초록 ▼

In order to combat flutter in rotor blades rotating within a duct bounded by a duct wall, the duct wall incorporates cavities tuned for resonance to a known flutter frequency. The cavities, which may comprise tubes immediately underlying a facing sheet of the duct wall, are arrayed around the circum

In order to combat flutter in rotor blades rotating within a duct bounded by a duct wall, the duct wall incorporates cavities tuned for resonance to a known flutter frequency. The cavities, which may comprise tubes immediately underlying a facing sheet of the duct wall, are arrayed around the circumference of the duct wall and communicate with the duct through openings in the duct wall near the tips of the blades. Flutter energy from the blades is transferred directly to the cavities by pressure waves and produces resonance in the cavities so that the flutter is damped aerodynamically. The invention is applicable to fans in turbofan engines.

대표청구항 ▼

An axial gas flow machine comprising: a duct wall bounding a duct, a rotor having blades mounted thereon for rotation within said duct, said blades being subject to a flutter at a known flutter frequency, said flutter giving rise to non-propagating pressure waves of less frequency than pressure wave

An axial gas flow machine comprising: a duct wall bounding a duct, a rotor having blades mounted thereon for rotation within said duct, said blades being subject to a flutter at a known flutter frequency, said flutter giving rise to non-propagating pressure waves of less frequency than pressure waves of far field noise frequencies in gas flow past said blades, said blades during said rotation having radially outer tips which sweep out a path adjacent said duct wall as said rotor rotates, said path having a leading edge and a trailing edge defined with respect to said gas flow and corresponding respectively to leading edges and trailing edges of said blades, said duct wall having openings therein which openings are circumferentially spaced around said duct at least radially adjacent said path of said radially outer tips of said blades, said duct wall further incorporating resonator cavities tuned for resonance to said known flutter frequency, each one of said cavities being in communication with said duct by a corresponding one of said openings, whereby flutter energy from said radially outer tips of said blades is transferred by said non-propagating pressure waves directly into said cavities substantially only as the tips of said blades pass said openings, resonance being produced in said cavities with consequent aerodynamic damping of said flutter in said blades.