Aeroacoustics are located at the interface between the two disciplines of fluid mechanics and acoustics. The study of the aerodynamically generated noise has made considerable progress over the last few years due to the development of numerical techniques.
"Ducat" Aeroacoustic Calculation
An aeroacoustic calculation was performed on the DUCAT configuration (tested at the NLR). This consisted of 16 rods rotating in front of 18 shaped blades (NACA 010-35). The calculation was performed using a laminar approach given the low Reynolds number based on the diameter of the rods (3 mm). A chorochronic approach was used, even though the not insignificant size of the Von Karman vortex streets downstream of the rotor was observed (fig. 1) leading to a partial loss of spatial-temporal properties. However, the interaction mode (1, -2) is clearly present (fig. 2) but a "wave splitting" type acoustic processing remains essential due to the total reflection on the upstream limit condition.
Figure 1 : instantaneous entropy field
Figure 2 : static pressure field (upstream of the rotor)
[vidéo]
European "Turbonoise CFD" Program
The DAAP performed a steady 3D computation on the FANPAC fan configuration and an unsteady Quasi 3D computation on a section of the LNR2 rotor from the Resound program.
Figure 3 : static pressure field
and shear stress lines on the Fanpac rotor
[video 3D]
