A Numerical Analysis of Wakes Propagation in Inviscid Flow of Turbine

Abstract

The motion of an airfoil or a cascade blade in a nonuniform or unsteady flow can produce important fluctuating forces along the surfaces. This is, for example in turbomachinery, what happens in the case of rotor — stator interactions or inlet distortion or aeroelasticity phenomena. Unsteady wakes passing through cascade channels have a great influence on the flow field [1, 2], especially because they affect boundary layer transition, shock waves and boundary layer stall. Hodson has provided a great amount of information concerning the mechanisms of wakes propagation [3, 4]. The disturbances introduced by the passing wakes cannot be considered as free stream turbulence since the passing wake frequency is much lower than the characteristic frequency of the turbulence. The understanding of the unsteady effects requires reliable models to study the interaction and reflexion effects. The transition will not be considered here. The objective of this study is to understand the physical mechanisms of perturbation propagation through a mean flow field (in a fixed or relative frame) in an interblade channel of a turbomachine. For this purpose we use an algorithm (PROUST) to solve the unsteady 2D compressible Euler equations. As a preliminary test, we applied it to simulate the unsteady flow in the T106 turbine cascade.