NUMERICAL ANALYSIS OF THREE-DIMENSIONAL TURBINE AIRFOIL DESIGNS

摘要

In this paper the analysis of CFD results of three-dimensional turbine stator vane designs combined with non-axisymmetric endwalls is presented. A Design of Experiments (DoE) method has been used to generate 120 different combinations of the geometrical parameters. By means of a statistical approach the generic correlations and sensitivities of geometrical parameters on the aerodynamic behavior of three-dimensional turbine airfoils are demonstrated. The interpretation of the correlations leads to the finding, that different parameters of the three-dimensional shape fulfill different tasks. The reduction of turbulent kinetic energy and secondary kinetic energy are particularly sensitive to different geometrical parameters. ;By means of the same statistical approach it is also shown that for three-dimensional designs a distinction should be made between losses that occur within the vane passage and losses expected to arise downstream of the evaluation plane. By consideration of this distinction four modified designs have been chosen for a more detailed analysis. The results indicate that the losses produced by the secondary flow can be diminished by means of a three-dimensional shape of the turbine vane. However, this leads to increasing losses occurring at the laminar-turbulent separation bubble on the suction side of the vane. Therefore, non-axisymmetric endwall contouring should be implemented early in the design process to compensate this behavior by adapting the profile pressure distribution.