Large eddy simulation and FW-H acoustic analogy method are performed to investigate the effect of serrated leading edge on rod-airfoil interaction (RAT) noise. A NACA 0012 airfoil with straight and serrated leading edge at zero angle of attack is located one chord length behind a cylinder rod. The leading edge serrations are in the form of sinusoidal profiles. The free stream Mach number is 0.2 and the Reynolds number based on the rod diameter is 48,000. Firstly, the numerical results of straight leading edge airfoil are compared with experimental data, both the flow field predictions and the acoustic results are in good agreement with experiment Secondly, the numerical results are compared between straight and serrated airfoils. The wake of the serrated airfoil is a little bit narrower and weaker and the leading edge serrations efficiently reduce the span-wise correlation coefficient. There is almost no noise reduction effect below the Karman vortex shedding frequency. The reduction of SPL at the Karman vortex shedding frequency is about 2.4 dB. A significant noise reduction is achieved by the serrations over a quite wide frequency range between 2 KHz and 6.5 KHz. It can be noted that the OASPL directivities at different azimuth angles all reduced 2-5.5 dB due to the serrations, which means than the leading serrations are an effective passive flow control method to reduce RAI noise.
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