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Abstract
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In the present study, two complex physical phenomena have been completely simulated and discussed in detail to predict the aerodynamic degradation and aeroacoustic mechanism of a NACA 0012 airfoil in both dry and heavy rain conditions. For this purpose, a CFD-based multiphase model was adopted to numerically investigate the process of formation of the water flm layer on the airfoil surface by coupling the Lagrangian Discrete Phase Model (DPM) and the Eulerian Volume of Fluid (VOF) models. The Ffowcs Williams–Hawkings (FW–H) method was used to predict the aerodynamic noise of the airfoil in a heavy rain condition. The results showed that there were signifcant degradations of the airfoil aerodynamic performance because of water flm formation especially at lower angles of attack. The maximum value of lift-to-drag ratio degradation was 56% at the angle of attack of 2°. Also, the Sound Pressure Level (SPL) increased due to the rain condition. The SPL was sensitive to the raindrop impact on airfoil surface and caused to increase SPL especially in the frequency region less than 2000 Hz. By increasing the angle of attack, the SPL increased especially in the high-frequency region higher than 2500 Hz in rain condition.
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