Rotary kinetic fluid motors or pumps – Including destructible – fusible – or deformable non-reusable...
Reexamination Certificate
1999-10-05
2001-04-17
Look, Edward K. (Department: 3745)
Rotary kinetic fluid motors or pumps
Including destructible, fusible, or deformable non-reusable...
C415S173300, C415S173400, C415S174400
Reexamination Certificate
active
06217277
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to rotary engines, and more particularly to turbofan engines having a fan blade lining including a hidden brush seal.
BACKGROUND OF THE INVENTION
In most turbofan engines, a lining is mounted between the engine casing and the first compressor stage or fan blade. The lining provides a tight clearance between the tip of the fan blade and the casing. In order to minimize the consequence of inadvertent contact between the rotating fan blade and the lining, the lining is formed from a material that may be abraded by the blade, and is often referred to as an abradable. An example abradable is disclosed in U.S. Pat. No. 5,655,701.
In the event the blade is struck by a foreign object, such as a bird entering the air intake of the engine, the fan blade may make a radial excursion coming into contact with the lining. As a result of the radial excursion, the lining is shorn by the fan blade tip. For a foreign object of significant size, up to 0.3″ (0.8 cm) of the abradable may be shorn. This, in turn, significantly increases the blade tip clearance, and may cause air recirculation at the blade tip. As a result the fan blade may stall at its outer span, causing serious consequences to the engine, such as engine surges.
Often, engine casings include slots extending into the compressor section near the fan blan. These slots increase the clearance margin before the tip of the blade stalls (referred to as stall margin). However, these slots also reduce overall engine performance.
Accordingly, an improved lining, reducing susceptibility of the engine to consequences of radial excursions of a fan blade is desirable.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an improved rotary engine and an improved fan blade lining for the casing of a rotary engine.
In accordance with an embodiment of the present invention, an engine includes a fan blade, rotatably mounted within a generally cylindrical casing for rotation about a lengthwise extending central axis of the engine. An annular lining is mounted within the casing between a tip of the fan blade and the casing. The lining includes a brush seal that extends around an inner circumference of the casing, and has a plurality of bristles that extend radially inward from the seal. A retaining membrane extends around the brush seal, and prevents the bristles from extending substantially in a radial direction from the brush seal. The retaining membrane is adapted to release the bristles to occupy a radial region between the tip of the fan blade and the casing upon a radial excursion of the fan blade. The bristles, once released, at least partially seal the tip of the fan blade. The invention may be embodied in a rotary engine; and engine lining; or the combination of an engine casing and lining.
Other aspects and features of the present invention will become apparent to those of ordinary skill in the art upon review of the following description of specific embodiments of the invention in conjunction with the accompanying figures.
REFERENCES:
patent: 4398508 (1983-08-01), Moon et al.
patent: 4411594 (1983-10-01), Pellow et al.
patent: 4957411 (1990-09-01), Girault
patent: 5655701 (1997-08-01), Quattrocchi et al.
patent: 5700011 (1997-12-01), Bainachi et al.
patent: 5941685 (1999-08-01), Bagepalli et al.
patent: 0 947 746 (1999-10-01), None
patent: 2333137 (1999-07-01), None
Liu Xiaoliu
Raw John Angus
Astle Jeffrey W.
Look Edward K.
Pratt & Whitney Canada Corp.
Rodriguez Hermes
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