Patent ID: 6375416
Filing Date: 2002-04-23
Classification: F01D,F04D,F05D,Y10S

Abstract:
Apparatus for reducing acoustic radiation which occurs during the operation of turbomachinery comprising:a shroud having a generally cylindrical inner surface; a rotor coaxial with said shroud and including a plurality of uniformly shaped and sized blades extending generally radially outwardly to tip ends proximate to said inner surface at equally spaced circumferential locations; means rotatably mounting said rotor within said shroud; said inner surface of said shroud being circumferentially contoured such that the tip clearance between each of said blades and said inner surface is caused to vary in a periodic manner upon rotation of said rotor so as to create a new periodic unsteady pressure field which is substantially equal to, and out of phase with, an existing periodic pressure field resulting from nonuniform inflow into said blades and results in the radiation from said turbomachinery of reduced blade rate frequency tones, said inner surface of said shroud being a circumferential sinusoidal contour whose periodicity is an integral multiple of the number of said blades.