CFD Untersuchung von im Ölbad rotierenden Zahnrädern mit Fluent CFD investigation of rotating gears in oil with Fluent

Paul Illg, Alexander Berg, Dmitrij Neufeld John Deere GmbH & Co. KG, Mannheim

P. Illg, A. Berg, D. Neufeld 2 ANSYS Conference & 33rd CADFEM Users' Meeting

June 24 – 26, 2015, Messe Bremen |

Content

John Deere – Today

Background & Objectives

Verification Procedure

Results

Conclusion

P. Illg, A. Berg, D. Neufeld 3 ANSYS Conference & 33rd CADFEM Users' Meeting

June 24 – 26, 2015, Messe Bremen |

Content

John Deere – Today

Background & Objectives

Verification Procedure

Results

Conclusion

P. Illg, A. Berg, D. Neufeld 4 ANSYS Conference & 33rd CADFEM Users' Meeting

June 24 – 26, 2015, Messe Bremen |

John Deere Factory Mannheim and Bruchsal

Producing AG equipment since 1867

over 1.6 million tractors since 1921

2/3 of overall German tractor production

70 to 210 hp tractors (97/68/EC)

4,005 employees at the Mannheim site

1,375 employees at the Bruchsal site

Biggest John Deere factory outside of North America

P. Illg, A. Berg, D. Neufeld 5 ANSYS Conference & 33rd CADFEM Users' Meeting

June 24 – 26, 2015, Messe Bremen |

6R Transmission - Power of Choice

PowrQuad Plus

AutoQuad Plus

DirectDrive AutoPowr

P. Illg, A. Berg, D. Neufeld 6 ANSYS Conference & 33rd CADFEM Users' Meeting

June 24 – 26, 2015, Messe Bremen |

Content

John Deere – Today

Background & Objectives

Verification Procedure

Results

Conclusion

P. Illg, A. Berg, D. Neufeld 7 ANSYS Conference & 33rd CADFEM Users' Meeting

June 24 – 26, 2015, Messe Bremen |

Background & Objectives Model Order Reduction: From Tractor to Component Test Rig

Tractor

Lots of different systems & circuits

Different focus & analysis goals

Gearbox

Lots of different - gear pairs - compartments - subsystems

Limited access for detailed analysis

Test Rig (iGSL)

- Plexiglas box

- Gear interaction - Splashing - Losses

- Oil level & prop. - Shields / Baffles

P. Illg, A. Berg, D. Neufeld 8 ANSYS Conference & 33rd CADFEM Users' Meeting

June 24 – 26, 2015, Messe Bremen |

Background & Objectives Model Order Reduction: From Tractor to Component Test Rig

Tractor

Lots of different systems & circuits

Different focus & analysis goals

Gearbox

Lots of different - gear pairs - compartments - subsystems

Limited access for detailed analysis

Test Rig (iGSL)

- Plexiglas box

- Gear interaction - Splashing - Losses

- Oil level & prop. - Shields / Baffles

Animation

P. Illg, A. Berg, D. Neufeld 9 ANSYS Conference & 33rd CADFEM Users' Meeting

June 24 – 26, 2015, Messe Bremen |

Background & Objectives Gearbox CFD Challenges

–Gear interaction

• Full, No, Partially

– Numerical approaches

• E.g. MRF, sliding & dynamic meshes

–Multiphase & free surface flow

• Mesh & time step size

• Numerical modelling

– Calculation time & Scalability

Rotating walls (w/o teeth) Truncated gears Shrinked gears

Gear interaction – dynamic mesh

Air

Oil

P. Illg, A. Berg, D. Neufeld 10 ANSYS Conference & 33rd CADFEM Users' Meeting

June 24 – 26, 2015, Messe Bremen |

Background & Objectives Gearbox CFD Challenges

–Gear interaction

• Full, No, Partially

– Numerical approaches

• E.g. MRF, sliding & dynamic meshes

–Multiphase & free surface flow

• Mesh & time step size

• Numerical modelling

– Calculation time & Scalability

Rotating walls (w/o teeth) Truncated gears Shrinked gears

Gear interaction – dynamic mesh

Air

Oil

Animation

Air

Oil

P. Illg, A. Berg, D. Neufeld 11 ANSYS Conference & 33rd CADFEM Users' Meeting

June 24 – 26, 2015, Messe Bremen |

Content

John Deere – Today

Background & Objectives

Verification Procedure

Results

Conclusion

P. Illg, A. Berg, D. Neufeld 12 ANSYS Conference & 33rd CADFEM Users' Meeting

June 24 – 26, 2015, Messe Bremen |

Verification Procedure Identify Dominant Influence Factors

Brainstorming sessions, team effort: collect

physical & numerical factors

Influence Factors

Main Factors

Personal screening identify & select factors with highest impact on

splashing & losses

DoE

Numerical screening CFD meets DoE which factor has

dominant influence on which answer?

