On the Deviation of Outlet Flow Angles Caused by Secondary Flows in Turbine Cascades (1st Report)

Abstract

This report suggests a simple formula for calculating the mean outlet flow angle deviation caused by the secondary flow in turbine cascades of semi-infinite span, assuming the secondary vortices concentrated on their centroid, then deriving secondary velocities along the trailing edges and computing the actual vane circulation using Smith's equation. As a result, the following conclusions are obtained ; (1) Deviation of outlet flow angle increases with the increase in the inlet flow angle. (2) Deviation of outlet flow angle increases with the increase in the spacing of cascade, especially in impulse cascade of large camber angle. (3) Calculated results were compared with some experiments and fairly good coincidence was obtained except the effect of passage vortex of impulse cascade being pushed towards the mid-span.