Unsteady Flow, Turbulence and Acoustic Measurements on the Counter-Rotating DLR Turbo Fan Stage CRISPmulti, With and Without Inlet Distortions

Extensive aerodynamic and acoustic measurements were carried out on a counter-rotating turbofan (CRISP) stage under the influence of inlet distortions that are representative of the boundary layer ingestion of an engine embedded in the aircraft fuselage. The unsteady flow field was measured and analyzed using hot-wire anemometry upstream, between and downstream of the rotors, both with and without inlet distortions. Acoustic measurements were carried out using extensive microphone arrays on the intake and exhaust sides of the fan. This article presents exemplary measurement results, which show the significant effect of inlet distortions on turbulence and fan sound excitation.