In the present investigation, Computational Fluid Dynamics (CFD) simulations of semi-installed and fully-installed Contra-Rotating Open Rotor (CROR) propulsion systems are performed. The investigations are part of the activities performed within the OPERO project, where numerical and experimental anaylses are conducted for isolated, semi-installed and fully-installed CROR engines in pusher and tractor configuration, at low- and high-speed flight conditions. The CROR geometry under study corresponds to one of the configurations developed by Rolls-Royce and consists of a wind tunnel scaled 12x9 CROR engine. The generic aircraft configuration is designed by The Boeing Company and consists of a wing-body configuration including high-lift devices. The numerical simulations are performed at low-speed flight conditions for two angles of attack at α = 0° and α = 10° and diverse high-lift devices settings. The CFD results are compared with wind tunnel test (WTT) data to assess the accuracy of the unsteady Reynolds Averaged Navier-Stokes (uRANS) and the steady (Actuator Disk model) approaches for the simulation of rotatory systems implemented in the DLR-Tau code. The results show a good agreement of the predicted performance numbers of the propeller, but some deviations probably due to blade deformation are still observed especially at semi-installed case. The wake measurements downstream of the rotor planes show a very good agreement between CFD and WTT and are in line with the predicted rotor performance. Important conclusions are extracted for the case at angle of attack α = 10° such as the effect of the front blade tip vortex impingement on the aft propeller which is relevant for the acoustics and vibration analysis during the blade design process. The results of fully-installed cases show the impact of the installation of the rotor and aircraft aerodynamic performance and the interactions of the propeller slipstream with the wing and high-lift devices.
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