An experimental investigation on the near-field turbulence for an airfoil with trailing-edge serrations at different angles of attack

Abstract

The ability to fly silently of most owl species has long been a source of inspiration for finding solutions for quieter aircraft and turbo machinery. This study concerns the mechanisms of the turbulent broadband noise reduction for an airfoil with the trailing edge serrations while the angles of attack varies from+5°to-5°. The turbulence spatio-temporal information are measured with 3D hot-wire. The experiment is carried out in the Northwestern Polytechnical University low speed open jet wind tunnel on the SD2030 airfoil. λ/h = 0.2. It showed the spreading rate of the wake and the decay rate of the wake centerline velocity deficit increased with serrated edge compared to the straight edge, and the three components of velocity changed differently with serrated trailing edge while the angle of attack was changed. It also found that the turbulence peak occurs further from the airfoil surface in the presence of the serrations, and the serrations widened the mix area which allowed the flow mixed together ahead of the schedule.