Bene ts of Swept-and-Leaned Stators for Fan Noise Reduction

Low-Speed Wind Tunnel. The primary focus of this test was to quantify the acoustic bene ts and aerodynamic performance of sweep and lean in stator vanedesign. Three stator sets were used for this test series. A conventional radial stator set was tested at two rotor–stator axial spacings. Additional stator sets incorporating sweep only and sweep and lean were also tested. The hub axial location for the swept-and-leaned and swept-only stators was at the sameaxial locationas the radialstatorat the smaller rotor–stator spacing (upstream stator location), while the tip of thesemodi ed stators was at the sameaxial location as the radial stator set at the downstream rotor–stator spacing. The acoustic data show that swept and leaned stators give signi cant reductions in both rotor–stator interaction noise and broadband noise beyond what could be achieved through increased axial spacing of the conventional, radial stator. Application of these test results to a representative two-engine aircraft and ight path suggest that about a 3 effective perceived noise (EPN) dB fan noise reduction could be achieved through incorporation of these modi ed stators. This reduction would represent a signi cant portion of the 6-EPNdB aircraft noise reduction goal relative to that of 1992 technology levels of the current NASA Advanced Subsonic Technology initiative