Measurement and modelling of aero-acoustic installation effects in tractor and pusher propeller architectures

Abstract

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Fast Non-Empiric Tonal Noise Prediction Model for Installed Propulsors

“…If the rotor being modeled consists of multiple blades 𝑁 𝑏𝑙𝑎𝑑𝑒 , the initial location of each line-distributed source is determined assuming an equi-spaced circumferential offset 2𝜋/𝑁 𝑏𝑙𝑎𝑑𝑒 applied to 𝜙 𝑖𝑛𝑖𝑡 . Figure (2) shows the geometrical quantities of interest. The preliminary defined line-distributed sources are then regularised with a two step-procedure, based on the consideration that for straight or piecewise linear curves the radial preliminary source strength value is already known.…”

“…If multiple blades 𝑁 𝑏𝑙𝑎𝑑𝑒 are considered, the initial location of each line-distributed source is determined assuming an equi-spaced circumferential offset 2𝜋/𝑁 𝑏𝑙𝑎𝑑𝑒 applied to 𝜙 𝑖𝑛𝑖𝑡 . Figure (2) is the reference for the geometrical quantities of interest. The source values to be regularised are based on the local sectional lift 𝐿 and sectional drag 𝐷 of the blade airfoil sections, determined from the flow kinematics in the sectional plane shown in Fig.…”

“…Approximately five complete revolutions of the line source are simulated. Table (2) summarises the CAA simulations input parameters. 19) show a stronger acoustic response in the vicinity of the propeller, which could be attributable to the additional contribution of the velocity fluctuations increasing the source computed value.…”

“…The predicted aerodynamic performance indicators from the simplified tool-chain were found to be up to 10% lower than the CFD-predicted counterpart, but consistent with the simplifications introduced. In [2], two distributed electric propulsion configurations were investigated by comparing acoustics measurement data with the results of a tool-chain that included a lifting line solver combined with a free wake model for the blade steady aerodynamic loading, a FWH solver for the direct computation of the acoustics field, and a Boundary Element Method (BEM) solver for the propagation and scattering considering surrounding surfaces. Broadband noise was accounted for by the Amiet semi-analytical model.…”

Numerical Parametric Investigation of Aeroacoustic Installation Effects in a Distributed Electric Propulsion System

“…Regarding noise emissions, some acoustic prediction methodologies have been proposed in recent work from Rizzi et al [1], or Bernardini et al [2] for instance. In particular, a study conducted by the present authors within the European H2020 project ARTEM was aimed at performing some comparisons between measurements inside an aerodynamic wind-tunnel and numerical predictions [3].…”