Acoustic Directivity of the DGEN Aero-propulsion Research Turbofan at Multiple Farfield Array Locations

The NASA Glenn Research Center's DGEN Aero-propulsion Research Turbofan (DART) is based on the Price Induction DGEN380 a small, ~500-lbf thrust class, high-bypass, geared-turbofan engine with a separate flow nozzle. The general characteristics of the DART make it an ideal candidate for utilization as a test bed for engine aeroacoustic research in a relevant performance environment. To provide a baseline acoustic profile for the DART, the system was tested in the NASA Glenn Research Center's Aero-Acoustic Propulsion Laboratory. Acoustic measurements from multiple external arrays locations were acquired over the nominal fan operating range of 50-95%. The acoustic data are evaluated and reported in terms of overall, broadband, and tonal components. The existence of interaction tones (a result of the physics of the dual-spool interactions) are noted and presented. The symmetry of the acoustic directivity was measured in preparation for potential testing in other facilities