Numerical Prediction of Exhaust Fan-Tone Noise from High-Bypass Aircraft Engines

The ability to accurately predict fan noise is important in designing and optimizing aircraft engine turbofans for low noise emissions. In this paper, a prediction methodology for exhaust fan tone noise analysis is described and validated against various canonical test cases and NASA Source Diagnostic Test (SDT) 1,2 data. The prediction process consists of solving Reynolds-Averaged Navier-Stokes (RANS) equations to compute the fan wake, and calculating the acoustic response of the outlet guide vanes (OGV) to the fan wake using linearized Euler equations. Very good agreement is observed between numerical predictions and semi-analytical results for canonical cases. Detailed comparisons against SDT data are presented for unsteady vane pressure and integrated in-duct exhaust noise power levels. Geometric trends for dierent OGV configurations at various operating conditions are also analyzed.

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