Effects of Bio-Inspired Surface Roughness on a Swept Back Tapered NACA 4412 Wing

ABSTRACT: This paper presents the overall pros and cons of the effect of surface roughness elements over a NACA 4412 tapered, swept back half wing with a sweep angle of 30º and a dihedral angle of 5º. The tests were conducted at a Reynolds number of 4 × 105 in the IIUM Low Speed wind tunnel. Different roughness sizes and roughness locations were tested for a range of angle of attack. Lift, drag and pitching moment coefficients were measured for the smooth wing and with roughness elements. Surface roughness delays the stall angle and decreases the lift. The wing with the roughness elements located at 75% to 95% of mean chord from leading edge shows minimum drag and maximum lift compared to other locations. Significant increase in the pitching moment coefficient was found for flexible roughness elements. In case of rigid surface roughness, the effect on pitching moment is small.

摘要：本文系统探讨了表面粗糙元对采用NACA 4412翼型、后掠角30°、上反角5°的后掠锥形半翼气动性能的优劣影响。试验于雷诺数4×10^5条件下，在IIUM低速风洞中完成。研究覆盖一定攻角范围，测试了多款尺寸与安装位置各异的表面粗糙元，并分别测量了光滑翼面与加装粗糙元的翼面的升力系数、阻力系数及俯仰力矩系数。结果表明，表面粗糙元可推迟翼面失速攻角，但会降低升力；当粗糙元安装于距前缘75%至95%平均弦长的位置时，相较其他安装位置，该翼面的阻力最低、升力最高。此外，柔性表面粗糙元会显著提升俯仰力矩系数，而刚性表面粗糙元对俯仰力矩的影响则相对微弱。