Azipod ® propulsor in oblique flow at full scale: STAR Global Conference 2017 Berlin, march 2017 Azipod ® propulsor in oblique flow at full scale: comparison between traditional approach and fully coupled FSI for propeller stress analysis Dr Pasi Miettinen, Senior CFD Analyst, ABB Marine, Helsinki, Finland

Agenda Earlier presentations and background Azipod ® propulsor in oblique flow at full scale propeller stress analysis Comparison between simulation approaches Conclusions November 21, 2018

Earlier presentations and background Dr Pasi Miettinen and Andrei Korsström, Full scale CFD simulation of Azipod unit performance at varied steering angles, STAR Global Conference 2014, Vienna, March 2014 Dr Pasi Miettinen, Use of STAR-CCM+ for Marine applications at ABB Marine, Oil, Gas and Chemical CFD Conference 2014, Houston, November 2014 Dr Pasi Miettinen, Use of STAR-CCM+ for Propeller simulations at ABB Marine, CD-adapco Marine Workshop, Helsinki, January 2016 Statements in 2014 November 21, 2018

Azipod ® propulsor in oblique flow at full scale Propeller stress analysis Method 1 Method 2 Method 3 Transient CFD analysis Static FEM analysis Third party software Import data, map imported data on FE mesh and check mapping quality (visual, thrust and torque) Run analysis Need for rerun? Transient CFD analysis Static FEM analysis STAR-CCM+ 11.02.009 Import data, map imported data on FE mesh and check mapping quality (visual, thrust and torque) Run analysis Need for rerun? Fully coupled transient Fluid Structure (FSI) analysis No need for data transfer Only one sim file CFD and FE meshes and solvers One-way coupling (CFD -> FEA) Two-way coupling (CFD <-> FEA) Export pressure and wall shear stresses on propeller surfaces based on thrust or torque Export pressure and wall shear stresses on propeller surfaces based on thrust or torque November 21, 2018

Azipod ® propulsor in oblique flow at full scale Propeller stress analysis Method 1 Transient CFD analysis Static FEM analysis Third party software Import data, map imported data on FE mesh and check mapping quality (visual, thrust and torque) Run analysis Need for rerun? Export pressure and wall shear stresses on propeller surfaces based on thrust variation Static pressure on CFD mesh Mapped pressure on FE mesh Propeller thrust is equal on both meshes Minimum principal stress Amplitude and mean at 0.6 R are used in a semi empirical formula for estimating propeller fatigue strength by high cycle stress criterion November 21, 2018

Azipod ® propulsor in oblique flow at full scale Propeller stress analysis Method 1 Method 2 Method 3 Transient CFD analysis Static FEM analysis Third party software Import data, map imported data on FE mesh and check mapping quality (visual, thrust and torque) Run analysis Need for rerun? Transient CFD analysis Static FEM analysis STAR-CCM+ 11.02.009 Import data, map imported data on FE mesh and check mapping quality (visual, thrust and torque) Run analysis Need for rerun? Fully coupled transient Fluid Structure (FSI) analysis No need for data transfer Only one sim file CFD and FE meshes and solvers One-way coupling (CFD -> FEA) Two-way coupling (CFD <-> FEA) Export pressure and wall shear stresses on propeller surfaces based on thrust or torque Export pressure and wall shear stresses on propeller surfaces based on thrust or torque November 21, 2018

Azipod ® propulsor in oblique flow at full scale Propeller stress analysis Method 3 Fully coupled transient Fluid Structure (FSI) analysis No need for data transfer Only one sim file CFD and FE meshes and solvers One-way coupling (CFD -> FEA) Two-way coupling (CFD <-> FEA) November 21, 2018

Azipod ® propulsor in oblique flow at full scale Propeller stress analysis Red line Method 3 Fully coupled transient Fluid Structure (FSI) analysis No need for data transfer Only one sim file CFD and FE meshes and solvers One-way coupling (CFD -> FEA) Two-way coupling (CFD <-> FEA) Blue line Green line November 21, 2018

Azipod ® propulsor in oblique flow at full scale Propeller stress analysis Method 1 Method 3 Transient CFD analysis Static FEM analysis Third party software Import data, map imported data on FE mesh and check mapping quality (visual, thrust and torque) Run analysis Need for rerun? Fully coupled transient Fluid Structure (FSI) analysis No need for data transfer Only one sim file CFD and FE meshes and solvers One-way coupling (CFD -> FEA) Two-way coupling (CFD <-> FEA) Export pressure and wall shear stresses on propeller surfaces based on thrust or torque November 21, 2018

Comparison between simulation approaches Propeller stress analysis Method 3 (Fully coupled transient Fluid Structure analysis) Method 1 (Transient CFD + external FEA) Pros Very clear work flow First CFD and then FEA Analysis are decoupled CFD expert for CFD work FEA expert for FEA work Cons Possibly large amount of data from CFD Exported CFD data correct for FEA? Data collection frequency Might miss extreme values Data transfer and mapping Pros Full control of both analysis No data transfer, only one sim file Need expert who knows both CFD and FEA This approach works very well even for the very first time Cons If you want modify something Mesh settings or run CFD first then you need to update reports etc… Room for improvement if all the settings are not correct first time or you want to add some features during simulation steps November 21, 2018

Conclusions High Performance Computing (HPC) combined with automated meshing operations and java macros has accelerated the design cycle significantly Parts-based meshing is one of the best improvements I have seen within STAR-CCM+ Next year inclusion of the stress solver with FEA approach will further speed up the the design cycle In 2015 the inclusion of the stress solver with FEA approach has further sped up the the design cycle Now only 3D solid elements, waiting for shell elements November 21, 2018