The ability to accurately predict fan noise is important in designing and optimizing high-bypass aircraft engines 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 data (Heidelberg, L. J., "Fan Noise Source Diagnostic Test-Tone Modal Structure Results," NASA TM-2002-211594, 2002.). The prediction process consists of solving Reynolds-averaged Navier-Stokes equations to compute the fan wake and calculating the acoustic response of the outlet guide vanes to the fan wake using linearized Euler equations. Very good agreement is observed between the numerical predictions and semi-analytical results for canonical cases. Detailed comparisons against the Source Diagnostic Test data are presented for unsteady vane pressure and integrated in-duct exhaust noise power levels. Geometric trends for different outlet guide vane configurations at various operating conditions are also analyzed and found to be in good agreement with data.