Test case

NUMERICAL STUDY

Numerical study was performed on same model turbine. The complete geometry of the turbine was be provided. The geometries were prepared in different formats. However, the preliminary was performed using ANSYS CFX v14. The geometry and mesh were prepared using ICEM CFD v14. Therefore, ICEM CFD mesh at these three operating points was also be provided. One can directly use this mesh and perform numerical studies by setting up own flow physics. The provided experimental data were used for the necessary boundary conditions and comparison of the numerical results. The geometries include wetted surfaces only. The geometry files also includes block (*.blk) file and the block file should be used to create mesh in ICEM CFD. The explanation about creating mesh from the block is given in ANSYS help manual. First you may need to create pre-mesh then convert to unstructed by right clicking on pre-mesh, and export the mesh for the simulation.

Figure 3 Computational domain of the model Francis turbine. Inlet face is identical to the pressure measurement location. The turbine includes three domain, spiral casing with distributor, runner, and draft tube. The domain can be connected using appropriate interface. Runner is a rotating domain. The rotation direction, clockwise/anti-clockwise, must be checked with reference to the guide vane position.

Figure 4 Spiral casing and distributor of Francis-99 turbine.

 ICEM CFD Geometry and pre-mesh at PL

 ICEM CFD Geometry and pre-mesh at BEP

 ICEM CFD Geometry and pre-mesh at HL

Three dimensional geometry of the runner is prepared using ANSYS ICEM CFD software. It is prepared in two parts: (1) complete runner and (2) small area below the runner cone. There was difficulty in creating ICEM CFD blocks below the runner cone therefore it is divided in two parts. However, one can select part-1, you choose to create own mesh.

Figure 5 Francis-99 runner.

 Francis-99 runner geometry and pre-mesh

Figure 6 Computational domain of the model Francis turbine draft tube.

 Francis-99 draft tube geometry and pre-mesh

The locations of pressure sensors and velocity measurements can be used to create monitoring points during the simulation for comparison with the experimental pressure data.

 Exact location of all six pressure sensors

 Exact location of LDA measurement

Disclaimer: The provided data, geometry and mesh under Francis-99 workshop series are free for research and education. Upon the usage of the data and the geometry, acknowledgement must be given. “We/I used the test-case provided by NTNU – Norwegian University of Science and Technology under the Francis-99 workshop series.”