A Dynamic-Inflow-Based Induced Power Model for General and Optimal Rotor Performance

A rigorous analytical model for the performance of lightly loaded lifting rotors is developed that combines finite-state dynamic inflow theory with conventional blade element theory. The model captures the behavior of induced power at high advance ratios and provides both general performance and optimum performance subject to specified constraints. The rotor is treated as an infinite number of blades on an actuator disk including reverse flow, root cutout, and inflow feedback. Results provide new understanding of the important role of these effects on rotor power. The model directly yields power constants for a quadratic power model that may be used to quickly calculate induced power. With a sufficient number of control degrees of freedom, induced power by this model approaches the minimum Glauert limit. Results also show that the infinite power peak near an advance ratio of 0.8 (noticed also by previous researchers) can be eliminated with higher harmonic control.