Numerical Analysis of Structure of Separated Flow on and near Surface of Bowed Stationary Compressor Blades in Annular Cascades at Low Velocity

The separated flow structure on and near the surface of straight and bowed stationary blades of a certain type of compression cascade has been studied in detail by using the topological analyzing method and numerical calculation. It was discovered that bowed blades have an obvious influence on the topological structure of streamlines, at wall surfaces as well as on the structure of the separated flows. The topological structures of the flow field at the suction surface and the lower end-wall corner of a straight blade cascade are shown, together with a proof that the total number of singular points obtained by numerical calculation meets the topological criterion for the surfaces of annular cascades (including blade's surface as well as tip and hub end-wall's surfaces).