Internal Flow and Spray Characteristics of Pintle-Type Outwards Opening Piezo Injectors for Gasoline Direct-Injection Engines
Published April 16, 2007 by SAE International in United States
Annotation of this paper is available
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 results showed that the number of strings increased linearly, within the measured range, with liquid exit velocity and that the spray cone angle was smaller or larger than the nominal value depending on the attachment of air pockets to the cartridge or needle surfaces, respectively; these two distinct small and large cone angles were found to be dominant at low and high lifts. Increasing the flow rate further so that CN exceeds the critical value, gave rise to pockets of vapour that started to emerge in the nozzle seat region and disintegrated rapidly as they were convected towards the nozzle exit. The analysis of the near nozzle flow visualizations has shown the existence of air entrainment and cavitation as two different phenomena occurring under different operating conditions.
CitationMarchi, A., Nouri, J., Yan, Y., and Arcoumanis, C., "Internal Flow and Spray Characteristics of Pintle-Type Outwards Opening Piezo Injectors for Gasoline Direct-Injection Engines," SAE Technical Paper 2007-01-1406, 2007, https://doi.org/10.4271/2007-01-1406.
- Wirth, M., Zimmermann D., Friedfeldt R., Caine J., Schamel A., Davies M., Peirce G., Storch A., Ries-Müller K., Gansert K.P., Pilgram G., Ortmann R., Würfel G., Gerhardt J., A Cost Optimised Gasoline Spray Guided Direct Injection System for Improved Fuel Economy, Seminar on Fuel Economy and Engine Downsizing. Institution of Mechanical Engineers, One Birdcage Walk, London, 13 May 2004.
- Iwamoto Y., Noma K., Nakayama O., Yamauchi T. and Ando H., Development of gasoline direct injection engines. SAE Paper 970541, 1997.
- Nouri, J.M., Mitroglou N., Yan Y. and Arcoumanis C., Internal flow and cavitation in a multi-hole injector for gasoline direct injection engines. SAE Paper 2007-01-1405, 2007.
- Mitroglou, N., Nouri J.M., Yan Y., Gavaises M. and Arcoumanis C., Spray structure generated by multi-hole injectors for gasoline direct injection engines. SAE paper 2007-01-1417, 2007.
- Birth, I.G., Rechs M., Spicher U., and Bernhardt S., Experimental Investigation of the In-Nozzle Flow of Valve Covered Orifice Nozzle for Gasoline Direct Injection. 7PthP Int. Symp. Internal Combustion Diagnostics. 2006, pp. 59-78, Kurhaus Baden-Baden.
- Mitroglou N, Multihole Injectors for Direct-Injection Gasoline Engines, PhD Thesis, The City University, London, UK, 2006.
- Xu, M. and Markle L.E., CFD development of spray for an outwardly opening direct- injection gasoline injector., SAE Paper 980493, 1998.
- Shelby, M.H., VanDerWege B.A., and Hochgreb S., Early spray development in gasoline direct-injection spark-ignition engines. SAE 980160, 1998.
- Nouri, J.M. and Whitelaw J.H., Impingement of gasoline sprays on angled plates. Atomization and Sprays, 2006: 16(6): P. 705-726.
- Abo-Serie E., Arcoumanis C. and Gavaises M., Spray characterisation of swirl pressure atomizers for G-DI engines: phase doppler measurements. ILASS-Europe, Darmstadt, Germany, 11-13 Sept., 2000.
- Nouri J.M. and Whitelaw J.H., Effect of chamber pressure on the spray structure from a swirl pressure atomiser for direct injection gasoline engines. Proceedings ICOLAD 2002, London, 2002.
- Nouri J.M., Hamid M.A., Yan Y. and Arcoumanis C., Spray characterization of a piezo pintle-type injector for gasoline direct injection engines. Proceedings ICOLAD 2005, London, 2005.
- Mansour, A. and Chigier N., Dynamic behavior of liquid sheets. Phys. Fluids A, 1991: 3(12): p. 2971-2980.
- Arai, T. and Hashimoto H., Disintegration of a thin liquid sheet in a cocurrent gas stream. ICLASS-85, London, UK, 9-10 July, 1985.
- Cavalho, I.S., Heitoyr and Santos D., Liquid film disintegration regimes and proposed correlations, Int. J. of Multiphase flow, 2002: 28, p. 773-789.
- Nouri J.M., Abo-Serie E., Marchi A., Mitroglou N. and Arcoumanis C., Internal and near nozzle flow characteristics from an enlarge model of an outward opening gasoline direct injector. Proceedings ICOLAD 2005, London, 2005.
- Gavaises M., Tonini S., Marchi A., Theodorakakos A. and Bouris D., Modeling of internal and near-nozzle flow of a pintle-type outward opening piezo-injector. To be appear in J Engine Research, 2006.
- Tonini S. Multi-phase flow modelling of fuel injection processes in direct injection diesel and gasoline engines. PhD Thesis, The City University, London, UK, 2007.
- Marchi A., Pintle-type outwards opening piezo injectors for direct-injection gasoline engines, PhD Thesis in preparation, The City University, London, UK, 2007.