ROTOR SYSTEM HAVING ALTERNATING LENGTH ROTOR BLADES FOR REDUCING BLADE-VORTEX INTERACTION (BVI) NOISE

摘要

A rotor system (4) having odd and even blade assemblies (Ob, Eb) mounting toand rotating with a rotor hub assembly (6) wherein the odd blade assemblies(Ob) define a radial length RO, and the even blade assemblies (Eb) define aradial length RE and wherein the radial length RE is between about 70 % toabout 95 % of the radial length RO. Other embodiments of the invention aredirected to a Variable Diameter Rotor system (4) which may be configured foroperating in various operating modes for optimizing aerodynamic and acousticperformance. The Variable Diameter Rotor system (4) includes odd and evenblade assemblies (Ob, Eb) having inboard and outboard blade sections (10, 12)wherein the outboard blade sections (12) telescopically mount to the inboardblade sections (10). A positioning means (70) is provided for positioning theoutboard blade sections (12) with respect to the inboard blade sections (10)such that the radial length RE of the even blade assemblies (Eb) is equal tothe radial length RO of the add blade assemblies (Ob) in a first operatingmode, and such that the radial length RE is between about 70 % to about 95 %of the length RO in a second operating mode.