Fluid reaction surfaces (i.e. – impellers) – With heating – cooling or thermal insulation means – Changing state mass within or fluid flow through working...
Utility Patent
1998-07-08
2001-01-02
Look, Edward K. (Department: 3745)
Fluid reaction surfaces (i.e., impellers)
With heating, cooling or thermal insulation means
Changing state mass within or fluid flow through working...
C415S115000
Utility Patent
active
06168380
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a cooling system for the leading-edge region of a hollow gas-turbine blade.
BACKGROUND OF THE INVENTION
Hollow, internally cooled turbine blades with liquid, steam or air as cooling medium are sufficiently known. In particular, the cooling of the leading-edge region of such blades poses a problem.
DE-A1 27 03 815 discloses a cooling system for the leading edge region of a hollow gas turbine blade. The blade used there has a main duct in the leading-edge region, and this main duct is formed by an insert supported on the inner walls of the blade. The leading-edge section is of thicker construction and encloses a cavity. The thickened section is connected to both the blade root and the blade cover plate and serves in particular the torsional rigidity. Via a plurality of bores, the cavity is fed over its height with cooling medium from the main duct, through which flow occurs longitudinally. In this case, the insides of the leading edge in the region of the cavity are impingement-cooled. The cavity is provided at the actual leading edge with through-holes to the outer wall. The cooling medium issuing via the through-holes into the turbine duct thus effects film cooling of the leading-edge region. The bores from the main duct to the cavity are dimensioned in such a way that the pressure drop required for the subsequent film cooling is produced in them.
SUMMARY OF THE INVENTION
Accordingly, one object of the invention is to provide a novel cooling system of the type in which the leading edge is acted upon with pure convection cooling without additional film cooling.
This object is achieved by providing for flow of cooling air through the duct longitudinally over the blade height and the duct is formed with a variable cross section, a means of influencing the coefficient of heat transfer at the leading edge in a desired manner via the selection of the cross section and via the number and dimensioning of the bores is available.
In the case of blades which are provided with a cover plate, it is expedient if the duct merges at its top end into a chamber, which is mounted below the cover plate and is in operative connection with a pressure source, the pressure of which is lower than the pressure in the main duct.
REFERENCES:
patent: 4514144 (1985-04-01), Lee
patent: 4820122 (1989-04-01), Hall et al.
patent: 4820123 (1989-04-01), Hall
patent: 5122033 (1992-06-01), Paul
patent: 5403159 (1995-04-01), Green et al.
patent: 2703815 (1979-02-01), None
patent: WO86/02406 (1986-04-01), None
“Full Surface Local Heat Transfer Coefficient Measurements in a Model of an Integrally Cast Impingement Cooling Geometry”, Gillespie, et al., Jun. 10-13, 1996 presentation at the International Gas Turbine and Aeroengine Congress & Exhibition.
Asea Brown Boveri AG
Burns Doane Swecker & Mathis L.L.P.
Look Edward K.
McDowell Liam
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