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

Turbulent boundary layers near the trailing edge of a lifting surface are k nown to generate intense, broadband scattering noise as well as surface pre ssure fluctuations. Numerically predicting the trailing-edge noise requires that the noise-generating eddies over a wide range of length scales be ade quately represented. The large-eddy simulation (LES) technique provides a p romising tool for obtaining the unsteady wall-pressure fields and the acous tic source functions. An LES is carried out for turbulent boundary-layer ho w past an asymmetrically beveled trailing edge of a flat strut at a chord R eynolds number of 2.15 x 10(6). The computed velocity and surface pressure statistics compare reasonably well with previous experimental measurements. The far-held 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 r adiation over a range of frequencies. At the low-frequency end, however, th e spanwise source coherence estimated based on surface pressure fluctuation s does not decay sufficiently, suggesting the need for a wider computationa l domain.