Numerical Study on Tone Noise of Different Thickness Airfoils

Abstract

Based on the Lattice Boltzmann Method(LBM)-Large Eddy Simulation(LES), a direct numerical calculation is presented of tone noise generated by flow past symmetric NACA airfoils with different thickness and at a Reynolds number based on chord of Re = 2.0 × 105. The computation results indicate that the acoustic source of the airfoil mainly at region of trailing edge and the flow separation. For NACA series airfoils with different thicknesses of the same curvature, the increase of thickness could enlarge pressure fluctuation and produce larger scale of vortices. Noise sources are identified in the region of trailing edge and the flow separation. The sound pressure level spectrum analysis shows that the tone noise gradually disappears and the noise spectrum displays broadband features with the increases of airfoil thickness. The noise directivity shows that the sound pressure radiation around the airfoil characteristic the dipole acoustic field. In addition, data analysis shows that the generation of tone noise is closely related to the vortex shedding of the trailing edge of the airfoil.