Noise due to turbulent flow past a trailing edge

A theoretical method [I] for calculating far field noise from an airfoil in an incident turbulent flow is extended to apply to the case of noise produced by turbulent flow past a trailing edge, and some minor points of the theory in reference [1] are clarified. For the trailing edge noise, the convecting surface pressure spectrum upstream of the trailing edge is taken to be the appropriate input. The noise is regarded as generated almost totally by the induced surface dipoles near the trailing edge and thus equal, but anticorrelated, noise is radiated into the regions above and below the airfoil wake, respectively. The basic assumption of the analysis, from which these concepts of appropriate input and dominance of dipole sources follow, is that the turbulence remains stationary in the statistical sense as it moves past the trailing edge. The results show that such trailing edge noise often is quite small, compared say to that produced by typical oncoming turbulence levels of one percent, but that it might be appreciable for an airfoil with a flow separation, or for a blown flap.