US2701120A - Turbine blade construction with provision for cooling - Google Patents

Description

E. A. STALKER TURBINE BLADE CONSTRUCTION WITH PROVISION FOR COOLING Original Filed Oct. ,22, 1945 Feb. 1, 1955 2 Sheets-Sheet l INVENTOR.

4 ATTORNEYS 1955 E. A. STALKER 2,701,120 TURBINE BLADE CONSTRUCTION'WITH PROVISION'FOR coouuc Original Filed Oct. 22, 1945 2 Sheets-Sheet 2 INVENTOR. Ma. an! MMQMQ M ATTORNEYS United States Patent TURBINE BLADE CONSTRUCTION WITH PROVISION FOR COOLING Edward A. Stalker, Bay City, Mich.

Original application October 22, 1945, Serial No. 623,695, now Patent No. 2,585,871, dated February 12, 1952. Divided and this application July 25, 1949, Serial No. 106,570

4 Claims. (Cl. 25339.15)

My invention relates to blades of fluid machines and in particular to turbine blades.

An object is to provide a slotted blade structure.

It is also an object to provide a slotted blade structure incorporating different materials.

It is a further object to provide a supporting structure for the rotor incorporating the blades which may be simply and economically produced, which has high strength and rigidity in operation and which provides for the proper introduction of the flow of cooling fluid.

I accomplish the above objects by the means illustrated in the accompanying drawings in which Figure l is a side view of a balde;

Figure 2 is a section of the blade along line 2-2 in Figure 1;

Figure 3 is a perspective view of a fragment of the nose piece;

Figure 4 is an exploded view of the blade;

Figure 5 is a perspective view of an alternative blade construction; and

Figure 6 shows a fragment of a rotor incorporating blades like Figure 5.

This application is a division of co-pending application Serial No. 623,695 filed October 22, 1945, now Patent No. 2,585,871.

In my U. S. patent application Serial No. 510,884 filed November 19, 1943 entitled Turbines, now Patent No. 2,489,683, I have disclosed means of cooling turbine blades by interposing a cool stream between the hot gas and the surfaces of the blades. This application discloses a novel blade structure which makes it possible to realize the slot flow with adequate strength in the blade. It also makes possible the use of forged material which is desirable to resist vibration forces. It provides a relatively inexpensive method of constructing a blade, and a further cost reduction is obtained by using a high cost alloy only for the nose piece and a low cost metal for the bulk of the blade.

Referring particularly to the drawings, the blade is composed of a plurality of elements or segments I carrying flanges 2 at either or both ends. These flanges are to be fused together with the airfoil elements of the blade nested together and spaced to provide slots 4 extending spanwise of the blade preferably in both upper and lower surfaces of the blade.

Some of the segments have a trough-like recess 6 on one side and a tongue 8 on the other. The tongue preferably extends the length of the slots and serves to partition the upper surface slots from the lower surface slots.

The lower projections or flanges 2 are for insertion in a slot in the rotor hub. The upper flanges can be butted against each other to form a shroud about the tips of the blades. Although only a single projection is shown on each side it is to be understood that more than one may be used for the hub attachment as is common in turbine practice to provide additional strength.

The spanwise spaces 10 within the blade have access through one end, preferably the inner end, to a source of fluid flow for cooling or improving the aerodynamic characteristics of the blade by the flow out the slots 4. Likewise the nose piece may be provided with a series of spaced holes 11 through which the cooling flow is distributed to cool the entire nose area of the blade.

The tongues 8 also serve to space the elements or segments of the blades to give the proper slot widths when they are fused together. The tongues preferably butt 2,701,120 Patented Feb. 1, 1955 against the forward segment but are preferably not welded thereto.

The flanges 2 of the segments can be fused together by electric welding. They may also be heated by other means and pressed together as a weld. For this purpose induction or gas heating may also be used.

In another form of the invention the elements are assembled in nested relationship as in the form first discussed but they are made from sheet stock as shown in Figures 5 and 6.

In Figure 6 flanges 12 are bent outward to provide a means of holding the blades in the rotor hub at the root end and prongs 14 are shown for attachment of a shroud ring at the tip end.

The blade flanges 12 which are welded to the holding ring 16 have the welds spaced from the corner formed by the walls of the blade and the flange 12. That is, the spots of welding on the flanges are well under the ring 16 where they will not be subject to vibration forces which normally cause cracking about the weld spot. The tongues 23 and 24 (Fig. 5) are inserted into spanwise grooves 25 which restrain the elements from lateral vibration while allowing small relative movement spanwise and chordwise under the action of heating and cooling, this movement relieving thermal stresses which otherwise would occur between the several elements.

