Influence of nozzle geometry on spray and combustion characteristics related to large two-stroke engine fuel injection systems

FUEL

卷:294

Article

Balz, R.^1,2  Bernardasci, G.²  von Rotz, B.²  Sedarsky, D.¹ 

[1] Chalmers Univ Technol, Dept Mech & Maritime Sci, Gothenburg, Sweden

[2] Winterthur Gas & Diesel Ltd, Winterthur, Switzerland

关键词: Cavitation;    Spray;    Marine diesel engine;    Fuel injection;    Combustion;   

DOI  :  10.1016/j.fuel.2021.120455

来源: Elsevier

【 摘 要 】

As emission regulations for large two-stroke marine Diesel engines increase as well, the manufacturers face similar problems as small-sized engine builders. The fuel injection, spray formation and subsequent combustion process remain among the main drivers for emissions of direct-injection, compression-ignition internal combustion engines. Since the fuel injection nozzle design of large two-stroke marine Diesel engines differs significantly, not only in size but especially regarding their non-symmetricity and eccentrical orifice arrangement, compared with four-stroke engines, the bulk of research available related to this topic is very limited. To further deepen the understanding of how in-nozzle cavitation flow during the fuel injection process affects the combustion behaviour in large two-stroke marine Diesel engines, transparent nozzle geometries have been used to link the cavitation phenomena with spray and combustion characteristics. A total of six single-orifice nozzles based on the original five-orifice nozzle design of large two-stroke marine Diesel fuel injectors, with and without hydro-erosive grinding, have been experimentally investigated under realistic engine conditions using highspeed optical measurement techniques and a unique constant-volume spray chamber that geometrically represents a combustion chamber of a large two-stroke marine Diesel engine at top dead centre. The spray morphology and combustion results reveal significant differences between the non- and hydroerosive ground nozzle geometries. While the standard and angled nozzle versions remain similar, the eccentrical nozzle with its distinctive in-nozzle swirl cavitation pattern behaves differently, leading to a very reliable start of ignition behaviour and extreme wide spray angle.

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