Steam turbine rotor cascade

Application Challenge 6-12 © copyright ERCOFTAC 2004

Evaluation

Comparison of Test Data and CFD

The results of numerical simulations were compared with experimental data using the interferometric measurements of flow fields and the pressure distribution on the blade surface. For inviscid flows several numerical methods were used, e.g. the TVD explicit MacCormack scheme or the fully implicit new TVD method. Comparison between inviscid solution and experimental results was made using isolines of Mach number from simulation and isolines of density obtained from experiment in the whole flow field. A very good agreement can be seen for the location of the shock wave and reflected shock wave and the position of the recompression domain on the upper side of the blade downstream of the sonic line. The computed pressure distribution on the blade surface. corresponds to experimental data as well. Some differences between experimental and numerical results are possible to observe when H type of grid and quadrilateral cells are used. For the triangular grid very good results were achieved for all used schemes. Likewise good results were obtained for viscous solution based on commercial software FLUENT 5 with a RNG k-eps turbulence model. In this case some disadvantages were observed because non-reflection downstream boundary conditions are not implemented.

Contributors: Jaromir Prihoda; Karel Kozel - Czech Academy of Sciences