Tripping

scale corrections for propellers using boundary layer tripping

Running

The aim of this JIP is to develop new propeller scale corrections to be able to predict full scale open water performance and propulsive performance more accurately.

Background

Full scale performance of propellers is still an area of large uncertainty during the propeller design phase, during the extrapolation of model tests for powering predictions and during full scale monitoring. On full scale, propellers usually operate with turbulent flow. On model scale, however, laminar flow, flow transition and more pronounced flow separation are encountered. Model tests and powering predictions suffer from these effects.

It is proposed to perform new open-water model tests using turbulators such that the boundary layer would be tripped towards a turbulent flow. Turbulators on the leading edge of the model scale propellers are very efficient in tripping the boundary layer. The turbulent flow on the propellers at model scale reduces the scale effect uncertainties. New scale corrections need to be applied, thereby replacing ITTC corrections that did not capture the scale effects correctly. The corresponding uncertainty of the final prediction and the standard deviation to full scale trials would greatly improve.

The Reynolds scale effects for a fully turbulent flow can be computed with CFD. MARIN is confident that using RANS computations, reliable scale corrections can be obtained for tripped propellers. These computations have become mature, reliable and robust, and are suited to this task.

Contact

Contact person photo

John Huisman

Senior Project Manager

OBJECTIVE
The Tripping JIP is aiming at reliable full-scale predictions for both open water performance and propulsive performance. The objective of this JIP is to develop new propeller scale-corrections to be able to predict more accurately full scale open water performance and propulsive performance.

SCOPE
The scope of the Tripping JIP project is defined in four work packages:
  1. Propeller open water model tests with turbulators – the F-series, FC-series, C-series and B-series will be revisited amongst other (public) propellers. About 100 model tests at 4 different Reynolds numbers are planned and 23 new propeller models will be manufactured.
  2. Open water RANS computations – study the performance at a large range of Reynolds number, up to full scale, with varying surface roughness. About 130 propellers will be extensively computed. A RANS workshop will be organized to set the CFD approach.
  3. Develop a generic scale correction method based on the model tests and RANS computations – to be used with tripped propellers to replace the currently used scale corrections. This will be at least a function of blade number, pitch, blade area ratio, J-value, Reynolds number (both at model scale and full scale) and full scale surface roughness. Correlation allowances for RANS computations will also be created based on this dataset.
  4. Develop a full scale B-series polynomial – combine the open water model tests, the RANS-computations and the generic scale correction method to make a new polynomial. A software package will be provided.

MOTIVATION
  • For propeller designers and manufacturers: less surprises during model tests or full scale trials and better control of the propeller design on both model scale and full scale.
  • For yards, ship owners and operators: more reliable full scale predictions and improved propeller designs.
  • For R&D: benchmark data for RANS computations on propellers for reference and quality checks.
  • For other research institutes, class societies and participants with their own model test facilities improvement of the extrapolation methodology and more reliable predictions.

PLANNING
The proposal has been discussed during the VOF meeting in Busan, South Korea, 30 November 2023. www.vesseloperatorforum.com. The minutes of meeting can be found below.
The next meeting has been in Venezia, Italy during The Blue Forum, in April 2024. According to the agenda below, 9 and 10 April were scheduled for further discussions.
On Tuesday 9 April, the meeting was open to all interested parties. On Wednesday 10 April, the meeting was open to committed participants only. During this meeting the priorities for the project were set and a decision was made on the project start date.

PARTICIPATION FEE
The cost of participation in the JIP is €15k per year for 3 years.
In view of of the number of participants, it was decided to extend the early bird participation fee until further notice.

SIGNED PARTICIPANTS AS OF YET
  • Kongsberg
  • ABB
  • Brunvoll Maritime Group
  • Damen Shipyards
  • COMMIT (Command Materiel and IT, Ministry of Defence)
  • MAN Energy Solutions
  • Kawasaki Heavy Industries, Ltd.
  • Samsung Heavy Industries Co., Ltd.
  • Steerprop Ltd.
  • Wartsila

For more information read the leaflet below or follow the Tripping JIP on LinkedIn.
PITCH - November 2023

Pitch

Recording (mp4)

Minutes

MARIN Strategy Better Ships Blue Oceans
literature