Transonic Flow Through a Turbine Stator Treated as an Axisymmetric Problem

Some particularities of transonic flow through a turbine stator near choking limit become apparent by calculating the axisymmetric flow field. At the exit of a stator whose hug-to-tip ratio is reasonably low the flow is clearly subsonic at the outer casing, highly supersonic at the hub. The stream-tubes near the hub exhibit each a Laval throat further upstream. In the transonic zone remarkable values of the radial velocity are brought to light by a relaxation method. After-expansion may begin at subsonic or supersonic velocities. It is characterized by an expansion to overspeed and a formation of wakes the convection of which into the active stream is a cause of losses.