Aerodynamic Installation Effects of Contra-Rotating Open Rotor Engines

Kurzfassung

The main objective of the present work is to evaluate the impact of installation effects produced by wing and high-lift systems on aerodynamic performance of an installed Contra-Rotating Open Rotor (CROR) engine in tractor configuration at low-speed flight conditions. For this purpose, the aerodynamic installation effects of a representative CROR engine configuration are analyzed by numerical and experimental means. Time-accurate unsteady and steady Reynolds-Averaged Navier-Stokes (RANS) Computational Fluid Dynamics (CFD) simulations are performed on isolated and installed CROR configurations, to evaluate the effect of the installation on CROR aerodynamic performance. The results of the simulations are compared to experimental data to demonstrate the capability of the DLR TAU-Code for the simulation of CROR flows and the prediction of aerodynamic performance. A detailed analysis of the numerical results is done to identify key characteristics of the isolated and installed CROR flows to be used for the development of a low-fidelity model able to predict the impact of the powerplant installation on CROR aerodynamic performance. The analytical model is based on the combined Blade Element Momentum Theory (BEMT) adapted for installed CROR configurations. The performance predictions obtained with the model are compared with results from experiments and high-fidelity RANS methods. After an initial validation, a variation of installation parameters is performed to get a better understanding of their effect on aerodynamic performance and to identify trends for an optimal CROR powerplant installation.