Numerical Investigation of the Clocking Effects in a Multistage Turbine

Abstract

The paper presents a numerical study on turbine clocking using a stator/rotor/stator model configuration of equal pitches. The results of time accurate flow calculations for four clocking positions are compared. The unsteady, two dimensional Reynolds averaged equations are solved using a one-equation turbulence model by Spalart and Allmaras. In absence of a transition model, the flow is assumed to be fully turbulent. In a first analysis of the unsteady data, emphasis has been put on the loss production of the clocked stator. A Fourier decomposition of the specific entropy at the stator entry and exit is discussed. It is shown that clocking determines the degree of interaction of a stator with the wake of another upstream stator for a given rotor speed. Further, clocking has little upstream influence.