Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02745120 2011-06-30
FLOW MACHINE
Field of the Invention
The invention is directed to a flow machine.
Background of the Art
A flow machine of the type mentioned above is known, e.g., from DE 1 751 075
Al.
In the flow machine which is described in this document and which is
constructed as a
pressure exchanger, two structural component parts cooperate with one another
by means of a
bellows seal so that the bellows seal forms a medium barrier between two
spaces in the flow
machine which adjoin the two structural component parts.
Summary
It is the object of the invention to provide a novel solution for the use of a
bellows
seal in a flow machine.
This object is met by a flow machine (1) with two structural component parts
(10, 20)
which cooperate with one another by a bellows seal (30) so that the bellows
seal (30) forms a
medium barrier between two spaces (40, 50) of the flow machine (1) which
directly adjoin
the two structural component parts (10, 20), characterized in that the flow
machine (1) is
constructed as a gas turbine, wherein one space (40) of the two spaces (40,
50) is a hot-gas
space of a high-pressure stage of the gas turbine.
According to the invention, a flow machine has two structural component parts
which
cooperate with one another by a bellows seal so that the bellows seal forms a
medium barrier
between two spaces of the flow machine which directly adjoin the two
structural component
parts. The flow machine according to the invention is characterized in that
the flow machine
is constructed as a gas turbine, wherein one of the two spaces is a hot-gas
space of a high-
pressure stage of the gas turbine.
It was recognized by the inventors that the sealing area directly at the hot-
gas space of
a high-pressure stage of a gas turbine is extremely vulnerable to leakage
because a levelness
of sealing surfaces cannot be ensured during operation of the gas turbine due
to an irregular
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circumferential distribution in the main gas flow. Further, once a leak has
occurred, it has an
exacerbating effect on the unevenness of the sealing surfaces so that the
leakage effect
increases. Further, there is the risk of overheating of sealing elements and,
as a result, the
loss of preloading or sealing force of the sealing elements.
Leakage can be reliably prevented through the use, according to the invention,
of a
bellows seal in this area.
According to an embodiment form of the invention, the other space of the two
spaces
is constructed as a cooling air space of the high-pressure stage of the gas
turbine.
According to another embodiment form of the invention, the bellows seal has a
first
end portion by which it seals against a first structural component part of the
two structural
component parts and a second end portion by which it seals against a second
structural
component part of the two structural component parts, the first end portion
being fastened to
the first structural component part so that a deformation-tolerant connection
is produced.
On the one hand, the inventive fastening of the bellows seal provides a
reliable
positional stability of the bellows seal and, on the other hand, permits a
certain deformation
of the connection of the bellows seal and first structural component part and,
therefore,
allows the bellows seal to be adapted to specific mechanical parameters while
retaining a
good sealing quality.
The first end portion is preferably welded, soldered, screwed, and/or cemented
to the
first structural component part.
According to yet another embodiment form of the invention, the second end
portion
seals against the second structural component part by area contact based only
on axial
preloading.
In this way, a connection is provided between the bellows seal and the second
structural component part which tolerates movement but is nevertheless tight
against media.
According to another embodiment form of the invention, the first end portion
is
constructed in the form of a flange which proceeds from an outer diameter of a
fold part of
the bellows seal and extends radially outward beyond the outer diameter of the
fold part and
rests on a radially extending sealing surface of the first structural
component part, and the
second end portion is constructed in the form of a flange which proceeds from
the outer
diameter of the fold part and extends radially inward in the opposite
direction of the first end
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portion and rests on a radially extending sealing surface of the second
structural component
part.
Owing to this construction, the first end portion can be fixedly mounted at
the first
structural component part in a particularly simple and convenient manner. The
second end
portion lies inside the outer diameter of the fold and is therefore protected
against damage.
According to another embodiment form of the invention, the first end portion
has an
axially extending connection portion which is connected to the fold part by a
material bond
so that an intermediate space is formed between the fold part and the sealing
surface of the
first structural component part.
The connection portion provides a lever arm so that the first end portion can
deform
to a certain extent in the area of the connection portion when the bellows
seal is axially
loaded and therefore provides deformation tolerance.
According to yet another embodiment form of the invention, a supporting
surface or
guide surface which extends axially in direction of the first structural
component part adjoins
the sealing surface of the second structural component part so that the
supporting surface
provides a radially inward support for the fold part.
Accordingly, a radial buckling of the fold part of the bellows seal and,
therefore,
impairment of preloading and of the sealing effect are prevented in a reliable
manner when
the bellows seal is pushed together axially. Further, the supporting surface
provides an axial
guide for the bellows seal.