The assembled blades are inserted outward through appropriate holes or openings in holding ring 16 having substantially the contour of the root section of the blades, and are then spot-welded, or otherwise bonded to the ring by means of the flange 12 which overlaps the inner surface of the ring adjacent the openings. Retaining ring 18 is made in two or more segments, the flange 12 of the blade being received between such retaining ring and the ring 16 adjacent the openings in the latter, and the assembly is clamped between hub sections 20. Outer ring 22 may be shrunk in place after which prongs 14 are riveted over.

It is a feature of this invention that the fusing of the parts together is done at the ends of the blades so that the slots are open and can pass a cooling stream of air over the whole portion of the length of the blade bathed by the hot motive gas of the turbine.

The blade of Figure 2 exhibits horizontal and vertical partitions within, the tongues 8 being the horizontal ones. These partitions besides serving a structural purpose also conduct the heat away from the external surfaces and dissipate it to the internal flow. Thus they may be considered as'internal cooling fins which divide up the inner flow passages so as to make heat transfer contact with more an.

I have now described suitable embodiments of my invention which are now preferred. It is to be understood however that the invention is not limited to the particular construction illustrated and described and that I intend to claim it broadly as indicated by the scope of the appended claims.

I claim:

1. In an axial flow fluid machine in which an interchange of energy occurs between a fluid and a bladed rotor mounted for rotation about an axis, a ring structure comprising an outer and an inner cylindrically shaped member, said outer member being secured on the perimeter of said inner member adjacent the edges thereof and being spaced apart between said edges to define a space therebetween, said outer member having a plurality of peripherally spaced openings therein each having substantially the contour of the root sections of the blades,

said inner members having a corresponding series of openings, a plurality of hollow sheet metal blades having leading and trailing edges directed radially, each said blade extending radially inward through a said opening in said outer member into said space into contact with both said members with its hollow interior in communication with said openings in said inner members for flow of a fluid therethrough, and means fixing the inner ends of said blades to said ring structure.

2. In an axial flow bladed rotor adapted for the interchange of energy between a fluid and the rotor, a hub assembly comprising side disks spaced apart axially, inner and outer cylindrical members extending axially and positioned between said disks and supported at their side edges thereon, said inner cylinder being spaced from said outer cylinder to define an annular space therebetween, said outer member having a plurality of peripherally spaced openings therein of substantially the contour of the root ends of the blades, and a plurality of hollow sheet metal blades having root end portions positioned in said openings and extending inward into contact with said inner cylindrical member, said blades having radially directed leading and trailing edges and root end flanges within said outer cylinder bonded to one of said members, said flanges extending transversely to the walls of the respective blades adapting the flanges of each said blade to sustain centrifugal load from the blade walls thereof.

3. The combination as defined in claim 2 in which said outer cylindrical member is a sheet metal pressing of the same order of thickness as the walls of said blades.

4. In an axial flow fluid machine in which an interchange of energy occurs between a fiuid and a bladed rotor mounted for rotation about an axis, a ring structure comprising an outer and an inner cylindrically shaped member with the axially inner portion of said outer member in radially spaced relation to said inner member defining an annular space therebetween, said outer member having a plurality of peripherally spaced openings therein each having substantially the contour of the root section of the blades, a plurality of hollow sheet metal blades having leading and trailing edges directed radially, each said blade extending radially inward through a said opening into said space into contact with both said members, flange means on the inner ends of said blades receivable in said annular space to support said blades from said ring structure, and ring-shaped hub means engaging the axially outer portions of said ring structure for supporting said structure for rotation.

References Cited in the file of this patent UNITED STATES PATENTS 841,503 Gelpe et a1. Jan. 15, 1907 875,650 Bassett Dec. 31, 1907 882,521 Jude Mar. 17, 1908 1,178,452 London Apr. 4, 1916 1,245,810 Smith Nov. 6, 1917 1,247,400 1917 1,603,966 Lorenzen Oct. 19, 1926 2,236,426 Faber Mar. 25, 1941 2,337,619 Miller Dec. 28, 1943 2,407,164 Kimball Sept. 3, 1946 2,438,867 Rockwell et a1. Mar. 30, 1948 2,563,269 Price Aug. 7, 1951 FOREIGN PATENTS 225,640 Switzerland May 17, 1943 442,194 Germany Jan. 16, 1921 572,859 Great Britain Oct. 26, 1945 879,000 France Nov. 2, 1942

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