Spray collapse resistance of GDI injectors with different hole structures under flash boiling conditions. (1st April 2023)

• Record Type: Journal Article
• Authors: Chang, Mengzhao; Kim, Huijun; Zhou, Bo; Park, Suhan
• Is Part Of: Energy. Volume 268(2023)
• Publication Date: 2023-04-01
• Subjects: Gasoline direct injection -- Injector design parameters -- Flash boiling -- Macroscopic spray characteristics -- Spray collapse; Power resources -- Periodicals; Power (Mechanics) -- Periodicals; Energy consumption -- Periodicals; 333.7905
• DOI: 10.1016/j.energy.2023.126689
• Languages: English
• ISSNs: 0360-5442

Abstract

Abstract: The purpose of this study was to compare the spray collapse resistance and explore the spray collapse mechanism of GDI injectors with different hole structures to provide a theoretical basis for the optimal design of injectors in addition to the clean combustion of internal combustion engines. Herein, a shadowgraph visualization system was used to record the macroscopic spray of the different injectors, with MATLAB used to obtain quantitative data from the spray images. The effects of hole length-to-diameter (L/D), hole shape, and step hole diameter (Ds) on the spray collapse characteristics were analyzed quantitatively. Finally, the nozzle near-field spray of the injectors and the pressure distribution below the injectors were simulated using CFD to analyze the spray collapse mechanism. The results indicated that an increase in L/D did significantly affect collapse point (the superheat degree at the onset of spray collapse). Among the injectors with straight, reverse taper, tapered and tapered step holes, the collapse point of the tapered step injector is about 10 °C lower than that of other injectors. Among the three structural features of the injector holes, the step hole diameter had the greatest influence on the spray collapse point. By reducing step hole diameter, the spray collapse point was delayed by approximately 22 °C, because under flash boiling conditions, the expanded spray plume occupies almost the entire space of the step hole. A small step-hole diameter limits the expansion of spray plumes and the interaction between them, thus improving the resistance of the spray to collapse. Graphical abstract: Image 1 Highlights: A quantitative index for judging the spray collapse starting point was developed. Step hole diameter is the most important factor affecting spray collapse resistance. Larger step hole leads to wider spray plumes and lower pressure distribution, resulting in easier spray collapse.