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Internal Nozzle Flow Simulations of the ECN Spray C Injector under Realistic Operating Conditions
- Hengjie Guo - Argonne National Laboratory ,
- Roberto Torelli - Argonne National Laboratory ,
- Abian Bautista Rodriguez - Argonne National Laboratory ,
- Aniket Tekawade - Argonne National Laboratory ,
- Brandon Sforzo - Argonne National Laboratory ,
- Christopher Powell - Argonne National Laboratory ,
- Sibendu Som - Argonne National Laboratory
ISSN: 2641-9645, e-ISSN: 2641-9645
Published April 14, 2020 by SAE International in United States
Citation: Guo, H., Torelli, R., Bautista Rodriguez, A., Tekawade, A. et al., "Internal Nozzle Flow Simulations of the ECN Spray C Injector under Realistic Operating Conditions," SAE Int. J. Adv. & Curr. Prac. in Mobility 2(4):2229-2240, 2020, https://doi.org/10.4271/2020-01-1154.
In this study, three-dimensional large eddy simulations were performed to study the internal nozzle flow of the ECN Spray C diesel injector. Realistic nozzle geometry, full needle motion, and internal flow imaging data obtained from X-ray measurements were employed to initialize and validate the CFD model. The influence of injection pressure and fuel properties were investigated, and the effect of mesh size was discussed. The results agreed well with the experimental data of mass flow rate and correctly captured the flow structures inside the orifice. Simulations showed that the pressure drop near the sharp orifice inlet triggered flow separation, resulting in the ingestion of ambient gas into the orifice via a phenomenon known as hydraulic flip. At higher injection pressure, the pressure drop was more significant as the liquid momentum increased and the stream inertia was less prone to change its direction. Two fuels were tested in both experiments and simulations, namely iso-octane and n-dodecane. With the former, the gas species in the low-pressure region consisted of both fuel vapor and non-condensable gas. With n-dodecane, due to its low saturation pressure, fuel vapor was practically absent. Furthermore, it was found that fuel cavitation might not be the only phenomenon able to trigger flow separation, as “pseudo-cavitation” caused by non-condensable gas expansion played a similar role in promoting the conditions that led the flow to detach from the wall. Finally, it was found that a minimum mesh size of 10 μm within the orifice was sufficient to ensure the main flow features were captured. However, it was shown that finer meshes allowed for better resolution of the near-wall gas layer, resulting in more flow features to be resolved.