Rotary kinetic fluid motors or pumps – Method of operation
Reexamination Certificate
2000-05-03
2001-08-14
Verdier, Christopher (Department: 3745)
Rotary kinetic fluid motors or pumps
Method of operation
C415S014000, C415S017000, C415S026000, C415S047000, C415S173100, C415S173200, C415S173300
Reexamination Certificate
active
06273671
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to turbomachinery, and more specifically, but not exclusively, relates to the control of clearance between an impeller and a shroud of a turbomachine.
It is often desirable to minimize clearance between the blade tips of an impeller rotating within a gas turbine engine and a surrounding blade tip shroud to reduce leakage of a working fluid around the blade tips. Frequently, blade clearance minimization is of particular interest for centrifugal compressor stages. One approach to blade clearance minimization has been to provide an abradable coating on the shroud surface that may be rubbed away by blade contact to create a reduced clearance customized to the particular blade/shroud arrangement. Unfortunately, this type of coating may not be suitable for some gas turbine engine applications—especially those where a smooth shroud surface is desired. Indeed, rough, uneven surfaces commonly associated with abradable coatings often adversely impact engine performance. Moreover, it is sometimes desirable to dynamically change clearance during operation, which is not accommodated by such coatings.
Consequently, several actuation schemes have arisen to provide for blade tip clearance adjustment during engine operation. Unfortunately, these systems often include complicated linkages, contribute significant weight, and/or require a significant amount of power to operate. Thus, there continues to be a demand for advancements in blade clearance technology.
SUMMARY OF THE INVENTION
One form of the present invention is a unique blade clearance arrangement for a turbomachine. In other forms, unique systems and methods of turbomachine blade clearance are provided.
A further form of the present invention includes providing a gas turbine engine including a shroud and an impeller. For this form, the impeller is rotated within the shroud to provide a pressurized fluid to operate the engine. The shroud is moved relative to the impeller by electromagnetic actuation to adjust clearance between the shroud and the impeller. As used herein, “impeller” refers to any device arranged to impart motion to a working fluid when rotated. By way of nonlimiting example, an impeller may be formed as one piece, or from multiple pieces and may include one or more blades, airfoil members, or the like, to direct working fluid during rotation.
In still another form of the present invention, a gas turbine engine includes a shroud and an impeller rotatable within the shroud. An electromagnetic actuator operates to move the shroud relative to the impeller to adjust clearance between the shroud and the impeller. A controller may be included to determine a desired amount of clearance and generate an actuation signal to change the clearance in correspondence with this desired amount.
Yet a further form of the present invention includes operating a turbomachine including a shroud and an impeller, and an electromagnetic actuator to adjust clearance between the shroud and the impeller. This clearance is decreased by increasing electrical power supplied to the actuator and is increased by decreasing the electrical power. The elements may be arranged to maximize clearance between the shroud and impeller during a power loss to the actuator to provide for fail-safe operation.
Further objects, features, forms, embodiments, aspects, advantages, and benefits of the present invention shall become apparent from the description and drawings contained herein.
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Allison Advanced Development Company
Verdier Christopher
Woodard Emhardt Naughton Moriarty & McNett
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