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WERK SALZGITTER

OpenFOAM in component development

Case studies from a productive CFD environment

Volkswagen AG – HS-2 – Dr. Andreas Gitt-Gehrke – Stand: 05.11.2008 – 2WERK SALZGITTER

Agenda

1 Presentation of Volkswagen Salzgitter

2 CFD in engine component development

3 Reasons for using OpenFOAM

4 Case studies

5 Future plans

6 Concluding remarks


Volkswagen - Business Unit Salzgitter



Diesel engines

2,5 l 5-cylinder

128 kW 400Nm

5,0 l 10-cylinder

230 kW 750 Nm2,0 l 4-cylinder

125 kW 350Nm

1,4 l 3-cylinder

59 kW 195 Nm

6,0l 12-cylinder

309 kW 560 Nm

Automotives

8,0l 16-cylinder

736 kW 1250 Nm

Gasoline engines

3,6 l 6-cylinder

206 kW 360 Nm

1,4l 4-cylinder

59kW 132 Nm

Engines



1,9 l 4-cylinder

44 kW 125 Nm

2,5 l 5-cylinder

121 kW 310 Nm

3,0 l 6-cylinder

165 kW 450 Nm

Marine enginesApplication

Industrial engines

3,2 l 6-cylinder

183 kW 320Nm

1,0 l 4-cylinder

59 kW 86 Nm

1,9 l PD 4-cylinder

74 kW 285 Nm1,9 l 4-cylinder

63 kW 215 Nm

Special engines



Development of componentsProprietary Switching intake tubeDevelopment : Roller cam follower

Oil pumpsVacuum pumpsRails for CR-engines

Optimization of product costs

Spur gear

Oil pan

Bucket tappet

Oil pumpPump-injector drive

Fly wheel Roller cam follower

Rotatory parts

Piston pin

Cubic parts Pumps + otherValve train

Intake tube

Power-train mount

Balance shaft Pump

Bearing Frame

Engine components


CFD in component development

All sorts of guided flow systems

• Oilpumps

− External gear pumps

− Gerotor pumps

− Control pistons

• Vacuum pumps

• Intake tubes / charge air systems

• Other flows …


CFD in component development

CFD

Design details

Problems occuring inprototypes and

production

Design optimization


Reasons for using OpenFOAM

OpenFOAM is

• easy to use (from a UNIX perspective)

• variable and extendable

• adjustable to individual problems

• cost efficient.

As pre- and post-processors ANSA and

Ensight are used.


Case studies

The case studies on three different components presented here

• involve only „simple“ CFD

• are directly validated via prototypes and experiments.

The engineers rely on the CFD results.

CFD is highly appreciated within the design process.


Case study (I)

For quality assurance the final common rail assembly is analyzed with

respect to dirt particles via random sampling.

The aim was to optimize the rinsing procedure used for the analysis.


Case study (I)

From RANS calculations the best setup for the analytic rinsing procedure

could be computed.

Estimates for minimal rinsing time and suggestions for further

improvements could be made.


Case study (I)


could be computed.




Case study (II)

The control piston of an oil pump

was adjusted to fit dynamic pressure

effects.

The original design

showed some

hysteresis effect.


Case study (II)

Calculation:

• Model including gaps

• Various positions of the piston

• The same inlet flow rate for all positions

• Outlet pressure from measurements

Results:

• Stable pressure – spring force balance

• At least one more metastable balance

position (bifurcation problem)


Case study (II)

To avoid the transition to the metastable

trajectory the dynamic behaviour of the

control piston needed to be changed.

Introduction of a small concentric groove

reduced the side forces by a factor of

three without showing leakage effects.

The changes were successfully

implemented.


Case study (III)

Design optimization on vacuum pump

inlet and outlet flows.

• Start with maximum design space

• Apply a „0th order“ adjoint topology

optimization (Dr. Othmer, Volkswagen

Research Department)

• Iterate between topology optimization

and design restrictions

• Final model with minimal pressure

loss

Inlet

Outlet

Simplified model of rotary vacuum pump


Case study (III)

Maximum design space for the inlet.

Three variants attaching the pump

chamber

• at the side and at the bottom

• at the side only

• at the bottom only.


Maximum design space for the

inlet.


chamber




Case study (III)


Design iterations and final result.

Minimal pressure loss

Case study (III)


Design optimization of vacuum pump outlet region.

Case study (III)


Compressible calculation of the evacuation to estimate pressure loss in

the valve.

Case study (III)

2/3 of the pressure loss

take place in the valve.


Lessons learned:

• Experiments showed only small differences in evacuation efficiency

with and without valve.

• Calculations confirmed that showing strong recirculation areas.

Simulation results

Valve

No valve

Case study (III)


Future plans

This is what we plan for 2009 ...


Future plans

This is what we plan for 2009 …

… and 2010 we would like to be

able to do it in OpenFOAM!!!


Concluding Remarks

• Despite the growing number of hexaedral meshers there is still the

need for purely polyhedral mesh generators to suit complex

geometries better.

• A more generalized scheme for dynamic mesh movement would be

great, probably based on (pre-)defined trajectories of the boundaries.


Concluding Remarks

OpenFOAM is a good choice for daily productive work if …

• you have a decent pre- and postprocessing tool and

• you don‘t mind doing the job without a GUI.

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