The experimental investigation of leaned bypass stator vanes impact on the fan model acoustic and aerodynamic performance was carried out for the purpose of noise reduction technology development for advanced turbofan engine. It was studying three versions of bypass duct guide vanes of fan model with pressure ratio 1.54, tip speed 390 m/s and inlet diameter 700 mm. The fan model reference configuration has the blades swept back in the meridional direction (the sweep angle is equal to 18.3 degrees). The blade aspect ratio is equal to 2.13; blades count is equal to 41. The blade has approximately the same profiles along the blade height with the maximal thickness 5.3%. The second configuration of bypass stator was obtained by blade tip and hub profile displacement in circumferential direction clockwise and counter clockwise accordingly in such a manner that the tilt angle between the blade centreline and the radial direction kept constant and equal to +30 degrees. At last, the third configuration of bypass stator was obtained by blade tip and hub profile displacement in circumferential direction counter clockwise and clockwise accordingly in such a manner that the tilt angle between the blade centreline and the radial direction kept constant and equal to 30 degrees. Spectra and directivity diagrams of three versions of fan model measured in the anechoic chamber of C-3A test facility were analyzed. It was obtained, that the stator version leaned in the direction of rotation showed noise reduction relative to the reference stator version; on the contrary the stator version leaned counter to the direction of rotation showed increased noise levels. More noticeable these trends appear at approach mode in rear hemisphere.

The results of an experimental study of the effects of several slot type casing treatment (STCT) configurations on ducted counter rotating fan model (DCRF) noise are given in present work. The casing treatment design parameters such as lattice duty cycle and the cavity height were varied. It is shown that the most important parameter is the duty factor of the lattice. The configuration of STCT, which provides the greatest reduction of sum sound power level of the fan model was installed over the second rotor only and had the highest duty factor.