Qulaity Review AC6-04
Application Challenge 6-04 © copyright ERCOFTAC 2004
The application challenge Pump Turbine is a highly relevant and extremely ambitious and challenging test case for validation of CFD for incompressible turbomachinery flows within QNET-CFD.
The data for the test case arises from the project HPNURSA (High Performance Numerical Rotor Stator Analysis), see http://lmhwww.epfl.ch/HPNURSA/. This is a European Consortium project funded by the European Community ESPRIT Program which was successfully launched in 1998. AEA Technology GmbH is one of the major software partners in the consortium, working closely with Hydro Vevey (now part of VATECH Hydro) and Voest Alpine as industrial end-users and the University of Lausanne (EPFL) and the University of Lyon (ECL) as academic partners. In view of the fact that the test case involves a complete turbomachine it will be particularly useful as a basis for assessing strategies for computing the whole machine using a range of models for the interface between rotating and stationary components ranging from frozen rotor, mixing planes, to a fully unsteady simulation. The geometry is complex in that it involves a complete turbomachine (inlet, impeller, stator vanes and outlet casing), and the flow is complex in that it involves both design point operation and off-design operation with flow separation and instabilities.
In the QNET-CFD test case only the design point flow is considered and the unsteady effects are neglected, but the case is still relatively complex as the machine under consideration is a pump-turbine operating in pump mode with strong adverse pressure gradients.
The project is still running and the full documentation of the measurement data is not yet available. This review has been completed on the assumption that the data will be fully available and documented in the quality needed will be available at the end of the HPNURSA project.
The checklist below identifies that this test case is a good test case for an application challenge within QNET-CFD. The important comments in this checklist are summarised here:
· Experiments: The project is still running and the full documentation of the measurement data and accuracy are not yet available.
· Simulations: The major uncertainty in the simulations is that a number of simplifications to the geometry have had to be made. The computational domain has been limited to the runner and the guide vane blades with a rotationally symmetric inlet cone and outlet diffuser instead of the draft tube and volute. The number of stator vanes has been reduced by 10% to allow a periodic calculation with one rotor and four stator vanes.