Numerical analysis of broadband noise reduction with wavy leading edge |
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Authors: | Fan TONG Weiyang QIAO Weijie CHEN Haoyi CHENG Renke WEI Xunnian WANG |
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Institution: | 1. School of Power and Energy, Northwestern Polytechnical University, Xi’an 710129, China;2. Key Laboratory of Aerodynamic Noise Control, China Aerodynamics Research and Development Center, Mianyang 621000, China;3. State Key Laboratory of Aerodynamics, China Aerodynamics Research and Development Center, Mianyang 621000, China |
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Abstract: | Large Eddy Simulation (LES) is performed to investigate the airfoil broadband noise reduction with wavy leading edge under anisotropic incoming turbulence. The anisotropic incoming turbulence is generated by a rod with a diameter of 10?mm. The incoming flow velocity is 40?m/s and the corresponding Reynolds numbers based on airfoil chord and rod diameter are about 397000 and 26000, respectively. The far-field acoustic field is predicted using an acoustic analogy method which has been validated by the experiment. A straight leading edge airfoil and a wavy leading edge airfoil are simulated. The results show that wavy leading edge increases the airfoil lift and drag whereas the lift and drag fluctuations are substantially reduced. In addition, wavy leading edge can significantly change the flow pattern around the leading edge and a pair of counter-rotating streamwise vortices stemming from each wavy leading edge peak are observed. An averaged noise reduction of 9.5?dB is observed with the wavy leading edge at the azimuthal angle of 90°. Moreover, the wavy leading edge can mitigate noise radiation at all the azimuthal angles without significantly changing the noise directivity. The underlying noise reduction mechanisms are then analyzed in detail. |
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Keywords: | Aeroacoustics Broadband noise Large eddy simulation Noise control Noise reduction mechanism Rod-airfoil interaction Wavy leading edge |
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