Volume 39, Number 4, August 2021
|Page(s)||721 - 730|
|Published online||23 September 2021|
Effect of turbulence intensity and gradient of turbulence intensity on airfoil aerodynamic characteristics at low Reynolds number
School of Aeronautics, Northwestern Polytechnical University, Xi’an 710072, China
Based on the complex flow field of vertical takeoff and landing (VTOL) aircraft with distributed propulsion, the influence of the turbulence intensity and gradient of turbulence intensity on the aerodynamic characteristics of two-dimensional airfoil under low Reynolds number was studied by solving the unsteady Reynolds averaged Navier-Stokes (URANS) Equation based on the c-type structural mesh and γ-Reθt transition model. The aerodynamic characteristics of NACA0012 airfoil at different turbulence intensities and Reynolds numbers are simulated and compared with the experimental data, which verifies the reliability of the low Reynolds number calculation method. Meanwhile, the effects of the different low Reynolds number and gradient of turbulence intensity on the aero-dynamic characteristics of airfoil are studied, and the effect mechanism of the turbulence on the flow field around airfoil is analyzed. It shows that the flow characteristics of the airfoil with high turbulence or Reynolds number are more stable, the separation bubble size is smaller, the flow separation is delayed, and the stall angle of attack is larger, but the effect of the two mechanisms on the earlier transition is different. The influence of the turbulence gradient on the airfoil is limited by the Reynolds number, and the flow separation, transition and reattachment of the airfoil with high turbulence gradient are advance. The generation and evolution of the laminar separation bubble are closely related to the turbulence intensity and Reynolds number, and its scale and location also affect the aerodynamic characteristics of the airfoil.
Key words: vertical takeoff and landing (VTOL) / unsteady Reynolds averaged Navier-Stokes (URANS) / low Reynolds number / turbulence intensity / laminar separation bubble / transition
关键字 : 垂直起降 / 非定常 / 低雷诺数 / 湍流度 / 层流分离泡 / 转捩
© 2021 Journal of Northwestern Polytechnical University. All rights reserved.
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