Hydraulics Characteristics of a Mechanical Diesel Direct Injection System: The Influence of Diameter of High Pressure Pump’s Plunger, Number and Diameter of Injector Nozzles.
SAE-PP-00374
12/26/2023
- Content
- The diameter of the high pressure pump plunger, the number and diameter of injector nozzles play a crucial role in influencing hydraulic behaviors such as the start of injection, the pressure profiles developed in the high pressure line, needle lift, and injection rates in Diesel engines. These factors, in turn, significantly impact the distribution of fuel within the engine combustion chamber, fuel-air mixing, combustion quality, and the formation of emissions. However, as the plunger diameter and the number and diameter of nozzles vary, the system's complexity also rises, necessitating careful analysis, design, and calibration. Therefore, further examinations are critically essential to gain deeper insights into this topic. In this study, a high-speed shadowgraph system and a high-resolution pressure recording system were developed to capture the start of injection, spray structure, and pressure profiles in the high-pressure line. The fuel injection system under experimental investigation featured a 10mm plunger and a 7-nozzle injector with a nozzle diameter of 250µm. Additionally, GT-fuel simulation models were created to explore different plunger diameters and numbers and diameters of injector nozzles. These models were validated using the pressure profiles, fuel quantity, and start of injection timing obtained from the experiments. This approach can either individually analyse the influence of each parameter or assess their overall impact. The results indicate that an increase in plunger diameter from 10mm to 12mm advances the start of injection (SOI) to 30.7 degree from 31.4 degree of crankshaft angle. Furthermore, an increase in the number and/or diameter of nozzles results in a higher amount of fuel delivered per cycle. Overall, replacing a an injection system with 10mm plungers and injectors with 7x250µm nozzles by one featuring 12mm plungers and injectors having 8x300µm nozzles can increase the fuel delivery by 1.85 folds. This studying approach could be useful for practical applications, including boosting engines and/or designing more efficient fuel systems. Future investigations into the high-speed shadowgraph images captured in this study could offer additional insights into the Rayleigh-Taylor and Kelvin-Helmholtz models concerning the primary and secondary atomization processes.
- Citation
- Pham, P., Vu, T., Nguyen, K., Phung, D. et al., "Hydraulics Characteristics of a Mechanical Diesel Direct Injection System: The Influence of Diameter of High Pressure Pump’s Plunger, Number and Diameter of Injector Nozzles.," SAE MobilityRxiv™ Preprint, submitted December 26, 2023, https://doi.org/10.47953/SAE-PP-00374.