1. Analysis of numerical self-propulsion simulations with a Pre-Swirl Stator
Koen In de Braekt
Wärtsilä, Propulsion System Services
Drunen, Netherlands
Analysis of Numerical Self-Propulsion Simulations with a Pre-Swirl Stator / Koen In de Braekt

2. Propulsion Services are offered for Wärtsilä & Non Wärtsilä products
Propulsion System Services
Upgrades & retrofits
Maintenance overhauls & repairs
Propulsion controls
Propulsion monitoring & analysing
Environmental legislation
Propulsion Services are offered for Wärtsilä & Non Wärtsilä products
Propellers (CPP & FPP)
Marine Gearboxes
Thrusters (STT & TT)
Waterjets
Controls
The Propulsion System’s reliability directly affects the safe navigation and overall efficiency of the ship.
Our role is to serve Marine & Offshore Industry customers throughout the lifecycle of their installations, from the first discussions during the design phase of a vessel to the end of its operational life. This means taking full responsibility, rather than just supplying parts promptly or sending a maintenance specialist to fix a problem. In line with the ongoing industry changes, we have introduced new products to the market to improve the efficiency, reliability, and safety of those vessels already in service
Analysis of Numerical Self-Propulsion Simulations with a Pre-Swirl Stator / Koen In de Braekt

3. Propulsion Products for All Segments
Analysis of Numerical Self-Propulsion Simulations with a Pre-Swirl Stator / Koen In de Braekt

4. ESDs can be split into Upstream and Downstream features
Energy Saving device (ESD)
These ESDs are passive parts, which contribute to increased overall efficiency
ESDs can be split into Upstream and Downstream features
Pre-study during GRIP (Green Retrofit through Improved Propulsion)
Pre-Swirl Stator (PSS) most promising
Analysis of Numerical Self-Propulsion Simulations with a Pre-Swirl Stator / Koen In de Braekt

5. Setup method to evaluate the performance of a Pre-Swirl Stator
goal
Setup method to evaluate the performance of a Pre-Swirl Stator
Determine power reduction of a Pre-Swirl Stator with numerical Self-Propulsion
Power reduction is less fuel consumption
Analysis of Numerical Self-Propulsion Simulations with a Pre-Swirl Stator / Koen In de Braekt

6. The nominal wakefield for a single screw propeller hull is non-uniform
working PRINCIPLE PRE-SWIRL STATOR
The nominal wakefield for a single screw propeller hull is non-uniform
Analysis of Numerical Self-Propulsion Simulations with a Pre-Swirl Stator / Koen In de Braekt

7. Variable pitch, rake, camber, chord length, etc.
Pre-swirl stator design
Variable pitch, rake, camber, chord length, etc.
Flow modified at lower radii
Unloading at tip to prevent tip vortices
Analysis of Numerical Self-Propulsion Simulations with a Pre-Swirl Stator / Koen In de Braekt

8. Standard k-ε turbulence model Free surface VOF approach
Physics and mesh settings
STAR-CCM+ v9.04
Standard k-ε turbulence model
Free surface VOF approach
Second order in space and time
Unstructured trimmed mesh
Moving Mesh
Fixed sinkage and trim
Approx. 10M cells
Analysis of Numerical Self-Propulsion Simulations with a Pre-Swirl Stator / Koen In de Braekt

9. Bare hull resistance
Analysis of Numerical Self-Propulsion Simulations with a Pre-Swirl Stator / Koen In de Braekt

10. Wakefield extracted from bare hull resistance calculationsno
PSS
PSS
Wakefield extracted from bare hull resistance calculations
Circumferentially averaged tangential velocities
Analysis of Numerical Self-Propulsion Simulations with a Pre-Swirl Stator / Koen In de Braekt

11. The more the inflow is adjusted, the more resistance is created
Bare hull RESISTANCE Calculations
The more the inflow is adjusted, the more resistance is created
Analysis of Numerical Self-Propulsion Simulations with a Pre-Swirl Stator / Koen In de Braekt

12. Self-propulsion
Analysis of Numerical Self-Propulsion Simulations with a Pre-Swirl Stator / Koen In de Braekt

13. Propeller efficiency increases due to improved inflow
180 deg
0 deg
Propeller efficiency increases due to improved inflow
Analysis of Numerical Self-Propulsion Simulations with a Pre-Swirl Stator / Koen In de Braekt

14. Pre-Swirl Stator increases rudder resistance
Rudder interaction
No Pre-Swirl
Stator
Pre-Swirl
Stator
Rudder Resistance
No PSS
6.1%
PSS
7.3%
Pre-Swirl Stator increases rudder resistance
Analysis of Numerical Self-Propulsion Simulations with a Pre-Swirl Stator / Koen In de Braekt

15. Good agreement in RPM reduction
Power reDUCTION
Good agreement in RPM reduction
Power reduction trends are captured, level of reduction requires improvement
Analysis of Numerical Self-Propulsion Simulations with a Pre-Swirl Stator / Koen In de Braekt

16. Resistance calculations give good first indication
conclusions
Resistance calculations give good first indication
Effects of pre-swirl stators in wakefield clearly visible
Trends in fin resistance are captured
Increase of propeller efficiency in behind in self-propulsion well captured
Interaction effects very important
Take the entire system into account for proper conclusions
Level of power reductions requires further improvement
Analysis of Numerical Self-Propulsion Simulations with a Pre-Swirl Stator / Koen In de Braekt

17. Sensitivity study on turbulence models
Future work
Sensitivity study on turbulence models
Model test measurements for validation
Investigate possibility of design of experiments
Analysis of Numerical Self-Propulsion Simulations with a Pre-Swirl Stator / Koen In de Braekt

18. Thank YOU Koen In de Braekt koen.indebraekt@wartsila.com
Wärtsilä Propulsion Services
Drunen, The Netherlands
Analysis of Numerical Self-Propulsion Simulations with a Pre-Swirl Stator / Koen In de Braekt