Aerodynamic and Aeroacoustic Analysis of Installed Pusher-Propeller Aircraft Configurations

摘要

In this paper, the aeroacoustic phenomena characteristic of a pusher-propeller configuration and their aerodynamic causes are discussed and analyzed. The work was done in the framework of the European-funded project CESAR (for 'cost effective small aircraft'). The configuration under study is based on an industrially relevant business aircraft design with a wing-mounted pusher propeller, which features a close coupling of the turboshaft-engine 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 unstructured finite volume flow solver (TAU) code with the DLR Ffowcs-Williams-Hawkings code APSIM for a subsequent aeroacoustic evaluation. 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 presented, which highlights the dominant role the engine-jet impingement on the propeller plays for the aeroacoustic characteristics of this type of aircraft configuration. A detailed analysis of specific aspects of the input surface used for the aeroacoustic analysis is made through a comparison between the results achieved using both impermeable and permeable Ffowcs-Williams-Hawkings formulations. The numerical error due to both jet exhaust and propeller wake impingement on the Ffowcs-Williams-Hawkings permeable surface as well as the impact of cutting a hole in this permeable surface to avoid possible issues of these effects are discussed.