Multi-stage three-dimensional Navier-Stokes computation of off-design operation of a four-stage turbine

In this paper a 3-D computational methodology for multistage turbomachinery flows is developed, validated, and applied in analyzing the reduced-massflow-rate operation of a 4-stage turbine. The Row is modelled by the 3-D Favre-Reynolds-averaged Navier-Stokes equations using the Launder-Sharma near-wall k - epsilon turbulence closure, which are integrated using an implicit border upwind solver. The computation models the 8 blade-rows, including the tip-clearance gaps of the rotors, using a 6 x 10(6) points grid, and computes the time-averaged flow using mixing-planes between rows. Computational results are compared with measurements for various operating points. After this validation the method is used in a first attempt to analyze the 3-D flow at reduced-massflow operation.