US2341148A - Turbine nozzle - Google Patents

Description

F 1944- R. P. KROON ET A1. 48

TURBINE NOZZLE Filed March 8, 1941.

Rsmcu'r P. Km "R D Guam. ER.

INVENTORS ON as F?- MEY Dv. (7%,M

WITNESSES: -53

Patented Feb. 8, 1944 TURBINE NOZZLE Reinout P. Kroon, Swarthmore, and Charles A.

Meyer, Drexel Hill, Pa., assignors to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa, a corporation of Pennsyl- Vania Application March 8, 1941, Serial No. 382,321

3 Claims. (Cl. 253-48) This invention relates to elastic-fluid turbine impulse stages and it has for an object to reduce shock of the moving blades.

We have found that, where a large proportion of the total turbine pressure drop occurs across the first partial peripheral admission impulse stage, the shock experienced by the moving blades leaving the zone of action of the last nozzle passage of a nozzle group is particularly severe, that is, the very large steam force acting across the blades is at that time suddenly removed. We have greatly reduced shock under these circumstances by restricting admission of steam to the last nozzle passage of the group, and it is a more particular object of the present invention to provide apparatus of this character and serving this purpose.

A further object of the invention is to provide a nozzle construction for an elastic-fluid turbine wherein the nozzles are arranged as adjacent primary and secondary groups with the final and initial nozzle passages thereof common to both groups.

These and other objects are effected by the invention as will be apparent from the following description and claims taken in connection with the accompanying drawing, forming a part of this application, in which:

Fig. 1 is a fragmentary developed sectional view of an impulse turbine stage having the improvement applied thereto;

Figs. 2, 3, 4 and 5 are views similar to Fig. 1 but showing alternative forms of the improvement;

Fig. 6 is a fragmentary side elevational View of 1 the nozzles shown in Fig. '7

Fig. 7 is a view similar to Fig. 1 and taken along the line VII-VII of Fig. 6; and

Fig. 8 is a transverse sectional view of the turbine stage shown in Fig. '7 and taken along the line VIIIVIII of Fig. 6.

In Fig. 1 there is shown an impulse stage, at it, embodying stationary vanes or blades I I and moving vanes I2, the stationary vanes providing nozzle passages l3 and I3a for supplying elastic fluid to the blade passages I2a.

As shown, the nozzle passages I3 are arranged in adjacent primary and secondary groups I4 and I5 supplied from adjacent nozzle chambers I6 and I1 and separated by an intermediate nozzle passage I3a.

With the conventional impulse stage, where the pressure drop across the moving blades is a large percentage of the initial pressure, the shock on the moving blades leaving a nozzle group or zone is very pronounced. This shock may be reduced by limiting the supply of elastic fluid to the final nozzle passage of the group. Instead of the noz zle passages It being arranged as primary and secondary groups, at I4 and I5, and serving alone to supply elastic fluid separately from the nozzle chambers I6 and I! to the blade passages,

there is provided a nozzle passage I3a disposed intermediately of the groups and which communicates with adjacent ends of the chambers I 6 and I! to serve as a common nozzle passage for the latter. In other words, the'pa'ssage i3c functions as the final nozzle passage with the primary nozzle group, at I l, and as the initial nozzle passage with the secondary nozzle group, at I5. Therefore, with steam supplied only to the primary nozzle chamber IS, flow therefrom through the nozzle passage I3a will be substantially less than through each of the nozzle passages I3 of the group at I4, and, in consequence, the shock on moving blades leaving the group will be reduced as compared to the usual arrangement where full flow occurs through the final nozzle passage. While it is inherent that flow through the nozzle passage I3a shall .be less than through the passages I3 when steam is supplied only to the primary nozzle chamber I5, nevertheless, as steam is admitted to the secondary nozzle chamber I1 and such admission is progressively increased, the nozzle passage I3a becomes more and more effective until, with full steam admission to the secondary nozzle chamber, such passage is just about as effective as any of the nozzle passages I3.

In Fig. 1, the nozzle box or chamber partition I8 has its rear edge joined to the inlet edge 22'] of the vane I I separating the nozzle I3a from the adjacent nozzle passages I3 of the primary group. at I4, and elastic fluid is supplied to the nozzle passage Ha through a port 22 formed in the par tition. As the partition I8 provides for substantial communication of the secondary nozzle chamber with the nozzle passage I3a, it will be apparent that such nozzle passage is common both to the primary and to the secondary nozzle chambers, it functioning as the final nozzle passage with the primary group, at It, and as the initial nozzle passage with the secondary group, at I5.

