Institute of Fluid-Flow Machinery
Polish Academy of Sciences

Abstract

This paper presents details of an investigation of the three-dimensional flow field in a linear turbine cascade with the tip gap. The cascade geometry corresponds to the tip section of a moving blade row of a gas turbine of recent design. Five tip gap widths, including the case of zero gap width, have been investigated experimentally. A five-hole pressure probe was traversed immediately downstream of the trailing edge plane. The measurement results indicate a tip leakage vortex. Further work concerned the computation of the cascade flow field with a finite-element based Navier-Stokes solver. The k/ε-model was used to account for the turbulent behaviour of the flow. The inlet boundary conditions – mean and turbulence quantities – were adopted from the measured inlet flow field. The computational method is able to predict the essential features of the three-dimensional flow field qualitatively. The spatial location of the tip leakage vortex is predicted quite well, but its strength is underpredicted.