Modeling fan broadband noise from jet engines and rod-airfoil benchmark case for broadband noise prediction
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This work has two primary parts: (1) an exhaustive literature review highlighting the need and the direction to study broadband noise generation from the fan stage of a modern high bypass ratio turbofan engine, and (2) a benchmark study of noise generation by the flow over a rod and an airfoil in tandem arrangement. The literature review highlights that not all the experimental data has been consistently explained with the theory and thus these gaps are required to be filled in to improve the fan noise prediction during the design phases. The benchmark case provides flow conditions where the upstream located circular rod sheds periodic vortices and creates turbulence which interacts with downstream located symmetric airfoil at zero angle of attack. This interaction produces noise which radiates to farfield. The periodic shedding and the resulting turbulence provides energy to the tonal and broadband components of the total noise. This test case is used to validate a new approach to predict noise in farfield which uses incompressible flow solver, pimpleFoam (part of OpenFOAM), along with Amiet's theory.