Assuming the admission of steam only to the primary nozzle chamber I6, it will be apparent that the restricted communication thereof with the nozzle passage I3a assures of such limitation of flow through the latter that moving blades leaving the zone of action thereof will have shock ondary nozzle chamber I! and such admission is progressively increased, the common nozzle pas sage I3a for the adjacent primary and secondary nozzle groups becomes more and more effective until, with full steam admission to the secondary nozzle chamber I I, the nozzle passage I3a is just about as eifective as any of the nozzle passages I3. I

In Fig. 2, the structure is somewhat like that already described, the partition I811 is provided with an opening 22a inclined inwardly in the general direction of the initial passage Ho and formed in the junction region between the partition Illa and the inlet edge 20 of the nozzle vane I I.

In Fig. 3, the partition I81) is formed separately from the vanes II, it constituting a part of the nozzle box chambers or structures I6 and I1 and defining passages 23 and 25 for supplying elastic fluid from the nozzle chambers I6 and I! to the nozzle passage I3a.

In Fig. 4, the partition I80 has Wall portions 25 arranged adjacent to the nozzle vanes II, the partition structure having openings 26 and 27 for supplying elastic fluid from the primary and secondary nozzle groups to the common nozzle passage I ta for the adjacent nozzle groups I 4 and I5.

In Figs. 6, 7, and 8, there is shown a further modified form of partition structure for the primary and secondary nozzle chambers. In these views, the primary nozzle chamber It has an outer portion 28 which overlaps radially an inner portion 29 of the secondary nozzle chamber II, the partition structure comprising inner and outer wall elements 3| and 32 arranged adjacent to inlet edges of the vanes I I and being joined by a circumferential element 33. The nozzle passage I3a has a circumferentially-extending partition 34 aligned with the partition 33 and dividing the nozzle passage I3b into inner and outer radial portions.

In Fig. 5, the partition I8d cooperates with a nozzle vane II, as in Figs. 1 and 2, but, instead of providing an opening in the partition for supplying steam from the primary chamber to the nozzle passage I3a, the vane has an opening 36 for supplying steam to such nozzle passage.

While the invention has been shown in several forms, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various other changes and modifications without departing from the spirit thereof, and it is desired, therefore, that only such limitations shall be placed thereupon as are specifically set forth in the appended claims.

What is claimed is:

5 1. In an elastic-fluid turbine, means providing circumferentially-adjacent primary and secondary nozzle chambers separated by a partition structure, a row of moving blades, and a plurality of vanes providing nozzle passages for discharg- 10 ing elastic fluid from the primary and secondary chambers to the blades, said partition structure cooperating with the vanes to divide the nozzle passages into primary and secondary groups separated by an intermediate nozzle passage with the primary and secondary groups supplied with elastic fluid only from the primary and secondary nozzle chambers, respectively, and to provide entrance openings from both the primary and secondary nozzle chambers to the intermediate nozzle passage.

2. In an elastic-fluid turbine, means providing circumferentially-adjacent primary and secondary nozzle chambers separated by a partition structure, a row of moving blades, and a plurality of vanes providing nozzle passages for discharging elastic fluid from the primary and secondary chambers to the blades, said partition structure cooperating with the vanes to divide the nozzle passages into primary and secondary groups separated by an intermediate nozzle passage with the primary and secondary groups supplied with elastic fluid only from the primary and secondary nozzle chambers, respectively, and to divide the entrance to the intermediate nozzle passage into portions open to the primary and secondary nozzle chambers.

3. In an elastic-fluid turbine, means providing circumferentially-adjacent primary and secondary nozzle chambers separated by a partition structure, a row of moving blades, and plurality of vanes providing nozzle passages for discharging elastic fluid from the primary and secondary chambers to the blades, said partition structure cooperating with the vanes to divide the nozzle passages into primary and secondary groups separated by an intermediate nozzle passage with the primary and secondary groups suppli d with elastic fluid only from the primary and secondary nozzle chambers, respectively, and with the entrance to the intermediate nozzle passage open to the secondary nozzle chamber and being joined to the inlet edge of the vane separating the intermediate nozzle passage from the adjacent nozzle passage of the primary group and said partition structure having an opening formed therein at the entrance of said intermediate nozzle passage for supplying elastic fluid from the primary nozzle chamber directly to such nozzle passage.

REINOUT P. KROON. CHARLES A. MEYER.

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