Computational modelling of a transitional 3D turbine-cascade flow using a modified low-re kappa-epsilon model and a multi-block scheme

A computational finite-volume scheme, based on the structured-grid multi-bl ock approach and incorporating a new variant from the group of low-Reynolds -number k - epsilon models, is applied to the transitional flow in a 3D tur bine cascade. The turbulence model is designed, by reference to a particula r one-equation model, to give the correct variation of turbulence length sc ale as the arall is approached. Its performance characteristics are first d emonstrated through calculations for a transitional flat-plate boundary lay er, prior to its application to the 3D turbine cascade. The characteristics of the cascade flow are examined in detail, especially in terms of the str ucture of the passage vortex and losses arising from turbulence. The latter are shown to be over-estimated relative to the experimental levels due to a premature onset of transition in the blade's boundary layers, especially near the end wall.