Predicted vs. scale model and flight test UDF engine noise

This paper presents an overview of the development of a frequency-domain, noncompact-source noise prediction model for the unducted fan (UDF) engine. A brief description of the acoustic modeling approach and basic equations employed is given, together with a summary of the aerodynamic characteristics utilized in the noise prediction model. Scale model test results obtained from both low-speed and high-speed wind tunnel measurements are compared with the prediction model, and comparisons of predicted vs measured flight noise characteristics for the full-scale engine are also discussed.