P. Illg, A. Berg, D. Neufeld 13 ANSYS Conference & 33rd CADFEM Users' Meeting

June 24 – 26, 2015, Messe Bremen |

Verification Procedure Solution Concept: Design of Experiments (DoE)

CFD Run

Rotation

Gear model

Temperature

Oil level

Rot. Speed

Mesh size

Time step

Met-hod

1 -1 -1 1 1 1 1 2 0 0 0 0 0 0 3 1 1 -1 -1 -1 -1 4 -1 -1 0 0 -1 -1 5 0 0 -1 -1 1 1 6 1 1 1 1 0 0 7 -1 0 -1 -1 0 -1 8 0 1 1 1 -1 1 9 1 -1 0 0 1 0 10 -1 1 0 0 0 1 11 0 -1 -1 -1 -1 0 12 1 0 1 1 1 -1 13 -1 0 1 1 -1 0 14 0 1 0 0 1 -1 15 1 -1 -1 -1 0 1 16 -1 1 -1 -1 1 0 17 0 -1 1 1 0 -1 18 1 0 0 0 -1 1

Most important 8 physical & numerical factors:

–DoE considering factor interaction: 864 CFD runs not feasible

levels

L/R disc trunc shrink

low mid high

low mid high

low mid high

coarse mid fine

coarse mid fine

fast stable accurate

P. Illg, A. Berg, D. Neufeld 14 ANSYS Conference & 33rd CADFEM Users' Meeting

June 24 – 26, 2015, Messe Bremen |

Verification Procedure Solution Concept: Design of Experiments (DoE)

CFD Run

Rotation

Gear model

Temperature

Oil level

Rot. Speed

Mesh size

Time step

Met-hod

1 -1 -1 1 1 1 1 2 0 0 0 0 0 0 3 1 1 -1 -1 -1 -1 4 -1 -1 0 0 -1 -1 5 0 0 -1 -1 1 1 6 1 1 1 1 0 0 7 -1 0 -1 -1 0 -1 8 0 1 1 1 -1 1 9 1 -1 0 0 1 0 10 -1 1 0 0 0 1 11 0 -1 -1 -1 -1 0 12 1 0 1 1 1 -1 13 -1 0 1 1 -1 0 14 0 1 0 0 1 -1 15 1 -1 -1 -1 0 1 16 -1 1 -1 -1 1 0 17 0 -1 1 1 0 -1 18 1 0 0 0 -1 1

Most important 8 physical & numerical factors:

–DoE considering factor interaction: 864 CFD runs not feasible

– Screening DoE: Taguchi L18 Design

• Full orthogonality

• 18 Runs

Responses: • Power losses

• Oil behavior

• Calculation time

P. Illg, A. Berg, D. Neufeld 15 ANSYS Conference & 33rd CADFEM Users' Meeting

June 24 – 26, 2015, Messe Bremen |

Verification Procedure Numerical Modelling with ANSYS Fluent

–Meshing gear interaction:

• Rotating sliding & dynamic mesh zones vs. static zones.

– Solver Settings:

• Multiphase flow: Volume of Fluid (VoF)

• Turbulent, incompressible, isothermal

• 3 mesh sizes: 1,4~11 Mio Tets

• 3 sets of solution methods: fast/accurate/stable

• 3 time step sizes: CFL 0,2~14

Truncated Gears – Sliding Mesh

Interacting Gears – Dynamic Mesh

Shrinked Gears – Sliding Mesh

Animation

P. Illg, A. Berg, D. Neufeld 16 ANSYS Conference & 33rd CADFEM Users' Meeting

June 24 – 26, 2015, Messe Bremen |

Content

John Deere – Today

Background & Objectives

Verification Procedure

Results

Conclusion

P. Illg, A. Berg, D. Neufeld 17 ANSYS Conference & 33rd CADFEM Users' Meeting

June 24 – 26, 2015, Messe Bremen |

0%

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Results #1: Losses Pareto Chart: Dominant Factors

– Rot. speed dominant.

– Top 5 factors:

• Physical & numerical “pairs”.

– Findings:

• Solution methods & gear representation more important than mesh size & time steps.

• Oil level & temperature more important than rot. direction.

