Aeroacoustic radiation of a low Reynolds number two-bladed rotor in interaction with a cylindrical beam
Romain Gojon, Nicolas Doué, Hélène Parisot-Dupuis, Bertrand Mellot, Thierry Jardin
Abstract
In this paper, a characterization of a low Reynolds number two-bladed rotor in interaction with a beam is performed using both an experimental campaign performed in an anechoic room and implicit large eddy simulations (iLES) associated with the Ffowcs-Williams and Hawkins (F-WH) analogy. The rotor studied has a NACA0012 blade section profile extruded in the radial direction with a constant chord of 25 mm, a constant pitch of 10° and a diameter of 200 mm. This rotor is tested in interaction with 3 cylindrical beams of different diameters positioned at a distance of 20 mm below the rotor disk plane. The blade passing frequency (BPF) and the high frequency broadband noise appear to not be affected by the presence of the beam. On the contrary, the magnitude of the 2xBPF to 15xBPF harmonics increases up to $30$ dB compared to the case without beam. For the dominant harmonics of the BPF, a dipole-like pattern aligned with the beam can be observed. Numerical simulations were successfully validated against the experimental data for the dominant BPF harmonics and were then used to study the contribution of the rotor and the beam to the noise radiated. It is found that the beam is mainly responsible for the increase in BPF harmonics and their characteristic directivity pattern.