NORBERT BULTEN WARTSILA PROPULSION THE...

Doc.ID: Revision: Status: 15 / © Wärtsilä

FROM 40 HOURS TO 15 MINUTES, 15 YEARS OF EXPERIENCE WITH

CFD NORBERT BULTEN

WARTSILA PROPULSION THE NETHERLANDS

23 March 2011 1 CD-adapco User conference / Norbert Bulten


Topics

•  Introduction Wärtsilä Propulsion

–  Products

–  History of CFD within Wärtsilä

•  First wave: Implementation of CFD method

–  Get the CFD tool at similar level as existing research methods

–  Main focus: validation

•  Second wave: Utilizing CFD method stand-alone –  Use CFD to understand the physical phenomena

–  Main focus: interpretation

•  Summary and outlook



Introduction Wärtsilä Propulsion

•  Wärtsilä is one of the key suppliers in the world of marine Diesel engines and propulsion systems.

•  Within Wärtsilä Propulsion a wide range of propulsion products is being developed, manufactured and maintained. Examples are:

–  Controllable and Fixed Pitch propellers –  Azimuthing thrusters

–  Tunnel thrusters

–  Waterjets



Introduction Wärtsilä Propulsion

•  Propulsion products on wide range of vessels



Introduction: history of CFD

•  From Star-CD version 2.1 in 1996 to Star-CCM+ 6.02 in 2011

•  Scope of applications has grown extremely

•  Target is Full-scale numerical towing tank


1996: Star-CD at Lips -waterjet department

2000: CFD propeller analysis

2005: CFD thruster analysis

2008: Propeller-hull interaction

2011: virtual towing tank


Introduction: history of CFD

•  1999 – Star – user conference presentation on automated meshing tool for waterjet inlets


•  2002 – Star – user conference presentation on applications of waterjet inlet design tool.

•  Calculation time 40 hours

•  2011 – calculation time 15 minutes


First wave: Implementation of CFD

•  Key factors for successful implementation

–  Quick pre-processing •  Robust geometry handling

•  Automated meshing process

•  Standardized boundary conditions

–  Commercially acceptable calculation times –  Well-defined qualitative post-processing

•  Standardized output format of results

–  Method validated with aid of experimental results



First wave: Implementation of CFD •  Second application: propellers

•  Automated meshing tool for open and ducted propellers

•  Validation carried out for numerous propellers

•  Streamlined processes to ensure Quality Assurance



The results of implementation in daily work

•  Automated process should give user-independent results and should be easy in use



Second wave: Utilization of CFD

•  Creation of large data set

–  Geometry variation

–  Complete range of operating conditions

•  Understanding physical phenomena

–  Utilizing post-processing options •  Qualitative review: contour and vector plots

•  Quantitative review: integrals and force summation

•  Scaling effects on ducted propellers –  Validation of results

–  Development of alternative post-processing methodology

–  Testing of concept

–  Interpretation of results on model scale and full scale



Performance prediction of ducted propellers

•  In marine industry a debate is ongoing about the existence of Reynolds scaling effects on the performance of ducted propellers.


Comparison CFD with model scale experiments → Good match

Comparison CFD model scale and full scale → Clear difference

How to explain these results?


Alternative post-processing

•  New post-processing methodology is based on viscous losses and axial pump efficiency


ein

vin

pin

v1

p1

v2

p2

vout

pout

eout,all hpump=hrotor+Dhrotation

vp


Verification of concept

•  Ducted propeller performance is split into different components:

–  Open water performance

–  Pump efficiency

–  (Viscous) inlet loss –  Exit loss

–  Rotational loss

•  Total efficiency adds up to 100%



Comparison of results on model and full scale

•  Ducted propeller performance for different nozzles (HR & 19A)

–  Pump efficiency

–  (Viscous) losses


•  Clear trends found in pump efficiency and viscous losses.

•  Results are in line with expectations and literature

•  Physical explanation of scaling phenomenon has been revealed.


Summary

•  First wave: from Colors For Directors to CFD –  Get the CFD tool at similar level as existing

research methods

–  Main focus: validation

•  Second wave: from CFD to Confident Foundation for Design

–  Use CFD to understand the physical phenomena

–  Main focus: interpretation



Outlook

•  Third wave: towards Computer-driven F(v)ariations in Design

–  Design based on optimization methods

–  Main focus: product performance

•  And this might bring the calculation time back to 40 hours……



Questions?


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