US 5,344,284 AGranted

Adjustable clearance control for rotor blade tips in a gas turbine engine

AssigneeThe United States of America as represented by the Secretary of the Air Force

InventorsJohn M. Delvaux, William E. Roberts, Jr.

Life of this patent

Estimating the term…

Loading patent…

Abstract

In a gas turbine engine having rotor blades which rotate with the blade tips in proximity with a surrounding rub strip in the engine shroud, an improvement is provided in the form of a radially adjustable rub strip-air bladder assembly. That is, an air bladder is mounted between the rub strip and the shroud and compressed air is fed to or withdrawn from the bladder to radially displace the rub strip so it can follow changes in the rotor blade length and maintain a close clearance with the tips of such blades under varying engine conditions, e.g. accels and decels, while minimizing contact of blade tips and rub-strip. The rub strip-bladder assembly is flexible and can react automatically to radially withdraw in advance of extending rotor blades as a pressure surge suddenly backs through such blades.

Claims10

Dependent claims

In a gas turbine engine having rotor blades mounted on a rotor, which blades rotate in a path with blade tips in proximity with a rub strip in an engine housing, the improvement comprising,

a) said rub strip being mounted around the path of said rotor blades,
b) an inflatable gas bladder mounted in said engine housing behind said rub strip, defining a rub strip-bladder assembly, to displace said rub strip radially relative to said blade tips, said bladder being a flexible open tube having a pair of spaced edges, said rub strip being of substantially rigid material having a pair of bent sides to define a channel on the bladder side thereof, said edges of said bladder fitting within said channel and engaging said bent sides so that the backside of said rub strip caps said bladder and defines an inflatable compartment therewith and
c) means for inflating and deflating said gas bladder to radially move said rub strip to follow said blade tips inwardly and outwardly to maintain a relatively close clearance or gap therewith while minimizing rubbing therebetween.

Dependencies are inferred from the claim text.