Aerodynamic and aeroacoustic analysis of installed pusher propeller aircraft configurations (Section 7.2)

Abstract

the aeroacoustic phenomena characteristic of a pusher-propeller cofiguration and their aerodynamic causes are discussed and analyzed. The configuration under study is an industrially relevant design with a wing-mounted pusher propeller, which features a close coupling of the turboshaft engines exhaust nozzles and a five bladed propeller. An established numerical analysis approach is applied in this study, which couples a high-fidelity unsteady aerodynamic simulation using the DLR TAU-Code with the DLR APSIM Code for a subsequent aeroacoustic evaluation. APSIM computes the sound propagation into the fareld based on the Ffowcs-Williams/Hawkings (FW-H) equations. A detailed analysis of the contributions of various components of the installation as well as flight condition specific parameters toward the overall noise generation by the propeller is studied. A detailed analysis of specific aspects of the numerical approach for the aeroacoustic analysis is made through a comparison between the results achieved using both a FW-H impermeable and permeable formulation. The numerical error due to both jet exhaust and propeller wake impingement on the FW-H permeable surface as well as the impact of cutting a hole in this permeable surface to avoid possible issues of these effects are discussed.