Progress towards the CFD Computation of the complete Helicopter: Recent results obtained by research centers in the framework of the franco-german Chance Project

This paper describes progress achieved by the research centers (DLR, ONERA, IAG/Stuttgart) in the framework of the long-term Franco-German CHANCE research project for the CFD of the complete helicopter accounting for trim and blade dynamics. The new developments that are surveyed are mainly devoted to: Improvements carried out in order to improve the robustness and the accuracy of the overlapping grid approach (Chimera method): treatment and orphan points for complex geometries, wall treatment for Navier-Stokes computations. Simplification of structured grid generation and adaptation to the solution using either automatic partitioning of overset grids or patched grids. First results for a better resolution of vortices using an automatic vorticity confinement procedure. Application of quasi-steady RANS approach for rotor-fuselage interaction with actuator disk modelling. New developments on fluid-structure coupling with emphasis on the coupling between unsteady Navier-Stokes CFD solvers and dynamic codes for the prediction of performance of main rotors in forward flight.