A strategy for Contra-Rotating Open Rotors blades design is presented. It is based on several analytical or CFD tools with increasing levels of accuracy. A preliminary design is made with a lifting-line code. These first geometries are then validated and improved with more advanced CFD methods. Steady CFD computations on a blade passage using the mixing-plane technique permit to perform an accurate sensitivity analysis of the main blade geometrical parameters. The key parameters driving the propulsion efficiency are thus identified. Modeling rotor-rotor interactions require more costly unsteady simulations such as chorochronic computations on a blade passage, or chimera/sliding-mesh techniques on the full model for assessing even the installation effects. These methods are performed at the end of the process to validate the robustness of advanced designs to those interactions. The relevance of this strategy is discussed highlighting the results and limitations
