Theoretical investigation of the operating behaviour of rotating radial bladings due to the variation of the Reynolds number

The plane laminar flow through rotating radial cascades with backwards curved vanes is calculated. The density and viscosity of the fluid are supposed to be constant. Introducing the stream function and the vorticity, the equations of motion and continuity are transformed to non-orthogonal coordinates aligned with the blade contours. For solving the boundary value problem an implicit difference method is used. The operating behavior of the impeller is investigated considering the total head and hydraulic efficiency as functions of the flow coefficient and the Reynolds number. In order to compare the numerial results with experimental data the vanes are described by logarithmic spirals. Taking into account three-dimensional effects the tendencies of theory and experiments are qualitatively well comparable.