| 摘要 |
A rotor arrangement, preferably a fan, comprises a rotor (24, figure 1) having a plurality of aerofoil shaped rotor blades 26 extending radially there from. A casing (30, figure 1) surrounds the rotor blades and has an inner surface 56 which faces tips of the blades 26, the inner surface 56 of the casing 30 further having a circumferentially extending groove 58 arranged axially between leading and trailing edges 44, 46 of the blades 26. The groove 58 extend axially by at least half a wavelength of an unsteady pressure wave, or even at least two and half wavelengths thereof, so as to provide pressure loss and consequently suppress the unsteady pressure waves and reduce blade vibrations. The groove 58 may have a cross-section which is rectangular, triangular, a parallelogram, or part circular. |
