Aerofoil theory

The aerofoil theory has gained increased importance in the calculation of axial blading (impeller, diffuser, blade/vane) For the calculation, the blade/vane is, however, viewed as an aerofoil wing in conjunction with a cascade (see Vane cascade) The lift and drag coefficients and other characteristics of the aerofoil wing dependent on its incidence angle are mainly established experimentally (e. g. in a wind tunnel with three-component force measurements) but can also be calculated theoretically (analytically and/or using CFD).

The aerofoil theory allows the frictionless incompressible approach flow (see Potential flow) of an aerofoil of unlimited width to be calculated, using either conformal representations (transformation back to the flow around a cylinder) or the method of singularities (simulation of vortices, sources and sinks along the aerofoil's centre line or simply of vortices along the aerofoil's contour). In its extended form, the method of singularities can also be applied to vane cascades.