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March 16, 2018, 08:03 |
Oil Jet Stability
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#1 |
New Member
Daniel Gasper
Join Date: Dec 2017
Posts: 1
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Hello,
i am student from Germany and i am working on my graduation work. My English is pretty bad, but i have a problem and cant find a solution. So i decided to do my best and try to explain what i am doing, maybe someone can help me. From researches i know there are 3 different states of Oil-Jet-Break up. The Jet forms droplets or sprays, depending on the reynolds-number and weber-number. (depending on viscosity, velocity, surface-tension etc.) Heres my problem, i try to simulate it (plane) with the boundary conditions of the engine, and the Oil-Jet does nothing like that. Its just a laminar Jet right into the cooling-channel. The Jet doesent break up. I uploaded different picture showing my Problem and my input data for the simulation. I dont think that my solution is right and the Jet dont break up. Maybe someone understands my Problem and can help me. I dont know witch parameter i should change.. i tryed diffrent velocitys, pressure, mass-flows and it wont effect the result. But changes should affect the result. It always looks like a Laminar Jet (left Picture in the Figure) and what i am expecting is a turbulent flow (right picture in the Figure) My Setup: (Attachment) Nodes (73005) Elements (71904) Fluent: Models (Multiphase) Volume Fraction Parameters: Explicit Volume Fraction Cutoff: 1e-06 Courant Number: 0.25 Implicit Body Force Interface Modeling: Sharp Energy - Off Viscous - Standard k-e, Standard Wall Function 2D-Space: Axisymmetric Materials: engine-oil: Density: 889 kg/m^3 Viscosity: 0.013337 kg/m-s Air: Density: 1.225 kg/m^3 Viscosity: 1.7894e-05 kg/m-s Interaction: Surface Tension constant: 0.25 Boundary Conditions: Inlet: pressure-inlet: 450000 Pa Turbulent Intensity 0.5% Hydraulic Diameter 0.003 Outlet: pressure-outlet: Backflow Turbulent Intensity: 8% Backflow Turbulent Length Scale: 0.3 m Backflow Volume Fraction: 0 Methods: PISO Skewness Correction: 0 Neighbor Correction: 3 Skewness-Neighbor Coupling: no Least Squares Cell Based Pressure: PRESTO! Momentum: Second Order Upwind Volume Fraction: Geo-Reconstruct Turbulent Kinetic Energy: Second Order Upwind Turbulent Dissipation Rate: Second Order Upwind Transient Formulation: First Order Implicit Controls: Pressure: 0.9 Density: 0.5 Body Forces: 0.5 Momentum: 0.5 Turbulent Kinetic Energy: 0.5 Turbulent Dissipation Rate: 0.9 Turbulent Viscosity: 0.9 Initialization Methods: Standard Compute from: Inlet Patch: Phase oil Volume Fraction Value 0 Gradient Adaption: Method: Iso-Value Volume Fraction Phase: oil Refine Threshold: 0.3 Coarsen Threshold: 3 Run: Time Stepping Method: Variable Global Courant Number: 0.8 Ending Time: 0.5 Minimum Time Step Size: 1e-09 Maximum Time Step Size: 1e-06 I appreciate every help i can get. Thanks a lot! Daniel |
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