Fluid reaction surfaces (i.e. – impellers) – Specific blade structure – Laminated – embedded member or encased material
Reexamination Certificate
1998-12-17
2001-03-27
Look, Edward K. (Department: 3745)
Fluid reaction surfaces (i.e., impellers)
Specific blade structure
Laminated, embedded member or encased material
C416S22900R, C416S224000, C415S173300, C415S173400, C415S173500
Reexamination Certificate
active
06206642
ABSTRACT:
TECHNICAL FIELD
This invention relates to rotor blades for used in gas turbine engines, and more specifically blades used in the compressor of such engines.
BACKGROUND OF THE INVENTION
The performance of gas turbine engines, particularly those used to power fighter aircraft, can be detrimentally impacted by several factors. One of these factors is referred to as “tip clearance”, which is the gap between the rotating blades and engine case that surrounds the rotating blades. Overall engine performance is particularly sensitive to tip clearance in the compressor section of the engine.
A certain amount of tip clearance is required to accommodate relative movement between compressor blades and the engine case under engine conditions such as surge, aircraft maneuvers, and differences in thermal expansion between the engine rotor and the engine case during engine acceleration and deceleration which decrease the gap. Gas turbine engines typically include outer air seals which are located in the engine case radially outward of each of the rotors. These outer air seals are usually made of an ablative material that is softer than the material on the tips of the blades, so that if the tip of a rotating blade contacts, or “rubs”, the outer air seal, the outer air seal becomes sacrificial and the blade tip sustains little or no damage.
While outer air seals provide protection against blade damage and wear, when a blade tip rubs and grinds away part of the outer air seal, tip clearance increases. Unfortunately, as tip clearance increases, engine performance decreases. Over time, the accumulation of compressor blade tip rubs against the outer air seals can cause substantial deterioration of engine performance.
What is needed is a compressor blade that is capable of multiple rubs with the outer air seal, or the engine case, with no significant increase in tip clearance.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a compressor blade that is capable of multiple rubs with the outer air seal, or the engine case, with no significant increase in tip clearance.
Accordingly, a compressor blade is disclosed having a blade root, an airfoil having a first end, and a second end opposite the first end, the second end having at least one edge, and the airfoil is made of a first material having a first modulus of elasticity. A blade platform connects the blade root to the first end of the airfoil, and a flexible seal is connected to the airfoil adjacent the second end, and the seal is made of a second material having a modulus of elasticity that is substantially less than the first modulus of elasticity.
The foregoing and other features and advantages of the present invention will become more apparent from the following description and accompanying drawings.
REFERENCES:
patent: 5234318 (1993-08-01), Brandon
patent: 5522698 (1996-06-01), Butler et al.
patent: 5628622 (1997-05-01), Thore et al.
patent: 5735667 (1998-04-01), Sanders et al.
patent: 5752802 (1998-05-01), Jones
Holmes Richard A.
Matheny Alfred P.
Twelves, Jr. Wendell V.
Hayes Christopher T.
Look Edward K.
Nguyen Ninh
United Technologies Corporation
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