The ability to predict the broadband noise due to fluid-structure interaction in the fan-stage of a turbofan engine could enhance engine design. Currently, fully computational hybrid schemes for coupling RANS flow simulations and linearized Euler acoustic simulations offer a potential broadband noise prediction methodology. The success of the hybrid method depends partly on the ability of RANS to accurately predict the turbulent kinetic energy and the integral length scale. The impact of the accuracy of a RANS simulation on the broadband noise prediction is explored. NASAs Source Diagnostic Test (SDT), a 1/5th scale model representation of the bypass stage of a turbofan engine provides the basis for the computations and validations. The RSI (rotor-stator interaction) code is utilized to compute the fan exit guide vane response and exhaust noise due to the interaction with inflow turbulence. The experimental data for the baseline vane SDT case at the approach condition are analyzed using structure functions to obtain the turbulent kinetic energy, dissipation rate, and integral length scale. These results are compared to the solutions provided by four proprietary CFD codes that employ two-equation turbulence models. The CFD simulations are shown to predict the turbulent kinetic energy well, over-predict mean dissipation rate, and capture the integral length scale moderately well. The broadband exhaust noise computed with RSI based on input derived from the various CFD simulations differ and it is shown that the differences are most strongly dependent upon the variation in the estimation of the integral length scale.
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