Application of wavy geometries for reducing trailing edge instability noise.

Trailing edge noise from lifting surfaces occurs across a wide range of applications, and there is a clear desire to reduce it. At moderate Reynolds numbers, high amplitude instability noise can occur where instability waves in the boundary layer are amplified close to the trailing edge before they scatter as acoustic waves. In this work, aero-acoustic simulations are conducted to demonstrate how wavy wings can be used to reduce trailing edge noise at moderate Reynolds numbers. The simulations are conducted using a hybrid aero-acoustic model, where large eddy simulations are used to compute the acoustic source terms for the acoustic perturbation equations. Wavy wings with different wavelengths are considered to understand how this affects the sound levels. The results show that modest reductions of 4 dB are achieved for wings with a spanwise sinusoidal variation but a substantial reduction of nearly 18 dB is achieved for a wing with a more random spanwise variation. It is further shown that the wavy wings can reduce the drag compared to a smooth wing for the operating condition considered. These preliminary results show that a wavy wing has substantial potential to reduce noise and drag and this warrants further investigation. [ABSTRACT FROM AUTHOR]