Calculation model for sound propagation in duct with circumferentially non-uniform liner

Ill this paper, an efficient method is described for modeling the wave propagation in a circumferentiaUy non-uniform lined annular duct with mean flow. The cross-section space is discretized by Chebyshev spectral method, through which the equation matrix for physical field and the influence matrix of boundary condition are established. Then the issue is converted to an eigenvalue problem in terms of the acoustic propagation, where the eigenvalues stand for axial wave numbers, the eigenvectors display wave mode profiles. The sound pressure and axial velocity continuity equation is applied at the interface between different segments of the duct, through which the sound field in duct is constructed. It is shown that by using present method, which requires quite less quantity of CPU time compared with 3D numerical method, the superiority in broadband noise reduction of circumferential non-uniform liners is revealed. When sound propagates through the duct lined by circumferential non- uniform liner, the energy is scattered into modes of different orders. What is more, this method is expected to serve as an efficient approach for the optimization of non-uniform liner in the future.