(s):  
Dieter Bohn ◽  
James F. Willie ◽  
Nils Ohlendorf
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Combustion Instability ◽  
Cone Angle ◽  
Spray Angle ◽  
Test Rig ◽  
Spray Cone Angle ◽  
Spray Cone ◽  
Flow Simulations ◽  
Air Inlet

Lean gas turbine combustion instability and control is currently a subject of interest for many researchers. The motivation for running gas turbines lean is to reduce NOx emissions. For this reason gas turbine combustors are being design using the Lean Premixed Prevaporized (LPP) concept. In this concept, the liquid fuel must first be atomized, vaporized and thoroughly premixed with the oxidizer before it enters the combustion chamber. One problem that is associated with running gas turbines lean and premixed is that they are prone to combustion instability. The matrix burner test rig at the Institute of Steam and Gas Turbines at the RWTH Aachen University is no exception. This matrix burner is suitable for simulating the conditions prevailing in stationary gas turbines. Till now this burner could handle only gaseous fuel injection. It is important for gas turbines in operation to be able to handle both gaseous and liquid fuels though. This paper reports the modification of this test rig in order for it to be able to handle both gaseous and liquid primary fuels. Many design issues like the number and position of injectors, the spray angle, nozzle type, droplet size distribution, etc. were considered. Starting with the determination of the spray cone angle from measurements, CFD was used in the initial design to determine the optimum position and number of injectors from cold flow simulations. This was followed by hot flow simulations to determine the dynamic behavior of the flame first without any forcing at the air inlet and with forcing at the air inlet. The effect of the forcing on the atomization is determined and discussed.

Effects of Fuel Nozzle Condition on Gas Turbine Combustion Chamber Exit Temperature Distributions

2010 ◽  
Author(s):  
Kristen Bishop ◽  
William Allan
Keyword(s):  
Combustion Chamber ◽  
Ambient Pressure ◽  
Cone Angle ◽  
Operating Conditions ◽  
Spray Cone Angle ◽  
Mixing Processes ◽  
Spray Cone ◽  
Temperature Distributions ◽  
Fuel Nozzle ◽  
Exit Temperature

The effects of fuel nozzle condition on the temperature distributions experienced by the nozzle guide vanes have been investigated using an optical patternator. Average spray cone angle, symmetry, and fuel streaks were quantified. An ambient pressure and temperature combustion chamber test rig was used to capture exit temperature distributions and to determine the pattern factor. The rig tests matched representative engine operating conditions by matching Mach number, equivalence ratio, and fuel droplet size. It was observed that very small deviations (± 10° in spray cone angle) from a nominal distribution in the fuel nozzle spray pattern correlated to increases in pattern factor, apparently due to a degradation of mixing processes, which created larger regions of very high temperature core flow and smaller regions of cooler temperatures within the combustion chamber exit plane. The spray cone angle had the most measureable influence while the effects of spray roundness and streak intensity had slightly less influence. Comparisons were made with published studies conducted on the combustion chamber geometry, and recommendations were made for fuel nozzle inspections.

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.

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