Fan Noise for a Concept Commercial Supersonic Transport

Supersonic commercial aircraft noise predictions have frequently considered only exhaust noise from the jet engines. Meeting the stringent noise requirements that apply to the subsonic fleet will require reducing jet exhaust noise to the point that fan noise may also require reduction. This report discusses the prediction of fan noise for a supersonic commercial aircraft using existing empirical noise models. Wind tunnel test data from three high pressure ratio fans were compared with the predictions. A two-stage fan was found to agree with predictions to with 1 dB EPNL in a simulated flyover. For a single stage fan, the prediction was found to be higher by nearly 6 dB EPNL. The two types of fans were then scaled to the same thrust and flyover noise was compared. The two-stage fan was found to be louder by 4 dB, although effect on vehicle aerodynamics and sonic boom were not investigated in the present report.