ABSTRACT
In the blade element (BE) theory, a rotor with number of blades N is modelled as a disk divided into many concentric annular elemental rings. Figure 1a shows how a disk is used to approximate a rotor of radius R rotating at angular velocity Ω. At radial position r with a width δr, the blades have pitch angle β and lower angle of attack α with incoming flow vector; see Figure 1b.
