Slat Noise: Aeroacoustic Beamforming in Closed-Section Wind Tunnel with Numerical Comparison

Experiments in closed-section wind tunnels are more suitable for comparisons with numerical results than corresponding experiments in open-section tunnels because well-defined boundary conditions far from the model can be established for the numerics. This paper reports acoustic experimental results on the slat region of a two-dimensional high-lift model. An objective was the production of experimental data to be used in the testing of numerical procedures. Conventional beamforming combined with a deconvolution technique was used. The Reynolds number was approximately 1 million, whereas Mach number and angle of attack ranged from similar to 0.07 to similar to 0.1 and 2 to 10deg, respectively. To prevent interaction between wind-tunnel-wall boundary layers and the model, which causes undesirable three-dimensionality, suction was applied on the wind-tunnel walls, and its effect was investigated. Experimental results for two angles of attack were compared with computational results given by a lattice-Boltzmann solver for the validation of the experimental procedure based on side-wall suction and deconvolved source map computations. The results agreed, in particular regarding the dominant parts of the spectra, and were considered a cross validation of both experimental and numerical approaches. The numerical results were used in the characterization of the flow in the slat cove.