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0 2 4 6 8 10 12 14

Lo

sses

Velocity [m/s]

P. Illg, A. Berg, D. Neufeld 18 ANSYS Conference & 33rd CADFEM Users' Meeting

June 24 – 26, 2015, Messe Bremen |

Results #1b: Losses Top3 Solution Methods & Oil Level

– Solution Methods:

• Accurate method calculates slower but moment converges faster

• Methods focusing on calc. speed & stability 50% lower losses

–Oil Level:

• Losses increasing with oil level

• Same influence level as num. settings

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1 3 5 7 9 11 13 15 17 19 21 23 25

Losses

Revolutions [-]

Shrinked Gears: 600/1200 rpm

Set1_stable

Set2_accurate

Set3_fast

Accurate methods:

more conservative loss prediction & overall faster converged solution.

To decrease losses decrease oil level.

Air

Oil

P. Illg, A. Berg, D. Neufeld 19 ANSYS Conference & 33rd CADFEM Users' Meeting

June 24 – 26, 2015, Messe Bremen |

Results #1c: Losses Top5 Gear Representation & Oil Temperature

–Gear representation:

• Significant influence on losses

• considering gear interaction: Losses x6 Faster moment stabilization

–Oil temperature:

• Toil density & viscosity losses

Truncated Gears

Interacting Gears

Volume fraction [-]

Air

Oil

Animation

P. Illg, A. Berg, D. Neufeld 20 ANSYS Conference & 33rd CADFEM Users' Meeting

June 24 – 26, 2015, Messe Bremen |

Results #2: Oil Pumping Effect Pareto Chart: Oil Volume above Initial

– Rotation speed dominant

– Solution methods:

• Fast method pumping effect

–Gear representation:

• Not significant for pumping effect

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Dominant factor

Not significant

Shrinked Gears: 600/1200rpm

Truncated Gears: 1500/3000rpm

Isosurface: 50% oil Vol.fraction, colored by velocity [m/s]

Animation

P. Illg, A. Berg, D. Neufeld 21 ANSYS Conference & 33rd CADFEM Users' Meeting

June 24 – 26, 2015, Messe Bremen |

Results #3: Oil Splashing Intensity Pareto Chart: Max Oil Height

–Oil level dominant

• Oil level reduction less oil splashing

– Rot. speed & mesh size Top3

– Rot. direction & solution methods

• Not significant

Low oil level

Mid oil level

High oil level

Isosurface: 50% oil vol.fraction, High speed: 1500/3000 rpm

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Dominant factor

Not significant

P. Illg, A. Berg, D. Neufeld 22 ANSYS Conference & 33rd CADFEM Users' Meeting

June 24 – 26, 2015, Messe Bremen |

Results #4: Calculation Time Pareto Chart: Calculation Time per Simulated Second

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Dominant factors

Less significant

–Gear representation & time step size dominant factors

• Dynamic mesh models need smallest time steps Calc. time 30x higher compared to truncated gears

• CFD cases w/o gear teeth accept biggest time steps Rotating discs fastest approach

DM: geom. limitation

meshes @2 timesteps

P. Illg, A. Berg, D. Neufeld 23 ANSYS Conference & 33rd CADFEM Users' Meeting

June 24 – 26, 2015, Messe Bremen |

Results #5: Calculation Time Pareto Chart: Calculation Time until Moment Stabilization

–DoE CFD runs: huge calc. time variation.

– Faster moment stabilization with more complex methods.

– Improvement of speedup & scalability desired!

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Dominant factors

P. Illg, A. Berg, D. Neufeld 24 ANSYS Conference & 33rd CADFEM Users' Meeting

June 24 – 26, 2015, Messe Bremen |

Content

John Deere – Today

Background & Objectives

Verification Procedure

Results

Conclusions & Outlook

P. Illg, A. Berg, D. Neufeld 25 ANSYS Conference & 33rd CADFEM Users' Meeting

June 24 – 26, 2015, Messe Bremen |

Conclusions

– Numerical models developed to use CFD in transient multiphase gearbox applications.

– Performed DoE to screen most important factors on oil splashing, losses & calculation time.

– Approaches with more physics and higher order solution methods are:

• More compute intensive, but show a faster moment stabilization.

• Show more realistic effects and are closer to literature results.

– Early design stages with simplified gears, detailed analysis needs more physics.

Volume fraction Air

Oil

Pressure

Animation

P. Illg, A. Berg, D. Neufeld 26 ANSYS Conference & 33rd CADFEM Users' Meeting

June 24 – 26, 2015, Messe Bremen |

Outlook

– Test rig investigations to receive known accuracy or deviation of stronger idealized models.

– Further investigations with numerical methods needed:

• Turbulence models & near wall treatment with boundary layers

• Surface tension models

– Speedup & Scalability improvements desired.

– Investigation of the interaction between the influencing factors.

– ANSYS Support extremely valuable in case of new methodology or any issues! Thank you!

Animation