以NACA0012翼型为研究对象,分析在全湍和转捩两种流动状态下分布式粗糙前缘对翼型失速特性的影响规律.使用Menter切应力输运模型和$\gamma - \overline{Re_{\theta t}}$($\overline{Re_{\theta t}}$为转捩动量厚度雷诺数,γ为间歇因子)转捩模型,并分别耦合粗糙度模型和粗糙增长因子输运方程对翼型绕流进行模拟,分析翼型失速特性变化及失速前边界层流动发展状况.结果表明:全湍状态下粗糙前缘不改变NACA0012翼型的后缘失速形态,但失速迎角及最大升力系数显著减小.转捩状态下,粗糙前缘抑制前缘层流分离泡的形成,将翼型的前缘失速类型改变为后缘失速,失速迎角及最大升力系数显著增大.

The influence of the distributed leading-edge roughness on the stall characteristics of NACA0012 airfoil is analyzed in full turbulence flow or transition flow. The Menter shear-stress transport model and the $\gamma - \overline{Re_{\theta t}}$($\overline{Re_{\theta t}}$ is transition momentum-thickness Reynolds number, γ is intermittency)transition model are used to simulate the flow around the airfoil by coupling the roughness model and the roughness amplification factor transport equation respectively. The airfoil stall characteristics and the pre-stall boundary layer development are analyzed. The results show that the trailing-edge stall occurs for the NACA0012 airfoil in full turbulence flow, and the stall characteristic is not changed by the leading-edge roughness. The maximum lift coefficients are significantly decreased with the leading-edge roughness at a lower angle of attack. In transition flow, the leading-edge roughness inhibits the formation of leading edge laminar separation bubbles, and the stall characteristic of airfoil is changed from leading-edge stall to trailing-edge stall. The maximum lift coefficient is significantly increased with the leading-edge roughness at a higher angle of attack.