Droplets size and velocity measurements in a spray from a common rail system for DI Diesel engines (Contributo in atti di convegno)

Type
Label
  • Droplets size and velocity measurements in a spray from a common rail system for DI Diesel engines (Contributo in atti di convegno) (literal)
Anno
  • 2008-01-01T00:00:00+01:00 (literal)
Alternative label
  • Allocca L., Alfuso S., Auriemma M., Valentino G. (2008)
    Droplets size and velocity measurements in a spray from a common rail system for DI Diesel engines
    in International Conference on Automotive Technologies – ICAT 2008, Istanbul (Turkey)
    (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#autori
  • Allocca L., Alfuso S., Auriemma M., Valentino G. (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#descrizioneSinteticaDelProdotto
  • This paper illustrates the results of an experimental investigation carried out on the liquid fuel spray from a multi-jet common rail injection system both under non evaporative and evaporative conditions. Tests have been taken using a 5 hole, 0.13 mm diameter, 150° spray angle, micro-sac nozzle having a flow rate of 270 cm³/30 sec@10 MPa. The aim of this work is the characterization of the structure of the fuel spray, in terms of global fuel behavior, liquid spray atomization as well velocity and size droplets dispersion. Images of spray evolution have been taken, under non evaporative conditions, injecting the fuel within quiescent inert gas, at different density, in a high-pressure optically-accessible cylindrical vessel with three large quartz windows. Under evaporative conditions, the experiments have been taken within a crank-case scavenged single-cylinder 2-stroke direct injection Diesel engine provided of optical accesses to the combustion chamber. It allows to study the fuel injection process under thermodynamic conditions similar to those currently reached in modern direct injection diesel engines. The air velocity field within the combustion chamber is low enough to assume that the fuel is injected at quiescent conditions, guaranteeing the same fluid flow conditions as those reproduced for tests within the vessel for non evaporative spray conditions. Liquid droplets size and axial velocity profiles have been estimated by applying the phase Doppler anemometry (PDA) technique spraying the fuel with a multiple injection strategy in an optically accessible vessel at ambient temperature and atmospheric pressure under quiescent conditions. PDA tests have been performed at different axial and radial distances from the injector nozzle in order to provide time resolved droplets size and axial velocity at different locations. Fuel droplets size and axial velocity distribution have provided detailed information on the spray morphology evolution, showing a jet structure composed by larger droplets during the transient needle opening and closure phases of the pilot, pre and main injection. During the steady state injection phase, instead, an homogeneous jet structure is highlighted close to the spray axis, with droplets diameter in a range of 1÷5 µm and axial velocity of about 100 m/s. Around the jet periphery an heterogeneous structure composed of droplets having a diameter up to 20 µm traveling at low axial velocity have been observed. (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#affiliazioni
  • Istituto Motori, CNR, Napoli, Italia. (literal)
Titolo
  • Droplets size and velocity measurements in a spray from a common rail system for DI Diesel engines (literal)
Abstract
  • This paper illustrates the results of an experimental investigation carried out on the liquid fuel spray from a multi-jet common rail injection system both under non evaporative and evaporative conditions. Tests have been taken using a 5 hole, 0.13 mm diameter, 150° spray angle, micro-sac nozzle having a flow rate of 270 cm³/30 sec@10 MPa. The aim of this work is the characterization of the structure of the fuel spray, in terms of global fuel behavior, liquid spray atomization as well velocity and size droplets dispersion. Images of spray evolution have been taken, under non evaporative conditions, injecting the fuel within quiescent inert gas, at different density, in a high-pressure optically-accessible cylindrical vessel with three large quartz windows. Under evaporative conditions, the experiments have been taken within a crank-case scavenged single-cylinder 2-stroke direct injection Diesel engine provided of optical accesses to the combustion chamber. It allows to study the fuel injection process under thermodynamic conditions similar to those currently reached in modern direct injection diesel engines. The air velocity field within the combustion chamber is low enough to assume that the fuel is injected at quiescent conditions, guaranteeing the same fluid flow conditions as those reproduced for tests within the vessel for non evaporative spray conditions. Liquid droplets size and axial velocity profiles have been estimated by applying the phase Doppler anemometry (PDA) technique spraying the fuel with a multiple injection strategy in an optically accessible vessel at ambient temperature and atmospheric pressure under quiescent conditions. PDA tests have been performed at different axial and radial distances from the injector nozzle in order to provide time resolved droplets size and axial velocity at different locations. Fuel droplets size and axial velocity distribution have provided detailed information on the spray morphology evolution, showing a jet structure composed by larger droplets during the transient needle opening and closure phases of the pilot, pre and main injection. During the steady state injection phase, instead, an homogeneous jet structure is highlighted close to the spray axis, with droplets diameter in a range of 1÷5 µm and axial velocity of about 100 m/s. Around the jet periphery an heterogeneous structure composed of droplets having a diameter up to 20 µm traveling at low axial velocity have been observed. (literal)
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