Commenced in January 2007
Frequency: Monthly
Edition: International
Paper Count: 31903
Effect of Needle Height on Discharge Coefficient and Cavitation Number

Authors: Azadeh Yazdi, Mohammadreza Nezamirad, Sepideh Amirahmadian, Nasim Sabetpour, Amirmasoud Hamedi

Abstract:

Cavitation inside diesel injector nozzle is investigated using Reynolds-Stress-Navier stokes equations. Schnerr-Sauer cavitation model is used for modeling cavitation inside diesel injector nozzle. The carrying fluid utilized in the current study is diesel fuel. The flow is verified at the beginning by comparing with the previous experimental data and it was found that K-Epsilon turbulent model could lead to a better accuracy comparing to K-Omega turbulent model. Moreover, mass flow rate obtained numerically is compared with the experimental value and discrepancy was found to be less than 5% - which shows the accuracy of the current results. Finally, a real-size four-hole nozzle is investigated and the flow inside it is visualized based on velocity profile, discharge coefficient and cavitation number. It was found that the mesh density could be reduced significantly by utilizing periodic boundary condition. Velocity contour at the mid nozzle showed that maximum value of velocity occurs at the end of the needle before entering the orifice area. Last but not least, at the same boundary conditions, when different needle heights were utilized, it was found that as needle height increases with an increase in cavitation number, discharge coefficient increases, while the mentioned increases is more tangible at smaller values of needle heights.

Keywords: cavitation, diesel fuel, CFD, real size nozzle, mass flow rate

Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 293

References:


[1] Som, S., et al., Investigation of Nozzle Flow and Cavitation Characteristics in a Diesel Injector. Journal of Engineering for Gas Turbines and Power-Transactions of the Asme, 2010. 132(4).
[2] Shneider, M. N. and M. Pekker, Classic cavitation. Liquid Dielectrics in an Inhomogeneous Pulsed Electric Field: Dynamics, Cavitation and Related Phenomena, 2nd Edition, 2020.
[3] Stuppioni, U., et al., Computational Fluid Dynamics Modeling of Gaseous Cavitation in Lubricating Vane Pumps: An Approach Based on Dimensional Analysis. Journal of Fluids Engineering-Transactions of the Asme, 2020. 142(7).
[4] Sun, T. Z., et al., Numerical Investigation of Unsteady Cavitation Dynamics over a NACA66 Hydrofoil near a Free Surface. Journal of Marine Science and Engineering, 2020. 8(5).
[5] Sagar, H. J., et al., Experimental and numerical investigation of damage on an aluminum surface by single-bubble cavitation. Materials Performance and Characterization, 2018. 7(5): p. 985-1003.
[6] Zeidi, S. and M. Mahdi, Investigation the effects of injection pressure and compressibility and nozzle entry in diesel injector nozzle's flow. Journal of Applied and Computational Mechanics, 2015. 1(2): p. 83-94.
[7] Zeidi, S. M. J. and M. Mahdi, Evaluation of the physical forces exerted on a spherical bubble inside the nozzle in a cavitating flow with an Eulerian/Lagrangian approach. European Journal of Physics, 2015. 36(6).
[8] Payri, F., et al., The influence of cavitation on the internal flow and the spray characteristics in diesel injection nozzles. Fuel, 2004. 83(4-5): p. 419-431.
[9] Payri, R., et al., Critical cavitation number determination in diesel injection nozzles. Experimental Techniques, 2004. 28(3): p. 49-52.
[10] Jia, M., et al., Numerical simulation of cavitation in the conical-spray nozzle for diesel premixed charge compression ignition engines. Fuel, 2011. 90(8): p. 2652-2661.
[11] Giannadakis, E., M. Gavaises, and C. Arcoumanis, Modelling of cavitation in diesel injector nozzles. Journal of Fluid Mechanics, 2008. 616: p. 153-193.
[12] Kubo, M., T. Araki, and S. Kimura, Internal flow analysis of nozzles for DI diesel engines using a cavitation model. Jsae Review, 2003. 24(3): p. 255-261.
[13] Reid, B., et al., An optical comparison of the cavitation characteristics of diesel and bio-diesel blends in a true-scale nozzle geometry. International Journal of Engine Research, 2013. 14(6): p. 622-629.
[14] Bastawissi, H.A.E. and M. Elkelawy, Computational Evaluation of Nozzle Flow and Cavitation Characteristics in a Diesel Injector. Sae International Journal of Engines, 2012. 5(4): p. 1605-1616.
[15] Andriotis, A. and M. Gavaises, Influence of Vortex Flow and Cavitation on near-Nozzle Diesel Spray Dispersion Angle. Atomization and Sprays, 2009. 19(3): p. 247-261.
[16] Andriotis, A., M. Gavaises, and C. Arcoumanis, Vortex flow and cavitation in diesel injector nozzles. Journal of Fluid Mechanics, 2008. 610: p. 195-215.
[17] Winklhofer, E., et al. Comprehensive hydraulic and flow field documentation in model throttle experiments under cavitation conditions. in Proceedings of the ILASS-Europe conference, Zurich. 2001.
[18] Schnerr, G. H. and J. Sauer. Physical and numerical modeling of unsteady cavitation dynamics. in Fourth international conference on multiphase flow. 2001. ICMF New Orleans