Assessment of Flap Side-Edge Fence Noise using SNGR Method

In this paper, the noise reduction efficiency of a flap side-edge fence is revisited and investigated using the stochastic noise generation and radiation (SNGR) method coupled with the Reynolds averaged Navier-Stokes equations (RANS). The configurations are of full scale. The baseline configuration is slotted with double flaps. The fence is attached onto both side edges of the flaps for the purpose of suppressing turbulent vortices induced by the side edge. Furthermore, the efficiency of the SNGR method is assessed as a fast prediction approach for the flap side-edge noise. The noise generation in the SNGR method employs the stochastic model to construct a synthetic turbulent field and takes advantage of the acoustic analogy to formulate the noise sources. The wave equation for the noise radiation is computed by means of the boundary element method (BEM) in frequency space. The BEM takes into account the noise scattered by the surfaces. The fences are found to be efficient for depressing the wake produced by the side edges of the double slotted flaps. Since the energetic vortices contained in the wake are the major contributor of the noise generation, the fence enable an effective noise reduction, particularly in the low frequencies below 200 Hz.