Validation of Installation Effect Predictions Through Simulations of Contra-Rotating Open Rotors at Low-Speed Flight Conditions

Contra Rotating Open Rotor (CROR) propulsion systems have been the focus of a number of research projects in recent years, aiming to establish this propulsion system as an economic and environmentally friendly powerplant for future transport aircraft. In the frame of the EU 7th Framework Joint Technology Initiative Smart Fixed Wing Aircraft project, the DLR Institute of Aerodynamics and Flow Technology is participating as an associated partner in the Airbus-led studies of the Contra-Rotating Open Rotor. Due to significant technical challenges in terms of noise emissions, installation effects and certification that still need to be addressed, the numerical activities require the use of sophisticated multidisciplinary analysis tools and approaches covering both aerodynamics and aeroacous- tics. With the availability of high-quality results from aeroacoustic wind tunnel tests of a generic Airbus designed CROR configuration, DLR has initiated an in-depth validation study on the adopted numerical approach to coupled CFD-CAA-simulations utilizing the DLR developed CFD code TAU and the aeroacoustic analysis tool APSIM+. Having previously demonstrated very good quality predictions for an isolated CROR configuration at axial flow conditions, this paper will expand on this work to validate the predictive capabilities for pusher con�guration CROR propulsion systems subject to installation effects due to angle of attack and a pylon wake impingement.