Computation of trailing-edge flow and noise using large-Eddy simulation

Turbulent boundary layers near the trailing edge of a lifting surface are known to generate intense, broadband scattering noise as well as surface pressure fluctuations. Numerically predicting the trailing-edge noise requires that the noise-generating eddies over a wide range of length scales be adequately represented. The large-eddy simulation (LES) technique provides a promising tool for obtaining the unsteady wall-pressure fields and the acoustic source functions. An LES is carried out for turbulent boundary-layer how past an asymmetrically beveled trailing edge of a flat strut at a chord Reynolds number of 2.15 x 10(6). The computed velocity and surface pressure statistics compare reasonably well with previous experimental measurements. The far-field acoustic calculation is facilitated by the integral solution to the Lighthill equation derived by Ffowes-Williams and Hall. Computations have been carried out to determine the far-field noise spectra, the source-term characteristics, and the requirement for the integration domain size. It is found that the present LES domain is adequate for predicting noise radiation over a range of frequencies. At the low-frequency end, however, the spanwise source coherence estimated based on surface pressure fluctuations does not decay sufficiently, suggesting the need for a wider computational domain.