Influence of diesel nozzle geometry on cavitation using eulerian multi-fluid method

Abstract

Dependent on automatically generated unstructured grids, a comprehensive computational fluid dynamics (CFD)numerical simulation is performed to analyze the influence of nozzle geometry on the internal flow characteristics of a multi-hole diesel injector with the multi-phase flow model based on Eulerian multi-fluid method. The diesel components in nozzle are considered as two continuous phases, diesel liquid and diesel vapor respectively. Considering that both of them are fully coupled and interpenetrated, separate sets of governing equations are established and solved for each phase. The geometric parameters mainly include the length and exit diameter of nozzle, the rounded radius at inlet of nozzle orifice and the angle between axis of injector and axis of nozzle orifice, and they are individually taken into account to analyze the impact on the cavitating flow in nozzle. The results show that the geometrical characteristics of nozzle have a strong influence on the volume fraction of diesel vapor in nozzle and the outlet flow velocity of injector. So cavitation in nozzle orifice should not be neglected for the in-cylinder fuel atomization process, especially for the primary break-up of liquid jet.

Keywords

diesel injection / cavitation / nozzle geometry / multi-phase flow / numerical simulation

References

[1] Haywood J. B. Internal Combustion Engine Fundamentals[M]. 1988, New York: McGraw-Hill Book Company 517-522.

[2] Arcoumanis C, Gavaises M, Roth H et al. Nozzle flow and spray characteristics from VCO diesel injector nozzles[ C]. In: Proceedings of Conference on Thermo-Fluid and Dynamic Processes in Diesel Engines. Thiesel, Valencia, Spain, 2002.

[3] Blessing M, König G, Krüger C et al. Analysis of flow and cavitation phenomena in diesel injection nozzles and its effects on spray and mixture formation[C]. In: SAE Paper, 2003-01-1358, 2003.

[4] Payri F., Bermúdez V., Payri R., et al. The Influence of cavitation on the internal flow and the spray characteristics in diesel injection nozzles[J]. Fuel, 2004, 83(4): 419-431.

[5] Gavaises M, Andriotis A. Cavitation inside multi-hole injectors for large diesel engines and its effects on the near-nozzle spray structure[C]. In: SAE Paper, 2006-01-1114, 2006.

[6] Lahey R T, Jr Drew D A. An analysis of two-phase flow and heat transfer using a multi-dimensional, multi-field, two-fluid computational fluid dynamics (CFD) model[C]. In: Proceedings of Japan/US Seminar on Two-Phase Flow Dynamics. Santa Barbara, California, 1999.

[7] Kunz R. F., Boger D. A., Stinebring D. R., et al. A coupled phasic exchange algorithm for three-dimensional multifield analysis of heated flows with mass transfer[J]. Computers and Fluids, 1998, 27(7): 741-768.

[8] Carrica P. M., Bonetto F., Drew D. A., et al. A polydispersed model for bubbly two-phase flow around a surface ship[J]. Multiphase Flow, 1999, 25(2): 257-305.

[9] Franklin R. E., McMillan J. Noise generation in cavitating flows, the submerged jet[J]. Journal of Fluids Engineering, 1984, 106(3): 336-341.

[10] Tatschl R, Künsberg Sarre C, Alajbegovic A et al. Diesel spray modeling including multidimensional cavitation nozzle flow effects[C]. In: Proc of ILASS Europe’ 2000. Darmstadt, Germany, 2000.

[11] Wang D. M., Issa R. I., Gosman A. D. Numerical prediction of dispersed bubbly flow in a sudden enlargement[C] Proceedings of the 1994 ASME Fluids Engineering Division Summer Meeting. Lake Tahoe, NV, USA, 1994, 185 141-148.

[12] Badock C, Wirth R, Fath A et al. The influence of hydro grinding on cavitation inside a diesel injection nozzle and primary break-up under unsteady pressure conditions[C]. In: Proc of ILASS-Europe’ 1999. Toulouse, France, 1999.

[13] Roth H. Experimental and Computational Investigation of Cavitation in Diesel Injector Nozzles[D]. University of London, 2004