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In the present study, the flow inside a real size Diesel fuel injector nozzle was modeled and analyzed under different boundary conditions using ANSYS-Fluent software. A validation was performed by comparing our numerical results with previous experimental data for a rectangular shape nozzle. Schnerr-Sauer cavitation model, which was selected for this study, was also validated. Two-equation k-ε turbulence model was selected since it had good agreement with experimental data. To reduce the computing time, due to symmetry of this nozzle, only one-sixth of this nozzle was modeled. Our present six-hole Diesel injector nozzle was modeled with different needle lifts including 30 μm, 100 μm and 250 μm. Effects of different needle lifts on mass flow rate, discharge coefficient and length of cavitation were evaluated comprehensively. Three different fuels including one Diesel fuel and two bio-Diesel fuels were also included in these numerical simulations. Behavior of these fuels was investigated for different needle lifts and pressure differences. For comparing the results, discharge coefficient, mass flow rate and length of cavitation region were compared under different boundary conditions and for several fuel types. The extreme temperature spike at the center of an imploding cavitation bubble was also analyzed as a function of time and initial bubble size.
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Micro-reactor design optimization and manufacturing for studying high temperature unimolecular decomposition of large molecules
Low residence time flow reactors (≤100 μs), when combined with photoionization mass spectrometry or matrix isolation/infrared spectroscopy, have the capability to directly probe the elementary pyrolytic reaction mechanism for various fuels. A qualitative analysis of flow inside these reactors (straight tubes approximately 1mm inner diameter and 3cm in length made of SiC) suggests pressure and velocity significantly change along the length of the reactor. This presents a challenge in determining actual flow conditions within the reactor making it complicated to establish conditions at which pyrolytic chemistry occurs. Computational and experimental testing have been used to optimize a new reactor geometry to control the flow profiles by adding a constriction at one end of the reactor. The nozzle has been shown computationally to stabilize fluid flow within the reactor. A review of available manufacturing processes and coating techniques to incorporate this constriction are presented along with the final processes selected. Further computational and experimental evaluations are discussed to highlight the performance of this new nozzle. The novel design of the micro-reactor will assist researchers in carrying out fundamental kinetic measurements of short residence time pyrolytic reactions of fuels influencing the creation of more efficient fuels and in sustainable engine technology.
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- Award ID(s):
- 1834656
- PAR ID:
- 10104529
- Date Published:
- Journal Name:
- 11th U. S. National Combustion Meeting
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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