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Nouri, J. M.
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Spray Structure Generated by Multi-Hole Injectors for Gasoline Direct-Injection Engines

The City University, London, UK-N. Mitroglou, J. M. Nouri, Y. Yan, M. Gavaises, C. Arcoumanis
Published 2007-04-16 by SAE International in United States
The performance of multi-hole injectors designed for use in second-generation direct-injection gasoline engines has been characterised in a constant-volume chamber. Two types of multi-hole injector have been used: the first has 11 holes, with one hole on the axis of the injector and the rest around the axis at 30 degrees apart, and the second has 6 asymmetric holes located around the nozzle axis. Measurements of droplet axial and radial velocity components and their diameter were obtained using a 2-D phase Doppler anemometer (PDA) at injection pressures up to 120 bar, chamber pressures from atmospheric to 8 bar, and ambient temperatures. Complementary spray visualisation made use of a pulsed light and a CCD camera synchronised with the injection process.Comparison of the results between the two injectors has allowed quantification of the influence of the number of holes and nozzle length-to-diameter ratio on the spray structure and spray tip penetration, droplet velocity and size distribution as a function of injection and chamber pressures of relevance to gasoline passenger cars.
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Internal Flow and Cavitation in a Multi-Hole Injector for Gasoline Direct-Injection Engines

The City University, London, UK-J. M. Nouri, N. Mitroglou, Y. Yan, C. Arcoumanis
Published 2007-04-16 by SAE International in United States
A transparent enlarged model of a six-hole injector used in the development of emerging gasoline direct-injection engines was manufactured with full optical access. The working fluid was water circulating through the injector nozzle under steady-state flow conditions at different flow rates, pressures and needle positions. Simultaneous matching of the Reynolds and cavitation numbers has allowed direct comparison between the cavitation regimes present in real-size and enlarged nozzles. The experimental results from the model injector, as part of a research programme into second-generation direct-injection spark-ignition engines, are presented and discussed. The main objective of this investigation was to characterise the cavitation process in the sac volume and nozzle holes under different operating conditions. This has been achieved by visualizing the nozzle cavitation structures in two planes simultaneously using two synchronised high-speed cameras.Imaging of the flow inside the injector nozzle identified the formation of three different types of cavitation as a function of the cavitation number, CN. The first is needle cavitation, formed randomly at low CN (0.5-0.7) in the vicinity of the needle, which penetrates into…
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Internal Flow and Spray Characteristics of Pintle-Type Outwards Opening Piezo Injectors for Gasoline Direct-Injection Engines

The City University, London, UK-A. Marchi, J. M. Nouri, Y. Yan, C. Arcoumanis
Published 2007-04-16 by SAE International in United States
The near nozzle exit flow and spray structure generated by an enlarged model of a second generation pintle type outwards opening injector have been investigated under steady flow conditions as a function of flow-rate and needle lift. A high resolution CCD camera and high-speed video camera have been employed in this study to obtain high-magnification images of the internal nozzle exit flow in order to identify the origin of string ligaments/droplets formation at the nozzle exit. The images of the flow around the nozzle seat area showed clearly that air was entrained from outside into the nozzle seat area under certain flow operating conditions (low cavitation number, CN); the formed air pockets inside the annular nozzle proved to be the main cause of the breaking of the fuel liquid film into strings as it emerged from the nozzle with a structure consisting of alternating thin and thick liquid filaments. As the flow rate increased, the air pockets were suppressed, reduced in size and pushed towards the exit of the nozzle resulting in a smoother spray.The…
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Analysis of the Flow in the Nozzle of a Vertical Multi-Hole Diesel Engine Injector

Ford Motor Company Ltd.-E. Abdul-Wahab, Roy W. Horrocks
Imperial College of Science, Technology & Medicine-C. Arcoumanis, M. Gavaises, J. M. Nouri
Published 1998-02-23 by SAE International in United States
An enlarged transparent model of a six-hole vertical diesel injector has been manufactured in order to allow flow measurements inside the sac volume and the injection holes to be obtained using a combination of laser Doppler velocimetry (LDV) and the refractive index matching technique under steady state conditions. The measurement points were concentrated in the sac volume close to the entrance of the injection holes as well as inside them on a vertical plane passing through the axis of two injection holes for two different needle lifts. The velocity flow field was characterized in terms of the mean velocity and the turbulent intensity. The results revealed that, under certain conditions, cavitation may occur in the recirculation zone formed at the entrance to the hole since the pressure in this region can reach the value of the vapor pressure of the flowing liquid; this was found to strongly depend on the needle lift and eccentricity. Images taken with a CCD and a high-speed camera have identified differences on the onset and the development of the cavitation…
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Measurement of the Internal Fluid Flow in a Diesel Injector Using Refractive Index Matching

Imperial College of Science, Technology and Medicine-C. Arcoumanis, J. M. Nouri
Lucas Powertrain Systems-R. J. Andrews
  • Technical Paper
  • 924188
Published 1992-04-14 by Institution of Mechanical Engineers in United Kingdom
An enlarged acrylic model of a production diesel fuel injection nozzle was used in a steady flow rig to allow flow velocity measurements to be obtained by laser doppler velocimetry in critical areas of the nozzle. Optical access into the flow passages was achieved by using, instead of gas oil, a mixture of hydrocarbon fuels which at a given mixture ratio, temperature and laser wavelength match the refractive index of the acrylic nozzle, thus making possible the quantitative characterization of the nozzle internal flow.
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Coolant Flow in the Cylinder Head/Block of the Ford 2.5L DI Diesel Engine

Dept. of Mechanical Engineering Imperial College of Science, Technology and Medicine London, England-C. Arcoumanis, J. M. Nouri, J. H. Whitelaw
Diesel Engineering Ford Motor Co., Ltd. England-G. Cook, D. M. Foulkes
Published 1991-02-01 by SAE International in United States
Local measurements of the mean and rms velocities have been obtained by laser Doppler velocimetry in the coolant passages of a transparent model of a Ford 2.5L diesel cylinder head and block at a steady flowrate of 6.83 × 10-4 M3/s. The simulation of the coolant fluid by a mixture of hydrocarbon fluids at a predetermined constant temperature allowed accurate matching of the refractive index to that of the acrylic model, thus providing optical access for LDV measurements of the internal flow in sensitive areas where cooling is essential to prevent metal-fatigue failure. The results were obtained in sufficient detail to allow further validation of CFD coolant flow models.
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