Conceptual study of micro-tab device in airframe noise reduction: (II) 3D computation

A three-dimensional numerical study is conducted to better understand noise reduction results seen in the previous two-dimensional investigation of the acoustic effects of micro-tab device on airframe noise reduction. Without sacrificing the aerodynamic performance, it is possible to achieve high-lift noise reduction with the application of the micro-tab device attached to the pressure side of the flap surface near its trailing-edge. This study was carried out by numerical hybrid method, which combines Computational Fluid Dynamics and acoustic analogy to predict the farfield noise spectrum. The near-full-scale computational results show that the micro-tab device with reduced deflection of the high-lift devices achieves noise reduction in mid-to-high frequency domain, in particular the range that human beings are most sensitive to. In addition, a parametric study in terms of geometric variation of the micro-tab was also investigated and reported. The three-dimensional results obtained thus far show reduction in noise levels with use of micro-tab.