Effect of Different Turbulence Models on the Numerical Analysis of Axial Flow Turbine Stage of a Typical Turbofan Engine

3D NS analysis is routinely used in the design and analysis of modern turbine stages in the recent days. One of the key parameters which influence the results of the numerical analysis is the turbulence models. Thus the choice of the turbulence models plays an important role in the 3D NS analysis. In addition to the turbulence models, the grid resolution in the boundary layer also considerably influences the results of the analysis. The objective of the work is to study the choice of turbulence models, inlet free stream turbulence intensity, the eddy length scales and values of y+ on the performance of an axial flow turbine stage of a typical turbofan engine by using ANSYS CFX 3D NS code. The Reynolds Averaged Navier – Stokes (RANS) equations are solved. The governing equations are discretized using finite volume method. The solution algorithm is based on an implicit scheme coupled with multi-grid. Analyses are carried out using three different turbulence models namely k-ε, k-ω and SST models. It is observed that there is no appreciable change in the turbine performance parameters for the different turbulence models. However, the k-ω and SST models predict a drop in the turbine efficiency of 0.4 % as compared to other models. The effect of various inlet free stream turbulence intensity levels and length scales on the performance parameters is also presented.