Low-temperature combustion (LTC) strategies for diesel engines are of increasing interest because of their potential to significantly reduce particulate matter (PM) and nitrogen oxide (NOx) emissions. LTC with late fuel injection further offers the benefit of combustion phasing control because ignition is closely coupled to the fuel injection event. But with a short ignition-delay, fuel jet mixing processes must be rapid to achieve adequate premixing before ignition. In the current study, mixing and pollutant formation of late-injection LTC are studied in a single-cylinder, direct-injection, optically accessible heavy-duty diesel engine using three laser-based imaging diagnostics. Simultaneous planar laser-induced fluorescence of the hydroxyl radical (OH) and combined formaldehyde (H2CO) and polycyclic aromatic hydrocarbons (PAH) are compared with vapor-fuel concentration measurements from a non-combusting condition. Through comparative analysis of OH, H2CO, and PAH fluorescence, mixtures are identified as either fuel-lean, fuel-rich, or of intermediate stoichiometries.The impacts of combustion chamber design on incylinder mixing processes are explored by comparing three piston bowl diameters of 60%, 70% and 80% of the cylinder bore. The data show that piston-bowl diameter influences in-cylinder mixing and pollutant formation processes by altering jet-jet and jet-wall interactions. When the fuel jets impinge on the bowl wall prior to ignition, adjacent jets merge, forming fuel-rich regions where soot formation occurs. By using a larger diameter bowl, wall impingement prior to ignition is reduced and delayed, and mixtures are leaner throughout the jet. However, a greater fraction of the jet becomes too lean for complete combustion. By using a smaller diameter bowl, a strong jet-wall interaction pushes the fuel-rich jet-jet interaction regions into the center of the chamber, where mixtures are predominantly lean. This reduces net soot formation and displaces fuel-lean regions of otherwise incomplete combustion into the combusting regions near the bowl wall.


    Access

    Check access

    Check availability in my library

    Order at Subito €


    Export, share and cite



    Title :

    Effects of Piston Bowl Geometry on Mixture Development and Late-Injection Low-Temperature Combustion in a Heavy-Duty Diesel Engine


    Additional title:

    Sae Int. J. Engines


    Contributors:

    Conference:

    SAE World Congress & Exhibition ; 2008


    Published in:

    Publication date :

    2008-04-14


    Size :

    25 pages




    Type of media :

    Conference paper


    Type of material :

    Print


    Language :

    English





    Piston Bowl Geometry Effects on Combustion Development in a High-Speed Light-Duty Diesel Engine

    Kurtz, Eric / Perini, Federico / Zha, Kan et al. | SAE Technical Papers | 2019


    Optimization of Piston Bowl Geometry for a Low Emission Heavy-Duty Diesel Engine

    Guo, Zexian / He, Xin / Pei, Yuanjiang et al. | British Library Conference Proceedings | 2020


    Optimization of Piston Bowl Geometry for a Low Emission Heavy-Duty Diesel Engine

    Wang, Boyuan / Chang, Chen-Teng / Wang, Peng et al. | SAE Technical Papers | 2020


    Optimization of Piston Bowl Geometry for a Low Emission Heavy-Duty Diesel Engine

    Guo, Zexian / He, Xin / Pei, Yuanjiang et al. | British Library Conference Proceedings | 2020