Aeroacoustic Properties of Flatback Airfoil at Low Angles of Attack

This study experimentally investigated the aeroacoustic and aerodynamic behavior of a flatback airfoil at angles of attack ranging from −3 ◦ to 10◦. Far-field noise and surface pressure fluctuation measurements were conducted simultaneously. Static pressure measurements were also carried out to investigate the base pressure variation at different angles of attack. The results indicated that the amplitude of tonal noise initially increases and then decreases with the angle of attack, exhibiting a maximum difference of up to 20 dB. A combined analysis of surface pressure fluctuations and acoustic pressure revealed that tonal noise at different angles of attack is primarily influenced by the intensity of surface pressure fluctuations, with a less pronounced effect due to its spanwise coherence. Moreover, broadband noise does not change with the variation of the angle of attack. In terms of base pressure, it was observed that the maximum base drag appears at the angle where the tonal noise reaches the maximum amplitude. However, there was no consistency between the angle of minimum base drag and tonal noise magnitude.