According to yet another embodiment form of the invention, the sealing surface
of the
second structural component part, the supporting surface, and the sealing
surface of the first
structural component part extend in such a way that together they form a U-
shaped
circumferential receiving pocket for the fold part of the bellows seal.
In this way, the fold part of the bellows seal is received in such a way that
it is
protected even more reliably against damage and axial buckling.
According to another embodiment form of the invention, the first structural
component part is formed by a stator blade carrier and/or a seal carrier of
the high-pressure
stage of the gas turbine.
Finally, a seal system according to the invention in the form of a bellows
seal in the
high-pressure stage of a gas turbine is used to compensate for large changes
in the axial
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sealing gap, and the tightness of the two structural component parts from one
space (hot-gas
space) to the other space (cooling air space) is achieved through a defined
preloading and
delta p.
As an inventive solution, a deformation-tolerant connection of the two seal
elements
(bellows seal and stator blade carrier) is provided while retaining a good
sealing quality. To
this end, three possibilities are suggested: welding the bellows seal to the
stator blade carrier,
wherein the bellows geometry is designed in such a way that the structural
component parts
and the weld need only tolerate a minimum of stresses; soldering the bellows
seal; and/or a
screw/clamping connection between the bellows seal and stator blade carrier.
Brief Description of the Drawings
The invention will be described in more detail in the following with reference
to a
preferred embodiment form and the accompanying drawing.
Fig. 1 shows a schematic sectional view through a portion of a flow machine
according to an embodiment form of the invention.
Fig. I is a schematic sectional view through a portion of a flow machine 1
according
to an embodiment form of the invention which is constructed as a gas turbine.
Detailed Description
The flow machine 1 has a first structural component part 10 and a second
structural
component part 20 which cooperate with one another by means of a bellows seal
30 such that
the bellows seal 30 forms a medium barrier between a hot-gas space 40 of a
high-pressure
stage (not shown separately) of the flow machine 1, which hot-gas space 40
directly adjoins
the two structural component parts 10, 20, and a cooling air space 50 of the
high-pressure
stage of the flow machine 1, which cooling air space 50 directly adjoins the
two structural
component parts 10, 20.
The first structural component part 10 is formed by a stator blade carrier of
the high-
pressure stage of the flow machine 1. The second structural component part 20
is formed,
e.g., by a housing part of the high-pressure stage of the flow machine 1.
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The bellows seal 30 is preferably produced from a heat-resistant, flexible
metal or
plastic.
The bellows seal 30 has a first end portion 31 by which it seals against the
first
structural component part 10 and a second end portion 32 by which it seals
against the second
structural component part 20.
The first end portion 31 is fastened to the first structural component part 10
by
welding, soldering, screwing, or clamping so that a deformation-tolerant
connection is
produced. In the present embodiment form, the first end portion 31 is welded
on or soldered
on, for example.
To this end, the first end portion 31 is constructed in the form of a flange
which
proceeds from an outer diameter 33a of a fold part 33 of the bellows seal 30
and extends
radially outward beyond the outer diameter 33a of the fold part 33 and rests
on a radially
extending sealing surface 11 of the first structural component part 10.
Further, the first end portion 31 has an axially extending connection portion
31 a
which is joined to the fold part 33 by a material bond or is formed integral
with the fold part
33 so that an intermediate space RI is formed between the fold part 33 and the
sealing
surface 11 of the first structural component part 10.
When the bellows seal 30 is pushed together axially, the fold part 33 can
deform into
the intermediate space R1 by means of a deformation of the connection portion
31 a acting as
a lever arm so that the connection provides deformation tolerance between the
first end
portion 31 and the first structural component part 10.
The second end portion 32 seals against the second structural component part
20 by
area contact that is based solely on axial preloading in the direction of the
second structural
component part 20.
For this purpose, the second end portion 32 is constructed in the form of a
flange
which proceeds from the outer diameter 33a of the fold part 33 and extends
radially inward in
the opposite direction of the first end portion 31 and rests on a radially
extending sealing
surface 21 of the second structural component part 20.
A supporting surface 22 which extends axially in direction of the first
structural
component part 10 adjoins the sealing surface 21 of the second structural
component part 20
so that the supporting surface 22 provides a radially inward support for the
fold part 33.
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As can be seen from Fig. 1, the sealing surface 21 and the supporting surface
22 of the second
structural component part 20 and the sealing surface 11 of the first
structural component part
extend in such a way that together they form a U-shaped circumferential
receiving pocket
for the fold part 33 of the bellows seal 30 so that the fold part 33 is
reliably protected against
damage and axial buckling and is guided axially.
