Prediction of Broadband Noise: Airfoil in the Wake of a Rod

Numerical Investigation on Vortex‐Structure Interaction Generating Aerodynamic Noises for Rod‐Airfoil Models

“…The oscillation frequency and the amplitude of the lift coefficient are also dependent on the vortex movement. There is obvious connection between the vortex-shedding phase variation and lift amplitude modulation as shown by former research (Phillips, 1956) [7]. Figure 16 gives the vortex structure behind the airfoil.…”

“…The density, interference domain, and the strength of the vortices are all bigger than those of the cylinder. The aerodynamic noise level is also expected to be larger than the cylinder rod-airfoil model according to the connections between the vortex and sound radiation [7,24]. Figure 22 presents the frequency spectrum of the sound pressure level.…”

“…There are mainly four types of numerical aeroacoustic prediction methods [5], including the pure theoretical method [6], the semiempirical method [7], the direct numerical method, and the hybrid method [3,8]. In particular, the Lattice-Boltzmann-Method (LBM) has shown being a very promising technique for far field aeroacoustic prediction (Benjamin Duda, Ehab Fares, 2017), such as LAGOON landing-gear configuration [9] and Jet-plate interaction noise [10].…”

Characterization of the Noise Sources in a Rod-Airfoil Configuration by Means of Time-Resolved Tomographic PIV

“…Vortices shed by the rod partially loose coherence while convected towards the airfoil and undergo strong 3D deformation at interaction with the leading edge (see Boudet 4 and Lorenzoni 6 ) the vortex deformation is believed to be directly responsible for the acoustic emission. In order to visualize such link between vortexairfoil interaction and the relative pressure distribution at the airfoil surface a sequence of instantaneous z-vorticity contours are plotted in Figure 6 (top) with the simultaneous pressure distribution at the surface (bottom).…”

“…Casalino 2 developed an aeroacoustic code based on a porous Ffowcs-Williams and Hawkings in combination with URANS simulations for the acoustic prediction. Improvements in the evaluation of the broadband spectral component were achieved by Boudet et al 3,4 using LES simulations which allowed the detection of the sub-Kármán vortical structures in the cylinder wake embedded in the larger Kármán rollers which are responsible for emission at higher frequency. In both the cases the characterization of the noise sources relied on numerical data obtained by CFD computations.…”