Rotary kinetic fluid motors or pumps – Working fluid passage or distributing means associated with... – Vane or deflector
Reexamination Certificate
2000-02-17
2001-05-15
Ryznic, John E. (Department: 3745)
Rotary kinetic fluid motors or pumps
Working fluid passage or distributing means associated with...
Vane or deflector
Reexamination Certificate
active
06231304
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION AND PRIOR ART
The present invention relates to an outlet device for a flow machine according to the preamble of claim
1
.
The invention will now be described in relation to a gas turbine. However, it is to be noted that the invention also is applicable to other types of flow machines, such as pumps, compressors, etc.
Usually, gas turbines comprise a diffuser arranged downstream of the turbine and shaped as a channel having an annular crosssection with an increasing cross-sectional area in the flow direction. The object of the diffuser is to decrease the velocity of the flow from the turbine and transform such a great part as possible of the kinetic energy of the flow to useful pressure energy. Downstream of the diffuser, there is a so called outlet housing, the object of which is to collect the flow from the diffuser to an outlet passage arranged to guide the flow from the turbine, often essentially perpendicularly in relation to the rotational axis of the turbine. In order to guide the flow from the diffuser into the outlet housing, it is known to let the diffuser terminate in an annular guide vane arrangement guiding the flow outwardly in a radial direction from the diffuser. In order to make it possible to collect and redirect the outwardly directed flow in the outlet housing without any appreciable losses of pressure, the outlet housing has to have a certain dimension, i.e. the radius at least in a lateral direction will be essentially larger than the radius of the diffuser and the turbine. A great lateral radius, i.e. a width, of the outlet housing means that the gas turbine plant requires a lot of space.
U.S. Pat. No. 5,188,510 shows an outlet device for a gas turbine, comprising an expanding diffuser channel for a flow from the gas turbine and an outlet housing provided downstream of the channel of the diffuser and guiding the flow outwardly in a direction essentially perpendicular to the rotational axis of the gas turbine. The outlet housing comprises an outlet baffle and a guide vane extending in the circumferential direction, which contribute to divide the flow into a plurality of different part flows through the outlet housing in order to enable an adaptation of the shape of the outlet housing to different kinetic energies of the different part flows.
SUMMARY OF THE INVENTION
The object of the present invention is to remedy the above mentioned problems and provide an outlet device which has an outlet housing with a reduced radius, at least in one direction, while maintaining the performance thereof.
This object is achieved by the outlet device initially defined and characterised in that the guide vane arrangement is arranged to redirect outwardly a first part flow of the flow from the channel into a first chamber of the outlet housing, and that the outlet device comprises at least one bypass channel, extending from the channel through said guide vane arrangement and arranged to guide a second part flow of said flow to bypass said guide vane arrangement to a second chamber of the outlet housing. By such an bypass channel extending through the guide vane arrangement, the radius or the width of the outlet housing may be decreased in the area where the bypass channel extends, because no flow will be directed outwardly in this area but continue rearwardly into the second chamber of the outlet housing. By the rearward direction is meant the direction towards the outlet of the flow machine and by the forward direction is meant the direction towards the inlet of the flow machine.
According to an embodiment of the invention, the first chamber and the second chamber are connected by a common outlet passage for said first and second part flows. In such a way, both the part flows may be reconnected to a common outlet flow.
According to a further embodiment of the invention, said bypass channel comprises at least one guide vane, arranged to direct at least a part of said second part flow through the second chamber to the outlet passage. In such a way, a desired flow direction may be obtained in the second chamber. Furthermore, the first chamber and the second chamber may be arranged to guide said first and second part flows, respectively, into the outlet passage in such a way that the flow directions of said part flows are essentially parallel through the outlet passage. Thereby, it is possible to provide a commonly outlet flow which is essentially clear of vortexes.
According to a further embodiment of the invention, said bypass channel extends essentially straight through the guide vane arrangement. By such a bypass channel the radial extension of the bypass channel may be reduced to a minimum. Nevertheless, the housing may have such a shape that the flow from its upper half may pass upwardly without being throttled.
According to a further embodiment of the invention, the outlet device comprises a rear wall member of the channel, wherein the guide vane arrangement is provided on the side of the wall member which faces the channel and a second chamber is provided on the side which faces away from the channel. Consequently, it is possible to increase the length of the outlet device as compensation for the decreased width. Thereby, the bypass channel extends through the rear wall member.
According to a further embodiment of the invention, the channel seen in a cross-section has an essentially annular shape. Advantageously, the outlet device may comprise two bypass channels which, seen in a section through the channels, are provided essentially diametrically in relation to each other. Such a symmetrical construction of the outlet device is preferable from a viewpoint of the flow.
According to a further embodiment of the invention, the guide vane arrangement is arranged to redirect outwardly said first part flow and at least partly forwardly in at least one first area of the extension of the guide vane arrangement in a circumferential direction. By guiding the flow forwardly in such a way, the formation of vortexes in the first chamber of the outlet housing may be essentially decreased. In certain applications, it may be advantageous to let the guide vane arrangement be arranged to redirect outwardly said first part flow in a second area of the extension of the guide vane arrangement in the circumferential direction. Thereby, the second area may be located on the side of the channel, which faces the outlet passage, and the first area on the side of the channel, which faces away from the outlet passage.
According to a further embodiment of the invention, the channel comprises support members, extending radially outwardly in the channel and an essentially plane plate is provided essentially in parallel to an axial plane upstream or downstream of each of the support members. By such a plate, the flowing of the flow through the channel may be guided in an essentially axial direction through the channel.
REFERENCES:
patent: 3149470 (1964-09-01), Herzog
patent: 4214452 (1980-07-01), Riollet et al.
patent: 5188510 (1993-02-01), Norris et al.
patent: 5203674 (1993-04-01), Vinciguerra
patent: 5518366 (1996-05-01), Gray
patent: 5707208 (1998-01-01), Kreitmeier
patent: 0 345 700 (1989-06-01), None
patent: 1 105 245 (1955-06-01), None
patent: 1-178706 (1989-07-01), None
patent: 86087 (1957-08-01), None
ABB Stal AB
Connolly Bove Lodge & Hutz LLP.
Ryznic John E.
LandOfFree
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