THERMAL SCIENCE

International Scientific Journal

Thermal Science - Online First

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Optical experiments of string cavitation in diesel injector tapered nozzles

ABSTRACT
Flow inside the diesel nozzle is crucial to spray, combustion and emissions. This work aimed to improve the understanding of effects of internal fuel flow on diesel spray, especially the special string cavitating flow. Optical experiments were employed for characterizing the formation of string cavitation inside the transparent scaled-up tapered diesel orifices. Simultaneously, the corresponding evolution of spray cone angles were obtained. Results show that there were two origins of the string cavitation, which were originated from inlet and outlet of the orifice, respectively. Moreover, there were two typical development processes of the string cavitation between hole and hole, which were defined as type-A and type-B string cavitation. Furthermore, effects of string cavitation were analyzed: it could trigger the geometry-induced cavitation and make a sharp increase of spray cone angle. Finally, the relationships between the occurrence regularity of string cavitation, the needle lift and the injection pressure were revealed by comparison of different needle lifts and different injection pressures.
KEYWORDS
PAPER SUBMITTED: 2018-04-05
PAPER REVISED: 2018-12-06
PAPER ACCEPTED: 2018-12-11
PUBLISHED ONLINE: 2019-01-13
DOI REFERENCE: https://doi.org/10.2298/TSCI180405005G
REFERENCES
  1. Tamaki N, Shimizu M, Nishida K, Hiroyasu H. Effects of cavitation and internal flow on atomization of a liquid jet. Atomization & Sprays. 1998;8:179-97.
  2. Sou A, Biçer B, Tomiyama A. Numerical simulation of incipient cavitation flow in a nozzle of fuel injector. Computers & Fluids. 2014;103:42-8.
  3. Biçer B, Sou A. Application of the improved cavitation model to turbulent cavitating flow in fuel injector nozzle. Applied Mathematical Modelling. 2016;40:4712-26.
  4. Gavaises M, Roth H, Arcoumanis C. Cavitation Initiation, Its Development and Link with Flow Turbulence in Diesel Injector Nozzles. Sae International Journal of Engines. 2002;111:561-80.
  5. Guo G, He Z, Zhang Z, Duan L, Guan W, Duan X, et al. Visual experimental investigations of string cavitation and residual bubbles in the diesel nozzle and effects on initial spray structures. International Journal of Engine Research. 2018:1468087418791061.
  6. Kato M, Kano H, Date K, Oya T, Niizuma K. Flow Analysis in Nozzle Hole in Consideration of Cavitation. International Congress & Exposition1997.
  7. Payri F, Bermúdez V, Payri R, Salvador FJ. The influence of cavitation on the internal flow and the spray characteristics in diesel injection nozzles. Fuel. 2004;83:419-31.
  8. He Z, Guo G, Tao X, Zhong W, Leng X, Wang Q. Study of the effect of nozzle hole shape on internal flow and spray characteristics. International Communications in Heat and Mass Transfer. 2016;71:1-8.
  9. Som S, Ramirez AI, Longman DE, Aggarwal SK. Effect of nozzle orifice geometry on spray, combustion, and emission characteristics under diesel engine conditions .. Fuel. 2011;90:1267-76.
  10. Afzal H, Arcoumanis C, Gavaises M, Kampanis N. Internal flow in diesel injector nozzles-modelling and experiments. Imeche1999.
  11. Soteriou C, Andrews R, Smith M. Further studies of cavitation and atomization in diesel injection. SAE Technical Paper; 1999.
  12. Chahine GL, Duraiswami R. Dynamical Interactions in a Multi-Bubble Cloud. Journal of Fluids Engineering. 1992;114:680.
  13. Chahine GL, Kalumuck KM, Hsiao CT. Simulation of surface piercing body coupled response to nderwater bubble dynamics utilizing 3DYNAFS, a three-dimensional BEM code. Computational Mechanics. 2003;32:319-26.
  14. Gavaises M, Arcoumanis C. Vortex flow and cavitation in diesel injector nozzles. Journal of Fluid Mechanics. 2008;610:195-215.
  15. Gavaises M, C A, H F, M B. Cavitation in Real-Size Multi-Hole Diesel Injector Nozzles. Sae International Journal of Engines. 2000;109.
  16. Watanabe H, Nishikori M, Hayashi T, Suzuki M, Kakehashi N, Ikemoto M. Visualization analysis of relationship between vortex flow and cavitation behavior in diesel nozzle. International Journal of Engine Research. 2014;16:5-12.
  17. Duke D, Swantek A, Tilocco Z, Kastengren A, Fezzaa K, Neroorkar K, et al. X-ray imaging of cavitation in diesel injectors. SAE international Journal of Engines. 2014;7:1003-16.
  18. Zhang X, Moon S, Gao J, Dufresne EM, Fezzaa K, Wang J. Experimental study on the effect of nozzle hole-to-hole angle on the near-field spray of diesel injector using fast X-ray phase-contrast imaging. Fuel. 2016;185:142-50.