Fluid reaction surfaces (i.e. – impellers) – Lashing between working members or external bracing – Peripheral
Reexamination Certificate
2001-11-13
2003-02-18
Look, Edward K. (Department: 3745)
Fluid reaction surfaces (i.e., impellers)
Lashing between working members or external bracing
Peripheral
C416S19600R, C416S23100A, C416S500000
Reexamination Certificate
active
06520741
ABSTRACT:
TECHNICAL FIELD
The invention relates to a turbomachine blade provided with a damper-wire hole according to the preamble of claim
1
.
PRIOR ART
In order to avoid inadmissible vibrations of the blades of turbomachines, damper wires or other damping elements, which are accommodated in corresponding holes of the blades, are often used. As a result of the high revolutions, however, increased stresses occur, in particular at the hole margins.
To prevent premature material fatigue, it is known to provide appropriate reinforcement in the hole region of the blades. The contact region between the damper wire and the damper-wire hole during operation of the turbomachine is defined by the distance between the boundary planes of the reinforcement. In this case, this distance, or the length of the contact region, is selected in such a way that both sufficient static strength and dynamic strength is ensured.
However, a problem with such reinforcement of the hole region is the fact that any reinforcement causes a disturbance of the flow in the region of the damper wire and thus reduces the efficiency of the blading. At the same time, the reduction in the efficiency is all the greater, the larger the design of the reinforcement.
SUMMARY OF THE INVENTION
The object of the invention, in attempting to avoid all these disadvantages, is to improve the efficiency of a turbomachine blade which has a reinforced hole for accommodating a damping element.
According to the invention, this is achieved in that, in a device according to the preamble of claim 1, the raised end surfaces of the blade-body marginal region reinforced toward the hole are formed with an acute angle &agr; open toward the leading edge of the blade body and/or with an acute angle &bgr; open toward the blade tip.
The end faces of the reinforced marginal region thus converge in the direction of the blade trailing edge and in the direction of the blade root, so that the size of the reinforced marginal region decreases in the main flow direction of the working fluid. As a result, a turbomachine blade of aerodynamically favorable design in t he region of the hole and having an improved efficiency is obtained.
The two acute angles &agr; and &bgr; are preferably formed within a range of 5° to 30°. It has been found that, with such a configuration, very little disturbance of the flow occurs in the region of the damping elements.
REFERENCES:
patent: 4191508 (1980-03-01), Kuroda et al.
patent: 4268223 (1981-05-01), Anner et al.
patent: 5267834 (1993-12-01), Dinh et al.
patent: 393333 (1924-04-01), None
patent: 2525043 (1976-01-01), None
patent: 4229769 (1994-03-01), None
patent: 1252766 (1960-12-01), None
patent: 2381905 (1978-09-01), None
Mamaev Boris
Phillipsen Bent
Ryabov Evgeny
ABB Turbo Systems AG
Burns Doane Swecker & Mathis L.L.P.
Look Edward K.
Nguyen Ninh
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