Overview
Rijkswaterstaat (RWS) has set up a roadmap with the goal of developing new design guidelines for bottom protection near maritime infrastructure. In this context, the CROW working group was established to jointly develop research initiatives contributing to the knowledge gaps identified in the field of scour induced by propeller jets. The research program “SOP Schroefstraalbelasting onderzoeksprogramma” was developed under the TKI Delta Technology framework to gain a better understanding of the physical processes associated with scour induced by propeller jets, combining efforts from field measurements, scale models tests and numerical modelling.
In 2020 field measurements were performed in the Port of Ghent on jets induced by bow thrusters reflected on a vertical quay-wall, where flow velocities and pressures were measured along the quay-wall and near the bottom. Field measurements provide valuable insight into the flow phenomena in prototype scale. However, due to limitations in the field, assessing the influence of all relevant parameters is practically not feasible. Therefore, using the field measurements as basis, scale model tests and numerical simulations are being performed to extend the existing database by a systematic variation of parameters. The numerical simulations will be developed by MARIN and the scale model tests will be performed by Deltares.
The field measurements performed in the Port of Ghent in 2020 are used as basis (i.e. prototype) for the physical scale model research. The prototype dimensions have been scaled down to an appropriate scale and a systematic variation of the key parameters were performed, aiming at characterizing the three-dimensional flow field originated by a jet reflected on a vertical wall resulting from a bow thruster. The main goal of the scale model tests is to improve the general understanding of the flow behavior, and to create a benchmark dataset for validation of CFD models.
Promotional video
Timeline
The scale model tests have started in 2021. Postprocessing and data analysis will be performed in 2022. The project is expected to end by September 2022.
Measurements
Particle Image Velocimetry (PIV) is used to visualize and characterize the turbulent jet created by a bow thruster. The following parameters were varied between tests:
- under-keel clearance
- quay-wall clearance
- rotational speed of the propeller (jet flow velocity)
- PIV measurement plane
Results
Preliminary results from the scale model tests can be found in the links below:
- Ux time averaged
- Uz time averaged
- Ux standard deviation
- Uz standard deviation
- EMS ux and uy
- Ux max near bed
- RPM_UBT2_WL
