Numerical simulations of unsteady aerodynamics of helicopter rotor in manoeuvring flight conditions

This article presents a new time-marching fully unsteady method for simulating helicopter rotors in manoeuvring flight conditions. The unsteady wake model is based on Mudryʹs theory which rigorously derives the evolution equation for the wake considered as a vortex sheet from the fluid dynamic equations. The numerical treatment of the sheet with a high-order panel representation allows an accurate simulation of the wake without using numerical regularisation techniques. An unsteady lifting line model, based on Matched Asymptotic Expansion, is used to represent the blade and to extend the concept of induced velocities to unsteady configurations. A first application to the Bo 105 rotor in manoeuvring flight shows that the method is capable to handle such kind of complex configuration.