Aerodynamic optimization of coaxial rotor in hover and axial flight

Abstract

The paper presents an aerodynamic optimization of a coaxial rotor system in hover and axial flight. For that purpose, a suitable theorem of calculus of variations that provides a new generic result is employed. The analysis is founded on the Blade Element-Momentum Theory, which is based on nonlinear aerodynamics and mutual (interactional) influences that are introduced by the induced downwash field of each rotor over the other. The influence of non-uniformity of the downwash distribution on the optimal design was also studied. The analysis supplies an important insight into the optimal design and efficiency of coaxial rotor systems. The formulation is consistently generic and enables the exploration of a wide range of coaxial configurations. © 2010 by the International Council of Aeronautical Sciences - ICAS.