Turbine-pumps

Abstract

The movable guide vanes of the mobile distributor of the turbine pump are short and so arranged with relation to the fixed guide vanes of the fixed distributor, that when the machine operates as a pump the movable guide vanes bear on the trailing ends of the fixed guide vanes, and when the machine operates as a turbine, the movable guide vanes pivot in a direction to increase the opening necessary to ensure suitable distribution of water over the impeller.

Description

THE INVENTION

This invention relates to turbine-pumps and is more particularly concerned with an improved mobile distributor for such a machine.

It is well known that the distribution components of a turbine comprise a fixed distributor and a movable distributor for adjusting the discharge between complete closure and full opening. It is also known that adjustable pump diffusers comprise a movable section which may be positioned so as to adopt energy recovery to various pump operating conditions. The movable part of such adjustable pump diffusers bears on the concave side of the fixed unit. Turbine-pumps built on the turbine principle to have a fixed distributor and a movable distributor are also known, but in such machines the two distributors thereof have heretofore been constructed to be partly imbricated within each other, i.e., overlapped partly. In all of the aforesaid known machines employing a movable section the length of the movable guide vanes is so calculated that the movable distributor is closed by the movable guide vanes bearing one upon the other. It is also known that in turbine-pump installations a considerable increase in head causes great load fluctuation in the pump, and that the operational loads exerted on the movable distributor vane in such a machine, at such high heads become exceedingly high.

The primary purpose of the present invention is to provide a movable distributor which will decrease the operational loads so that this type of unit may be used in turbine pumps operating under very high heads. In accordance with the invention, this purpose is accomplished by making the guide vanes of the movable distributor short, and so arranging them with relation to the fixed guide vanes of the fixed distributor, that when the machine operates as a pump, such movable guide vanes will bear on the ends of the convex side of the fixed guide vanes, and when the machine operates as a turbine, such movable guide vanes will pivot in the direction which increases the opening necessary to ensure suitable distribution of water over the impeller.

It has been found that when the movable guide vanes of the movable distributor in a turbine-pump are made very short, the hydraulic loads to which they can be subjected are limited. Further, the maintenance of the position of such movable guide vanes due to their bearing on the fixed vanes when the machine acts as a pump, if necessary by prestressing in a manner known to the art, has been found to prevent the vibrations which otherwise result from torque fluctuation when the machine operates under such working condition. These factors insure that the operation of the turbine-pump as a pump will take place under the best possible stability conditions. Moreover, since the required electrical power installed for a turbine-pump is determined by the operation of the machine in pump form, the power gain when the unit acts as a turbine, will because of the displacement of the movable guide vanes in a proper direction, improve the machine economy.

For purposes of illustration, two constructions embodying the invention are described below and shown in the accompanying drawings, in which

FIG. 1 is a horizontal sectional view showing the guide vanes of the fixed and movable distributors of a pump-turbine designed to operate under very high heads; and

FIG. 2 is a similar view of a modification of the vane construction shown in FIG. 1.

Referring more particularly to FIG. 1 of the drawings, the reference numeral 1 designates generally the fixed guide vanes of usual construction provided in the fixed distributor of a pump-turbine. As indicated, such fixed guide vanes are segmently-shaped with one convex side surface and a concave side surface. The movable distributor of the machine is provided with an equal number of movable guide vanes 2 of a thickness substantially equal to that of the fixed guide vanes. Each of the movable guide vanes is rotatable about the axis of a vertical shaft 3 located beyond the trailing end of the associated fixed guide vane. The specific location of each vertical shaft 3 is determined by the mechanical problems which must be taken into account due to the location of such shaft in the movable vane 2 and by the correct positions for the movable vanes when closed and open to attain good hydraulic flow conditions. The shafts 3 are connected in a conventional manner to a shifting ring for positively moving the movable guide vanes to all positions required of such vanes in the operation of the machine and only two of which are shown in the drawings. As indicated in FIG. 1, such connecting means may include a lever 15 connected to each shaft 3 and in turn connected by a link 16 to a shifting ring 17 which may be actuated by a servo-motor (not shown) by means of a rod (not shown) connected tangentially to the shifting ring 17.

It will be noted that the movable guide vanes are very short in comparison with the fixed guide vanes and are too short to cooperate with one another to close the movable distributor, or with the fixed guide vanes to close the passageways 9 between the latter. It will also be noted that the axes of the movable guide vanes 2 are so located with respect to the trailing terminal ends of the fixed guide vanes 1 that in one position thereof the side surfaces 12 of their leading ends 4 bear against the convex surface of the trailing ends 5 of the fixed guide vanes. In this position of the movable guide vanes they cannot be used to close the distributor. The movable guide vanes will assume this position when the machine operates as a pump with water flowing in the distributor passages 9 in the direction of the arrows F. In this position, each movable guide vane 2 will form an extension of the trailing end of the associated fixed guide vane 1 and its side surfaces 8 and 10 are configured to provide a substantial continuation of respectively, the convex and concave side surfaces of the associated fixed guide vane 1, thereby affording no obstruction to the flow of water in the direction F. Since in this position the side surfaces 12 of the leading ends 4 of the movable guide 2 will be pressed firmly against the convex surfaces of the trailing ends 5 of the fixed guide vanes, during such flow of water in the direction F, they will be rendered immovable to any torque fluctuations which might otherwise cause vibration, and will not respond to any hydraulic forces exerted on them tending to cause vibration thereof.

