TECHNICAL PAPERS: Internal Combustion Engines

Coupled Simulations of Nozzle Flow, Primary Fuel Jet Breakup, and Spray Formation

[+] Author and Article Information
Eberhard von Berg, Wilfried Edelbauer, Reinhard Tatschl

Advanced Simulation Technologies, AVL List GmbH, Hans-List Platz-1, A-8020 Graz, Austria

Ales Alajbegovic1

 AVL Powertrain Engineering, Inc., 47519 Halyard Drive, Plymouth, MI 48170-2438

Martin Volmajer, Breda Kegl

Faculty of Mechanical Engineering, University of Maribor, Slovenia

Lionel C. Ganippa2

Department of Thermo and Fluid Dynamics, Chalmers University of Technology, Gothenburg, Sweden


Current address: General Dynamics, Ann Arbor, MI 48105.


Current address: Department of Applied Physics, University of Nijmegen, Netherlands.

J. Eng. Gas Turbines Power 127(4), 897-908 (Apr 16, 2004) (12 pages) doi:10.1115/1.1914803 History: Received June 13, 2003; Revised April 16, 2004

Presented are two approaches for coupled simulations of the injector flow with spray formation. In the first approach the two-fluid model is used within the injector for the cavitating flow. A primary breakup model is then applied at the nozzle orifice where it is coupled with the standard discrete droplet model. In the second approach the Eulerian multi-fluid model is applied for both the nozzle and spray regions. The developed primary breakup model, used in both approaches, is based on locally resolved properties of the cavitating nozzle flow across the orifice cross section. The model provides the initial droplet size and velocity distribution for the droplet parcels released from the surface of a coherent liquid core. The major feature of the predictions obtained with the model is a remarkable asymmetry of the spray. This asymmetry is in agreement with the recent observations at Chalmers University where they performed experiments using a transparent model scaled-up injector. The described model has been implemented into AVL FIRE computational fluid dynamics code which was used to obtain all the presented results.

Copyright © 2005 by American Society of Mechanical Engineers
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Figure 1

Asymmetric distribution of flow properties in the nozzle orifice. Liquid phase velocity, vapor volume fraction, liquid phase turbulence kinetic energy (TKE), and turbulence energy dissipation (TED) for Chalmers case 4.

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Figure 2

Nozzle flow calculation grid and auxiliary grid as well as sketch of projection method to determine parcel release positions

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Figure 3

Basic features of cavitating nozzle flow simulation for conditions taken from Chalmers case 4

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Figure 4

Spatial structure of cavitating nozzle flow inside the injection hole. (a) vapor volume fraction (white: vapor; black: liquid), (b) liquid velocity (light colored: high; dark: low values), (c) liquid turbulent kinetic energy (light colored: high; dark: low values).

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Figure 5

Sensitivity of cavitation mass exchange model with respect to condensation reduction and turbulent pressure correction. Upper row: injection pressure 0.185 MPa, lower row: injection pressure 0.2 MPa. (a) and (d): reference case; (b) and (e): increased condensation reduction parameter; (c) and (f): activation of turbulent pressure correction (with CE=1).

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Figure 6

Spray shape, droplet sizes, and velocities for Chalmers case 5 (front view)

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Figure 7

Spray shape, droplet sizes, and velocities for Chalmers case 5 (side view)

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Figure 8

Phase volume fractions in nozzle and spray region for Diesel injection. (a) continuous liquid phase with cavitation near the wall, (b) breakup of continuous liquid phase, (c) dispersed droplet phases and total spray droplet volume fraction.

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Figure 9

The dispersion of the spray under different cavitating conditions. The bright regions show the location of vapor. Shown are snapshots from cases 1 to 5, denoted here by letters (a)–(e) in the upper row the enlarged view of the cavitating flow inside the nozzle hole is shown (diameter 5 mm). The second row shows the injector flow and spray together.

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Figure 10

Distribution of vapor volume fraction inside the injection hole (white: pure vapor; black: pure liquid)

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Figure 11

Spray shape calculated for Chalmers experiments with increasing pressure. Pictures (a)–(e) corresponding to experimental cases 1–5

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Figure 12

Nozzle flow and spray for case 1 at Δp=0.1MPa

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Figure 13

Nozzle flow and spray for case 2 at Δp=0.12MPa

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Figure 14

Nozzle flow and spray for case 3 at Δp=0.15MPa

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Figure 15

Nozzle flow and spray for case 4 at Δp=0.185MPa

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Figure 16

Nozzle flow and spray for case 5 at Δp=0.21MPa

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Figure 17

Phase volume fraction distributions from coupled calculation with the multi-fluid model for Chalmers case 4

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Figure 18

Total liquid volume fraction and continuous liquid phase velocity vectors in the orifice plane: (a) side view; (b) cut through orifice plane; (c) cut through symmetry plane of the injection hole



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