Shedding vortex characteristics analysis of NACA 0012 airfoil at low Reynolds numbers

In this paper, the vortex shedding characteristics been numerically simulated for Re = 1 x 10(4) by computational fluid dynamics (CFD), which caused by flow separation of NACA0012 airfoil. What is more, the variation of vortex shedding structure and the corresponding frequency characteristics of vortex shedding at different angles of attack are studied. The results reveal that with the increase of the angle of attack, the flow state around the airfoil will change from steady state to unsteady state, the vortex structure of the suction surface will become more and more complex with the increase of the angle of attack. In the periodic wake vortex shedding flow field, according analysis of the vortex structure and vortex shedding frequency, the vortex shedding will show 2S (Single) mode (8 degrees similar to 15 degrees) - chaotic state (16 degrees similar to 18 degrees) - 2S (Single) model (19 degrees)- quasi periodic flow (20 degrees similar to 24 degrees) with the increase of angle of attack for alpha>7 degrees. The rising section and falling section of airfoil lift and drag coefficient curves correspond to the vortex shedding and formation respectively. The frequency spectrum corresponding to the lift coefficient can be used to analyze the characteristics of vortex shedding from the perspective of frequency domain. With the increase of the angle of attack, the stability of flow field decreases, and the Strouhal number of vortex shedding frequency decreases basically. The order of the Strouhal number in different flow field states is 2S mode > quasi periodic flow > chaotic state. Among them, most of the Strouhal number corresponding to 2S mode fluctuate around 0.2, and the Strouhal number corresponding to chaotic state and quasi periodic flow fluctuate around 0.02 and 0.07 respectively (C) 2022 The Author(s). Published by Elsevier Ltd.

Automated summary

This paper numerically simulates the vortex shedding characteristics caused by the flow separation of the NACA0012 airfoil at Re = 1 x 10(4) using computational fluid dynamics (CFD). The study investigates the variation of vortex shedding structure and frequency characteristics at different angles of attack. The results show that the flow state transitions from steady to unsteady with increasing angle of attack, leading to a more complex vortex structure on the suction surface. The frequency spectrum corresponding to the lift coefficient can be analyzed to understand the vortex shedding characteristics. As the angle of attack increases, the stability of the flow field decreases and the Strouhal number of the vortex shedding frequency decreases as well.