Propeller Cavitation RINA Presentation 7 October 2015

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Cavitation and Erosion on Marine Propellers

Prepared by Dr Dmitriy Ponkratov,Senior Consultant, Fluid Dynamics Group, Technical Investigation Department07 October 2015



Lloyd’s Register Ship Performance Group (SPG)

ShipPerformance

Group

Fuelmanagement

team

Maintenancemanagement

team

CFD andhydro

optimisationteam

Measurementand

observationsteam

Navalarchitecture

and

engineeringteam

Fuels, lubes, emissionsand new technologies

Asset managementcondition

monitoring/maintestrategies

Technical andoperationaldesign/retrofit efficiency

Full-scale trials andmeasurement systemsdeployment

Propulsion and systemsoptimisation / logistics

planning and modelling

SPG: Meeting the challenges of

energy efficiency andenvironmental regulatorycompliance



Technical Investigation Department, 7 October 2015

Model scale tests witnessing

• Resistance tests

• Propulsion tests

• Cavitation tests

• Erosion tests

• Paint tests

• Air bleeding tests

• Pressure pulses measurements




Cavitation tests at cavitation tunnels

First cavitation tunnel was built byin Newcastle in 1895




Cavitation tests




Cavitation tests at depressurised towing tank




Erosion tests at cavitation tunnel




Erosion tests at cavitation tunnel




Full scale measurements

• Cavitation observations

• Erosion inspections

• Sea trials measurements

• Pressure pulses measurements




Cavitation observations




Borescope Installation




Cavitation observations




Erosion inspections




Erosion due to Tip Vortex Cavitation




Erosion Inspection: Tip Vortex Damage from a Pre-Swirl Fin




Erosion Inspection: Monitoring Diver Inspections




Acoustic emission (AE) measurements




Acoustic emission measurements: Synchronised AE & Video




Thrust and Torque measurements




Rudder angle records




Shaft speed records




Computational Fluid Dynamic projects

• Hull form optimisation• Trim optimisation

• Cavitation modelling

• Erosion predictions

• Resistance predictions

• Performance predictions

• Other projects




Cavitation Erosion Prediction Semi cylinder




Cavitation-Erosion Prediction – Triangular Prism

Experiment

Maximum Impact Pressure

hear layer cavitation

Tip vortex

Maximum Erosive Potential

Maximum Impact Pressure




Case study 1 – Model scale hydrofoil NACA0015

• Computational domain identical to a

section of cavitation tunnel;• Conditions identical to cavitation tunnel

set up;

• Symmetry plane in the middle;

• Initial runs by RANS (K-Omega model);

• Final runs by DES;

• Trimmer mesh;

• 4 mill cells;

• Time step 1.0x10-6 sec









High Speed video frames from model test

CFD cavitation prediction

Solution time0.084415 s




Soluti0.08




High Speed video frames from model test

CFD cavitation prediction





Soluti0.08






Flow

Modeltest paintremoval

Erosivefunction

N1

Erosivefunction

N5

Erosivefunction

N8

Flow

Flow

Flow




Case study 2 – Ship scale containership’s rudder in wake

•

Simulation conditions identical to shipsea trials;

• Initial runs by RANS (K-Omega model);

• Final runs by DES;

• Trimmer/ Polyhedral mesh

• 16 mill cells (11.5 mill in rotation part);

• Time step 0.001 sec





Stage 1.

Whole domain simulation with free surfacebut without cavitation.

Stage 2.

Aft part of the domain simulation withcavitation.

Symmetry condition on the wavy freesurface.





C d 2 Shi l i hi ’ dd i k




• After the activation of cavitationmodel the hub vortex was observed;

• The tip vortex propagation was notresolved completely due to thecoarse mesh downstream ofpropeller blades.


C t d 2 Shi l t i hi ’ dd i k




Propeller

Rudder

Rudder


Paint damage area

Erosive Function№5 Erosive Function

Erosive Function

C t d 3 Shi l ll i k




Case study 3 – Ship scale propeller in wake

Cavitation growth in the wake peak

C i i E i P di i




Cavitation-Erosion Prediction



Lloyd’s Register and variants of it are trading names of Lloyd’s Register Group Limited, its subsidiaries and affiliates. Copyright © Lloyd’s Register EMEA. 2015. A member of the Lloyd’s Register group.

Dr Dmitriy PonkratovSenior ConsultantTechnical Investigation DepartmentE [email protected]

Lloyd’s Register EMEA

Global Technology Centre, Southampton Boldrewood InnovationCampus, Building 175, Burgess Road, Southampton, SO16 7QF

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mailto:[email protected]

mailto:[email protected]

Documents

Propeller Cavitation RINA Presentation 7 October 2015