Investigation of the mechanisms of jet engine core noise using large eddy simulation
As further reductions in aircraft engine noise are realized, the relative importance of reducing engine core noise increases. In this work, a representative engine flowpath is studied to examine the mechanisms by which direct and indirect core noise propagate through the engine and affect the far field sound radiation. The flowpath consists of a model combustor, a single stage turbine, a converging nozzle, a near field jet, and far field acoustic radiation. A combination of high fidelity simulations and low order semi analytic models is used to represent the generation and propagation of disturbances through the flowpath. Particular details are provided for LES calculations of combustion chamber, nozzle exhaust flow, and jet noise radiation. A one way coupling procedure is employed for propagating disturbances from one stage of the calculations to the next, and the results show substantial changes in the far field sound directivity and frequency spectra due to fluctuations generated by the upstream engine core.