Rotor system having alternating length rotor blades and positioning means therefor for reducing blade-vortex interaction (BVI) noise

摘要

A Variable Diameter Rotor (VDR) system (4) having telescoping odd and even blade assemblies (O.sub.b, E.sub.b) wherein the odd blade assemblies define a radial length R.sub.O and the even blade assemblies define a radial length R.sub.E. Each blade assembly (O.sub.b, E.sub.b) defines an internal chamber (64) for accepting a positioning means (70) operative to effect telescopic translation of the blade assemblies (O.sub. b, E.sub.b) such that the radial length R.sub.E of the even blade assemblies (E.sub.b) is equal to the radial length R.sub.O of the odd blade assemblies (O.sub. b) in a first operating mode, and such that the radial length R.sub.E is between about 70% to about 95% of the length R. sub.O in a second operating mode. The positioning means (70) includes a centrifugal restraint assembly (80) disposed within each internal chamber (64) of the rotor blade assemblies (O.sub.b, E.sub.b), a stop surface (64s) formed internally of each internal chamber (64), and an actuation means (90) operative for transpositioning the centrifugal restraint assemblies (80) within the internal chambers (64) such that, in one operating mode, the centrifugal restraint assemblies (80) are disposed in abutting engagement with the stop surfaces (64s) and, in another operating mode, the actuation means (90) is disposed in abutting engagement with the centrifugal restraint assemblies (80) of at least one of the blade assemblies (O.sub.b, E.sub.b).