低雷诺数下翼型气动特性和涡脱落模态分析

Aerodynamic characteristics and vortex shedding patterns analysis of airfoil at low Reynolds number conditions

基于多弛豫格子玻尔兹曼方法对低雷诺数下的二维翼型气动特性和尾流涡脱落特性进行了分析.为了提高计算准确性,采用分块网格细化算法对流场变化剧烈区域进行加密,采用格插值反弹格式处理曲线边界和动量交换方法计算升阻力.通过对及e=1 000时不同格点数目NACA0012绕流的数值模拟,验证了网格的无关性和算法的有效性.在低雷诺数下,流动呈现明显的非定常特性,引起前、后缘分离与再附以及涡脱落现象.研宄发现涡的脱落频率和模态随攻角的变化而变化,存在3种典型的涡脱落模态,即二单(2S)、二双(2P)和双+单(P+S)模态.

The aerodynamic forces and wake vortex shedding characteristics on the low Reynolds number flow past two-dimensional airfoil were proposed by multiple-relaxation-time lattice Boltzmann method.The block mesh refinement was adopted for structured grids in which a finer mesh was needed in parts of the domain characterized by complex flow,and where higher accuracy was required.This new scientific method can effectively solve the complex flow field simulation problems with reasonable accuracy and reliability by simulating unsteady flows around NACA0012 airfoil at R e-\000.The flow exhibits distinct unsteady characteristics,causing separation and reattachment of the leading and trailing edges and vortex shedding at low Reynolds numbers.The results show that accompanying the variations in angle of attack are change in the vortex shedding frequency and the vortex wake pattern»and wake modes,2S(single),2P(pair)and P+S,are observed.