Smart Rivers 2011 PIANC New Orleans, LA USA. Overview114-ft TowboatNumerical Towing...

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THE APPLICATION OF COMPUTATIONAL FLUID DYNAMICS (CFD) TO RIVER TOWBOAT DESIGN

Smart Rivers 2011PIANCNew Orleans, LAUSA

Overview 114-ft Towboat Numerical Towing Tank Propeller Rudder AOA Closure

• Authors:

Brant R. Savander, Ph.D., P.E.Principal Research ScientistMaritime Research Associates, LLCAnn Arbor, MIUSA

Gregory LeeNaval ArchitectMarine Design CenterUS Army Corps of EngineersPhiladelphia, PAUSA

• Acknowledgements:

Sergio FifiNaval ArchitectJensen Maritime Consultants, Inc.

Johan SperlingNaval ArchitectJensen Maritime Consultants, Inc.

OVERVIEWThe Application of CFD to River Towboat Design

• USACE Towboat Example: EVANICK

• Towboat Design Attributes & Challenges

1. Hull form incorporates propeller tunnels.

2. Steering and flanking rudders ahead and

aft of propeller.

3. Thrust and steering equally important in

ahead and astern operation.

4. Propeller diameter limited and heavily

loaded.

5. Large Variation in barge tow size gives

large range of propeller operating points.

• USACE: 114-ft, 1500-hp per shaft

• Steering & Flanking Rudders• Strut• Propeller Diameter & Tip Clearance

• Wake Adapted Blade Shape• Wake Aligned Appendages• Comparison to Z-Drives

USACE 114-FT TOWBOAT APPLICATION

The Application of CFD to River Towboat Design

• Design & Analysis Objectives:

1. Wake alignment of struts and rudders.

2. Wake adapted propeller design.

3. Propeller diameter trade-off analysis:

efficiency vs. pressure pulse levels.

4. Match propeller and hull to a “wide

operating speed range” rated engine.

5. Evaluate maximum forces on steering and

flanking rudders at hard over angles.

• Outboard Profile

• LOA: 114’-0’’• BOA: 35’-0’’• Depth: 10’-3’’ (molded)• Max. Air Draft: 60’-6’’

• General Arrangement

NUMERICAL TOWING TANK – FULL SCALE

• Computational Geometry

• Computational Domain: Full Scale Tank

Lateral Symmetry

Bottom Boundary

Velocity Inlet

Pressure Outlet

• Computational Domain: Full Scale Tank

Lateral Symmetry

Bottom Boundary

Velocity Inlet

Free Surface

• Rudder and Propeller Mesh

• Results: Full Resolution of Pressure Field

• Results: Full Resolution of Velocity Field

• Stock Appendages: Axial Velocity

• Wake Adapted App.: Axial Velocity

USACE TOWBOAT PROPELLER

• Propeller Drawing

• Propeller Distributions

RUDDER ANGLE VARIATION

• Example: Steering Rudders – 20 deg.

• Free Surface: Steering 20-deg

• Streamlines: Steering 20-deg

• Steering Angle Force Summary

• Flanking Rudder Angle Force Summary

RESULTS & CONCLUSIONSThe Application of CFD to River Towboat Design

• Results: Struts & Rudders

1. Inboard Flanking Rudder: LE outboard 3.3

2. Outboard Flanking Rudder: LE outboard

7.2 deg.

3. Inboard Steering Rudder: LE inboard 2.3

4. Outboard Steering Rudder: LE outboard

5.9 deg.

5. Maximum Rudder Side Force: 40-45 deg.

6. Struts – Wake Aligned at ahead speed of

8.7 kts.

• Results: Propeller

1. Compared w/ flat face geometry

a. 35 % reduction in unsteady shaft thrust and torque amplitude.

b. 25 % reduction in radiated pressure pulse levels.

c. 3 % increase in openwater efficiency.

d. Tip clearance reduced from 15% D to 10% D.

e. Propeller diameter increase from 79’’ to 82.5’’

2. Full 3D CNC propeller models. ABS Class.

• Closure

Thank You .

Smart Rivers 2011 PIANC New Orleans, LA USA. Overview114-ft TowboatNumerical Towing...

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