Task 2.1: Development and optimization of azimuth thruster for the reversible pump turbine
Work Package 2 spans over two years and includes four tasks, each managed by different project partners. We are responsible for Task 2.1, which aims to design and develop a rim-type azimuth thruster. The key objective is to create sufficient suction head (NPSH) to minimize cavitation for the reversible pump-turbine (RPT) in pumping mode operation. This work package corresponds to Phase 1 of the project, covering the first 24 months, with Task 2.1 being the largest task. This task closely collaborates with Task 2.2, led by Uppsala University, which focuses on designing and developing a rim-type electric motor for the thruster.
Overall timeline of the Task 2.1 in store2hydro project.
Progress
GENERAL ASSEMBLY
The project marked one year and the progress is presented at the General Assembly meeting TU Wien. Two milestones successfully achieved and discussed upcoming large scale measurements on reversible pump-turbine rig and thruster design.
General Assembly group picture. Image credit: Mark (WP7 Lead).
The test rig is being prepared for the phase 2 measurements of the reversible pump-turbine according to IEC standard. This measurements will also focus on cavitation characteristics. This data will provide valuable input for deciding the operational range of the thruster. The project teams aims to integrate additional pressure sensors in the draft tube for detailed data on pressure loading and cavitation. The turbine will also operated at extreme load conditions. The phase 2 measurements will focus on steady state operation of the turbine whereas transient and other measurements (phase 3) will be carried out soon after completing this measurements.
Hydraulic loop for the reversible pump-turbine in the Waterpower laboratory.
Second round of calibration for the critical instruments is initiated. Pressure sensors, flow meter, torque sensors will be calibrated prior to the phase 2 measurements. Johannes Djupesland along with Kerlef Valen Kerlefson lead the calibration campaign in the laboratory. Aim is keep random uncertainty below the prescribed limit in IEC60193 for these instruments.
We welcome new members in the project team. Gustav Oskar Ludvig Ambj̈ornsson will write master thesis during spring 2025. Ole Martin Fjuk will write project work during spring 2025 and master thesis during autumn 2025. Both students will work on design and optimization of the rim type thruster for the reversible pump-turbine.
MILESTONE 5
Initial validation of the numerical results have been carried out at selected steady state operating points of the reversible pump-turbine. The validation results looks good and provides confidence on selection of boundary conditions, computational domain, mesh and other physics. This completes the Milestone 5 (Experiments and numerical simulations of RPT are completed) in the project. Extensive verification and validation will be carried out during 2025 with phase 2 of the experiments and simulations.
Preliminary validation of the numerical results with the available experimental data.
Numerical modeling of the pump-turbine is initiated in August. Thee-dimensional geometry of the pump-turbine has been created by Mathias Eikebø. Later meshing was completed along with verification of the results to determine the discretization error. The simulation of the complete turbine was completed in November. The required boundary conditions for the simulations was considered from the experimental data from the phase 1 experiments.
Three-dimensional geometry of the reversible pump-turbine.
Experiments are conducted at steady state operating conditions and hill diagram is prepared. The overall efficiency is around 90% (nED = 0.225 and QED = 0.132), which is near to the expected values while comparing the standard model performance at the level of 2012. This provides confidence that the rig performs within the expected range. Around 150 operating points measured for the efficiency. The test rig is also operated at the pump mode operation to check performance. However, in order to perform optimally, the control system requires small adjustment that allows generator to make transition from turbine mode to the pump mode. This will also benefit to carry out the s-curve measurements.
Hill diagram of reversible pump-turbine at steady state operating conditions (Preliminary).
We welcome new members in the project team. Kerlef Valen Kerlefson and Mathias Eikebø will write the project and master thesis during 2024 - 2025 in this project. Kerlef Valen Kerlefson will work in the laboratory to carry out the experiments whereas Mathias Eikebø will carry out computational fluid dynamic simulations.
MILESTONE 4
Calibration of all major equipment is concluded. Overall uncertainty appears good, within ±0.2%. The major uncertainty is related to the flow measurement and torque measurement at extreme conditions. The second round of calibration will be performed during phase 2 measurements of the turbine efficiency. The test rig is ready for the phase 1 measurements. This marks the completing of Milestone 4.
Test rig for reversible pump-turbine is being prepared for the preliminary measurements and essential instruments are being integrated into the test rig. Flow meter, pressure transducers, torque sensors will be calibrated in coming days. Pump-turbine runner will be mounted (replacing the Francis-99 runner) into the existing rig. After integrating the runner, trial run of the rig will be initiated before summer vacation to verify the operating range and other parameters. The data will be checked available data and measurements (Characteristics of reversible-pump turbines, 2012).
Reversible pump-turbine runner in the Waterpower laboratory.
Johannes Djupesland joined the project team as a PhD candidate in the Waterpower laboratory. Johannes will work full time in this project for three years. We sincerely welcome Johannes in the project team and the Waterpower laboratory.
Detailed project plan is prepared and ready to start the activities.