Quadrupole noise generated from a low-speed aerofoil in near- and full-stall conditions
نویسندگان
چکیده
In this paper, direct numerical simulations are performed for low-speed flows past a NACA0012 aerofoil at high incidence angles. The aim is to investigate the significance of quadrupole noise generated due separated shear layers, in comparison dipole emanating from surface. two different components (dipole and quadrupole) calculated by using Ffowcs Williams & Hawkings method approaches: one with solid surface another permeable then estimated approximately taking relative difference between two. current study provides detailed comparisons various observer locations wide range frequencies. also made terms Mach number scaling, which differs significantly theoretical predictions changes rapidly frequency. Additionally, pre-, near- full-stall conditions cross-examined, reveals significant differences contributions, including major source It found that inclusion sources gives rise predicted power level all frequencies (varying 2 10 dB an above aerofoil) compared dipole-only case. contribution far negligible even low subsonic speeds (Mach 0.3 0.4) when stall occurs.
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ژورنال
عنوان ژورنال: Journal of Fluid Mechanics
سال: 2022
ISSN: ['0022-1120', '1469-7645']
DOI: https://doi.org/10.1017/jfm.2022.75