Low-Fidelity Method for Aeroacoustic Design of Pusher Propeller

A low-fidelity model for pusher propeller aeroacoustic analysis was investigated. The model based on the blade element momentum theory was implemented in an unsteady formulation, which allows to calculate time-varying force on the propeller blade subject to a generic inflow velocity. Two test cases were conducted. Firstly, a verification case with simplified aircraft geometry consisting of a main wing and V-tail. Secondly, 3.8-meter wingspan UAV HAASTA, with a V-tail and fuselage, which results in a realistic and complex inflow velocity on a pusher propeller. For both cases, high-fidelity RANS computations without a propeller were carried out to obtain the velocity profile at the position of a pusher propeller, as well as URANS analyses with rotating propellers, used as a reference for low-fidelity method verification. Several off-the-shelf propellers were analyzed for the second test case, to establish the capacity of the low-fidelity approach in design and optimization tasks. Results obtained for both cases confirm the suitability of the low-fidelity method to identify force variations and resulting noise increase. In the simplified case, noise predictions performed using the low-fidelity model match qualitatively results obtained using the high-fidelity CFD. In the second case, significant discrepancies are observed and discussed in the work.