Secondary Flow Control and Streamwise Vortices Formation

The structure of a secondary flow in a linear turbine cascade has been investigated. In order to analyse streamwise vortices configuration and to control their formation two types of side wall boundary layer fences have been applied. Results obtained proved that the streamwise fence reduces significantly spanwise extent of secondary flows. Transverse fence has no such effect but causes very significant change of location and the losses level in a passage vortex. Presented results cast some new light on the contribution of passage vortex, horse shoe vortex and a shear plain in between, to the losses maximum where these flow elements are in direct neighbourhood.