Rotary kinetic fluid motors or pumps – With means for re-entry of working fluid to blade set – Axial flow runner
Reexamination Certificate
1999-09-17
2001-07-24
Look, Edward K. (Department: 3745)
Rotary kinetic fluid motors or pumps
With means for re-entry of working fluid to blade set
Axial flow runner
C415S110000
Reexamination Certificate
active
06264425
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a fluid-flow machine for compressing or expanding a compressible medium.
BACKGROUND OF THE INVENTION
Fluid-flow machines of the abovementioned generic type are designed as rotary machines and have moving-blade elements along their axis of rotation, the free moving-blade ends of which face the inner wall of the fluid-flow casing in a freely movable manner. In the case of rotary machines through which the medium to be compressed flows axially relative to the rotor axis, guide-blade plates are normally attached firmly on one side to the inner wall of the casing of the rotary machine and their free end stands freely opposite corresponding contours on the rotor shaft. An essential aspect in the optimization of the compression efficiency or the turbine efficiency of such rotary machines is the reduction of leakage flows, i.e. of flow components, of the compressible medium flowing through the rotary machine, which pass through between the moving-blade ends or guide-blade ends and the contours opposite said ends. So-called labyrinth seals are used in order to reduce or avoid such leakage flows, these labyrinth seals comprising a multiplicity of intermeshing contours, which are able to seal, in a virtually gastight manner, the intermediate spaces between the rotating parts and the fixed casing parts together with guide blade. Thus the leakage flow can be reduced considerably when using labyrinth seals by virtue of the fact that the labyrinth seals themselves are provided with a multiplicity of individual sealing lips, but the disadvantage attached to this form of seal is that, the more labyrinth seals are provided in the interior of a rotary machine and these seals comprise a multiplicity of individual sealing lips, the greater become the frictional forces which, for example, act peripherally from outside on the rotating moving blades, as a result of which the mechanical loading of the rotating parts inside a rotary machine is increased. In addition, it is only rarely possible to accommodate a sufficient number of labyrinth elements for a high sealing effect.
Another solution for the reduction of leakage flows has been pursued in radial-compressor arrangements.
FIG. 2
a
shows a cross section through a radial compressor, which has a central rotor shaft
5
, which is arranged in the interior of the casing
4
of the radial compressor. Connected to the rotor shaft
5
is a nozzle-like contour
11
, through which, in the course of the rotation, preferably air is driven from inside to outside through the nozzle opening
12
by the centrifugal acceleration. Provided opposite the nozzle opening
12
of the contour
11
inside the casing
4
is an outlet opening
13
, through which the compressed air leaves the radial compressor. In order to prevent leakage flows from escaping between the contour
11
and the inner casing
4
through the intermediate spaces
14
, no labyrinth seals are provided, as in the case described above for axial compressors, but rather the fixed casing is deliberately spaced apart from the rotating contour
11
by a gap, so that a leakage flow could occur in principle. However, in order to reduce the leakage flow despite the existing gap, ribs
15
raised above the contour
11
are attached to the outside of the contour
11
(in this respect see
FIG. 2
d
, from which a sectional drawing along section line A—A is depicted in developed form), and these ribs
15
, on account of their radial movement, induce an annular flow in the intermediate spaces
14
, and this annular flow creates inside the intermediate spaces
14
static pressure conditions which correspond to the pressure conditions which prevail in the region of the connecting gaps within the main flow. Due to such a pressure balance between the interior of the intermediate spaces
14
and the main flow, any leakage flows largely cease.
Although a certain proportion of rotary energy must be invested in the generation of an annular flow required in the interior of the intermediate spaces
14
, tests and measurements show that an expenditure of energy in this respect is below the energy which is mainly lost through leakage when using labyrinth seals.
SUMMARY OF THE INVENTION
Accordingly, one object of the invention is to provide an axial-compressor arrangement or axial-turbine arrangement, in such a way that the leakage flow is to be minimized while dispensing with the use, known per se, of labyrinth seals, in which case the adverse frictional effects in labyrinth seals, which not least lead to increased material stresses in the guide blades and moving blades and limit their service life, are to be eliminated. On the contrary, in accordance with the measure known in radial compressors for the reduction of leakage flows, a practicable solution for reducing the leakage flow largely free of contact between the rotating and fixed components of the rotary machine is to be found.
According to the invention, a fluid-flow machine for compressing or expanding a compressible medium, having a rotor on which there is arranged perpendicularly to the rotor axis at least one moving-blade row, the individual moving blades of which have moving-blade ends, which are free on the radial side and face the inner wall of a casing surrounding the rotor, through the interior space of which casing the compressible medium flows axially relative to the rotor axis, is of such a design that an annular-passage system is provided inside the casing, surrounding the rotor, in such a way as to be directly radially opposite the free ends of the moving blades of a moving-blade row. The annular-passage system preferably extends inside the casing of the fluid-flow machine radially around the entire peripheral circumferential margin of a moving-blade row. That region of the annular-passage system which is opposite the moving-blade ends is designed to be open on one side and is bounded by the moving-blade ends in such a way that on either side of a moving-blade row there respectively remains an opening passage, through one opening passage of which the compressible medium, preferably air, flows out of the interior space of the casing, through which the air flows axially, into the interior of the annular-passage system, and through the second opening passage the air discharges out of the annular-passage system into the interior space of the casing again. The abovementioned opening passages correspond in the above case to the intermediate gaps between the rotating and fixed components of the turbine arrangement or compressor arrangement.
To generate an annular flow flowing inside the annular-passage system, the annular-passage system as well as the moving-blade ends, at least in regions which are adjacent to the opening passages, have surface contours which, at those points inside the annular-passage system where the opening passages open out, create pressure conditions which arise due to the formation of a dynamic annular flow inside the annular-passage system and correspond approximately to the static pressure conditions which prevail in the interior space of the casing respectively in the region of the opening passages.
Thus the annular flow is preferably produced inside the annular-passage system in such a way that a small proportion of the compressible medium, preferably air, passing axially through the rotary machine passes through into the opening passage between moving-blade end and casing, preferably through the opening passage which is provided upstream of the moving blade in the direction of flow and, just before the inlet into the annular-passage system, has a flow inner contour which is designed in such a way that the flow passing through the opening passage enters the annular passage with a preferred direction. In this way, an annular flow can be induced inside the annular-passage system opposite the moving-blade ends, and this annular flow produces the desired pressure conditions after appropriate design of the inner contour of the annular-passage system. To this end, the moving-blade ends each
Keller Jakob
Keller Vera and Georg
Asea Brown Boveri AG
Burns Doane Swecker & Mathis L.L.P.
Keller Vera and Georg
Look Edward K.
Nguyen Ninh
LandOfFree
Fluid-flow machine for compressing or expanding a... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Fluid-flow machine for compressing or expanding a..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Fluid-flow machine for compressing or expanding a... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2467898