低雷诺数下凹坑结构对翼型层流分离影响的数值研究

在低雷诺数Re工况下,翼型表面容易发生流动分离,形成的层流分离泡会导致翼型气动性能恶化,且分离泡在尾缘周期性脱落,会诱发振动,影响叶片的结构安全。文章以NACA4415翼型为例,采用大涡模拟(LES)方法,在低Re下,对光滑翼型及布置凹坑结构翼型的层流分离进行了研究。研究结果表明:凹坑结构对翼型在低Re下出现的层流分离现象有较好的抑制作用,凹坑结构翼型在尾缘的分离流更加贴近翼型表面,凹坑结构翼型尾缘附近的分离涡明显减少;凹坑结构改善了低Re工况下翼型的气动性能,深径比h/d为0.25时,翼型升、阻比达到最大18.23。

Numerical study on the influence of dimples structure on airfoil laminar flow separation under low Reynolds number

Under low Reynolds number conditions,the surface of the airfoil is prone to flow separation.The laminar separation bubbles formed will deteriorate the aerodynamic performance of the airfoil,and the separation bubbles will periodically fall off at the trailing edge,which will induce vibration and affect the structural safety of the blade.Taking the NACA4415 airfoil as an example,using Large Eddy Simulation(LES)method,under low Reynolds number,the laminar flow separation of the smooth airfoil and the airfoil with dimples arranged is studied.The study found that:the dimples structure has a better inhibitory effect on the laminar flow separation of the airfoil at low Reynolds number.The separated flow of the dimples structure airfoil at the trailing edge is closer to the airfoil surface,and the dimples structure airfoil tail.The separation vortex near the edge is nificantly reduced;the dimples structure improves the aerodynamic performance of the airfoil under low Reynolds number conditions.When the depth-to-diameter ratio h/d=0.25,the airfoil lift-to-drag ratio reaches the maximum 18.23.