EROS — a common European Euler code for the analysis of the helicopter rotor flowfield

Abstract The helicopter rotor flowfield is one of the most complex and challenging problems in theoretical aerodynamics. Its accurate analysis is essential for the design of rotors with increased performance, reduced vibratory loads and more environmentally friendly acoustic signatures. European rotorcraft manufacturers have an urgent requirement for a rotor aerodynamic prediction tool to be used within the design office on a routine basis and which is capable of capturing rotational phenomena, such as blade tip and wake vortices, and correctly predict the unsteady blade pressures over a range of different flight conditions. The EROS project addresses this requirement by developing a common European rotor aerodynamic system capable of analysing the inviscid rotor flow environment by solving the three-dimensional Euler equations. The method is based on a proven-technology time-accurate Euler formulation on overlapping structured grids (Chimera method). The grid generator provides an all-in-one capability for grid generation guiding the user from the generation of individual component grids to the Chimera domain decomposition through an interactive process which has embedded visualisation and animation capabilities. The cell-centered finite-volume solver adopts a dual-time implicit scheme on deforming grids. Non-conservative interpolation is used to transfer information across grid overlap regions. This article presents the main components of the system and reviews its capabilities through a number of applications.