When the machine operates as a turbine the flow is in the direction of the arrow F' and the shifting ring is actuated to shift the links 16 to the dot-dash position designated 16' and through the levers 15 to cause the guide vanes 2 of the movable distributor to take the entry adjustment positions 6 shown in dotted outline in the drawing to ensure a suitable flow adjusted for the turbine delivery rate. The generally convexly-shaped side surface 12 of each movable guide vane 2 is so configured that when such vane is pivoted to the position indicated in dotted outline to increase the opening necessary to obtain a suitable distribution of water over the impeller 11, the opening defined by such side surface 12 and the convex end 5 of the associated fixed guide vane will ensure such distribution without diminution of efficiency.

In FIG. 2 of the drawings, in which like parts have been given the same reference numerals, the side surfaces 12 of the movable vanes 2 instead of bearing against the convex surfaces of the fixed vanes 1, bear against transversely sloping shoulders 7 forming the termini of the trailing ends of such fixed vanes. Thus, each movable guide vane 2, forms a joint with the associated fixed guide vane to provide what may be considered as a composite fixed guide vane when the machine is operating as a pump. This effect is heightened by providing the side surfaces 8 and 10 of the movable guide vane with respectively, convex and concave shapes that will form respectively, a continuation of the convex and concave surfaces of the fixed guide vanes when the side surfaces 12 of the movable guide vanes are pressed against the fixed vane shoulders 7. The face of each sloping shoulder 7 is given a configuration which will cooperate with the movable vane side surface 12 opposing it to provide a suitable passageway for the by-passing additional flow of water when the machine operates as a turbine, as indicated by the dotted line position 6 of the movable guide vane.

Claims

I claim:

1. A reversible pump-turbine comprising a distributor including fixed guide vanes arranged in circumferentially spaced relation around the impeller of the turbine-pump and having outer convexly-shaped sides directed away from the impeller, mobile guide vanes, means for supporting each mobile guide vane intermediate its length for pivotal movement about a fixed axis located in adjacently spaced relation to the trailing end of an associated fixed guide vane, said location of such axis being such that when the reversible pump-turbine is to be operated as a pump the leading end of said mobile guide vane is enabled to be advanced inwardly toward and into contact with the inner trailing end of said associated fixed guide vane reducing the opening between said associated fixed guide vane and that adjacent fixed guide vane which has its side thereof directed toward the impeller disposed in opposed relation to said convexly-shaped side of said associated fixed guide vane, and when the reversible pump-turbine is to be operated as a turbine the leading end of said mobile vane is enabled to be retracted outwardly from said associated fixed guide vane and toward said adjacent fixed guide vane to form a passage between it and said trailing end of said associated fixed guide vane increasing the opening between said adjacent fixed guide vanes to the extent necessary to ensure suitable distribution of water over the impeller, and means operable to advance said mobile guide vanes to advance the leading ends thereof inwardly toward their associated fixed guide vanes to enable the machine to operate as a pump, and to retract the leading ends of said mobile guide vanes away from said associated fixed guide vanes to enable the machine to operate as a turbine, the leading ends of said mobile vanes being shorter than the distance between the opposed sides of said adjacent fixed guide vanes and said mobile vanes being of such length and so arranged in the distributor that they are unable to close the passageways between said adjacent fixed guide vanes, or to cooperate to close the distributor.

2. A turbine-pump as defined in claim 1, in which in the advanced position of the leading end of each movable guide vane, such leading end bears on the convex face of the trailing end of the associated fixed guide vane.

3. A turbine-pump as defined in claim 1, in which in the advanced position of the leading end of each movable guide vane, the outer side surface of such movable guide vane forms a continuation of the convexly-shaped side of the associated fixed guide vane.

4. A turbine-pump as defined in claim 3, in which said outer side surface of said movable guide vane is convexly-shaped and forms a strictly continuous profile with the convexly-shaped side of the associated fixed guide vane.

5. A turbine-pump as defined in claim 1, in which the terminus of the trailing end of the associated fixed guide vane is shaped to provide a slanting shoulder against which said leading end of the movable guide vane bears.

6. A turbine-pump as defined in claim 1, in which the surface of the leading end of each movable guide vane engageable with the surface of the trailing end of the associated fixed guide vane in the advanced position of such leading end, and said latter trailing end surface are configured to define a fluid passageway for by-passing additional flow of water in the retracted position of said movable guide vane.