3D PARALLEL SPECTRAL COMPUTATIONS OF FAN NOISE

Abstract. A three-dimensional computational aeroacoustics code has been developed for the simulation of tone noise generated by turbofan engine inlets. The code is based on the linearized Euler equations, rewritten in terms of acoustic potential and solved in the frequency domain. Spatial discretization is performed using a spectral element method. Solution of the linear system of equations is based on the Schur complement method, which is solved using a matrix-free iterative method on multi-processors. A new precon-ditioner, which acts locally on individual subdomains, has been introduced to accelerate the convergence. Moreover, mathematical formulations are presented for implementation of geometric symmetry conditions for general, nonsymmetric wave propagation to further reduce computational cost associated with these types of problems. Numerical results include acoustic propagation from a uniform cylinder as a validation test case and a generic scarfed inlet with close to 2 million grid points, both solved using from 8-48 processors. The code is demonstrated to be robust and ecient in simulating ducted acoustic propagation.