Post on 23-Feb-2016
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ECN
Gasoline Spray (Spray G)Topic 3.5 Internal flow modeling
Ron Grover (GM)
Spray G – Internal Flow Modeling
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Outline• Model setup and assumptions• Mass flow calculations• Nozzle exit velocity field• Summary and discussion
Overview
Research Questions• Can we actually get results?• What is a representative discharge coefficient injector?• What is the flow field exiting the injector?• What is the deviation in mass flow per hole?
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ECN• Fluid Solver HRMFoam (c/o UMass)• Turbulence k-epsilon• Assumptions Submerged Fluid, Incompressible,
Isenthalpic• Meshing 414,000 cells • Mesh Topology Polyhedral (STAR-CCM+)
2 layer extrusion on wall• Needle Motion None. Fixed maximum lift 45 µm
Cell size ~ 30 – 65 µm
Nozzle cell size ~ 20-30 µm
Spray G – Model Setup
L/D ~ 1 (nozzle)
L/D ~ 1.2 (c-bore)
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Predicted CD ~ 0.50 Cv ~ 0.73 CA ~ 0.69
Spray G – Run to Steady State
GM Measurement CD ~ 0.52
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ECN Spray G – Internal Flow Results
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Counterbore Exit
Time=2.8ms
Nozzle Hole Exit
Spray G – Velocity Cut Planes
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Hole % Flow CD Deviation (%)1 12.0 0.50 -3.65
2 12.2 0.50 -2.10
3 12.5 0.52 0.34
4 14.1 0.58 13.01
5 11.4 0.47 -8.96
6 11.5 0.47 -8.30
7 14.5 0.60 16.10
8 11.7 0.48 -6.44
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Time=2.8ms
Discharge Coefficient Per Hole
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Hole % Flow CD Deviation (%)1 12.0 0.50 -3.65
2 12.2 0.50 -2.10
3 12.5 0.52 0.34
4 14.1 0.58 13.015 11.4 0.47 -8.966 11.5 0.47 -8.307 14.5 0.60 16.108 11.7 0.48 -6.44
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Discharge Coefficient Per Hole
Time=2.8ms
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Initial Findings• CFD calculations show that deficit in discharge coefficient is
equally attributed to both a velocity and area deficit• The velocity distribution per hole is biased towards the side of
the hole closest to the injector axis• An instantaneous snapshot of discharge coefficient per hole
shows variation; a finding that requires further investigation
Call for Additional Contributions!• Solicit various modeling approaches (1-fluid, 2-component, etc. )• Increased mesh resolution• Effect of plenum size• Needle motion effects• Internal-to-external nozzle flow coupling
Summary & Discussion Points
Thank-You