Validation of CFD simulation with PIV measurements for Open Rotor Noise Predictions

Abstract: CROR means Contra--‐Rotating Open Rotor. Its efficiency is better than usual in aeronautics thanks to its geometry (open rotor and thus high bypass ratio) but also by adding a second rotor. Indeed it enables to recover the swirl loss of the first rotor. However, this engine is rarely used today in civil aviation for acoustic reasons. Studies are carried out in order to reduce its noise emissions. One of its biggest sources is the interaction between both rotors with the impact of first rotor wake on second rotor blades. This report focuses on the aerodynamics of this wake. The goal is to quantify CFD uncertainties comparing them to wind tunnel testing results. PIV (Particle Image Velocimetry) and hot--‐wire measurements were carried out by a team located in Bremen, Germany. They obtained flow mean and turbulent velocities. I was in charge of CFD simulations, processed with RANS equations and two turbulence models. But most of my work was to post--‐process both CFD and wind tunnel testing results with Python Programming and then compare them. In addition, other effects on these mean and turbulent velocities are studied in this report: test variability, blade--‐to--‐blade variability, transition effect and rpm effect.