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Yan, Y.
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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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Digital-Imaging-Based Analysis and Characterization of Diesel Sprays

Delphi Diesel Systems Ltd.-G. Greeves, S. Smith
University of Greenwich-J. Shao, Y. Yan
  • Technical Paper
  • 2003-04-0080
Published 2002-11-26 by Institution of Mechanical Engineers in United Kingdom
This paper presents the recent progress in the development of digital imaging and image processing techniques for the quantitative characterization of diesel sprays. An optically accessible, constant volume chamber was configured to allow photographic imaging of sprays, which were generated from a six-hole nozzle in a non-evaporating and pressurized environment. A high-resolution CCD camera and a flash light source were used to capture the spray images. Dedicated digital image processing algorithms have been developed to quantify the fundamental, characteristic parameters of the sprays. An application of the algorithms to the characterization of diesel sprays from a VCO nozzle is also presented and discussed.

Fuzzy measurement of perception for edge extraction

University of Teesside-D. Hong, T. Sarkodie-Gyan, A. W. Campbell, Y. Yan
  • Technical Paper
  • 1996-25-0386
Published 1996-06-03 by ISATA - Dusseldorf Trade Fair in United Kingdom
In this paper, a method is proposed to measure the human perception using fuzzy sets theory, so that a set of thresholds can be determined properly to guide an edge tracking execution. First, the principle of an efficient edge-marking and linking algorithms is briefly introduced based on the edge tracking technique. A set of edge models is presented. The cost functions for evaluating the edge paths are not only defined according to the change of local gradient magnitude but also according to the change of local gradient direction. A set of thresholds is defined by taking advantage of the histogram of edge-enhanced images to determine the start and the end of the edge tracking. Therefore, irrespective of the variation within the intensity levels of images, the algorithm will always gain the best edge extraction. The fuzzy sets concept is used to combine the human linguistic language into the operation of the determination of edge contrast to the background. A more acceptable interface is established according to the human visual perception. The new algorithm has been…

Pseudo-three-dimensional, vision-based measurement system of pistons

University of Teesside-D. Hong, A. W. Campbell, Y. Yan, T. Sarkodie-Gyan
  • Technical Paper
  • 1995-25-0209
Published 1995-09-18 by ISATA - Dusseldorf Trade Fair in United Kingdom
In this paper, we describe a range-measuring method to identify various different pistons by projecting a laser line onto the crowns of the pistons. There exist a number of similar piston types with very slight differences but with the same overall diameter such that it is readily possible to fit the incorrect piston to an engine. Differences between a number of families of similar pistons are found in obvious features such as gudgeon pin diameter and position, etc. Within a family, the differences are more subtle and may be simply a change in the maximum depth of the bowl in the crown of the piston. A pseudo- three-dimensional, vision-based measurement system is designed to confirm the identity of the piston just after it has been fitted to the engine assembly. The measurement system consists of a laser line generator, a CCD camera and a PC. Because of the symmetry of the piston crown, only one image of the crown is needed to reconstruct the 3D image of the crown and to determine the quality and…