GUIDE BLADE AND STATIONARY CASCADE FOR A TURBOMACHINERY

Abstract

 The present invention is related to a guide blade (1) for a turbomachinery, whereby the guide blade (1) comprising a leading edge (2) and a trailing edge (3) which extend from a hub part (4) to a tip part (5) on the guide blade (1). The guide blade (6) has an additional welding boss (6) on the trailing edge (2) avoiding burn out of the trailing edge (2) during welding process. The invention related also to a stationary cascade (7) for a turbomachinery whereby the stationary cascade (7) is built with inventive guide blades (1).

Description

[0001] The present invention related to a guide blade for a turbomachinery, whereby the guide blade comprising a leading edge and a trailing edge which extend from a hub part to a tip part of the guide blade. The present invention related also to a stationary cascade for a turbomachinery, comprising a hub and a tip ring and a number of guide blades which are welded between the hub and the tip ring, whereby the hub parts of the guide blades are welded at the hub and the tip parts of the guide blades are welded at the tip ring.

[0002] Stationary cascades according to the state of the art, comprising a hub and a tip ring and a number of guide blades. The guide blades are fixed at the hub and the tip ring. To fix the guide blade at the tip ring, the tip ring has a hole which shape is similar to the guide blade profile, so that the guide blade could plug into the hole and fixed by a pin. This solution is probably shown in DE 195 47 653 C2. A disadvantage of such a solution is that for each guide blade an own profiled hole is necessary which make this solution complicate and expensive.

[0003] A cheaper solution is, to fix the guide blade by a welding process between the hub and the tip ring. Due to the very thin thickness of the trailing edge of the guide blade compared to thickness of the hub and the tip ring there is a technical problem during the welding process. The high temperature of the welding process and the thin thickness of the trailing edge lead to a so called "burn out" of the material of the trailing edge which lead in the worst case to a destruction of the guide blade.

[0004] It is object of the present invention to solve aforesaid problems provide a cheaper stationary cascade.

[0005] Aforesaid object is solved by a guide blade to independent claim 1 and a stationary cascade to independent claim 3.

[0006] Advantageous embodiments of the invention, which are used individually or in combination with each other, are subject of the dependent claims, the description and the drawings.

[0007] The inventive guide blade for a turbomachinery, whereby the guide blade comprising a leading edge and a trailing edge which extend from a hub part to a tip part of the guide blade is characterized in that, an additional welding boss is designed on the trailing edge. The welding boss leads to a thickening of the trailing edge, so that the trailing edge is protected for a burn out while welding.

[0008] An embodiment of the guide blade is characterized in that the additional welding boss is arranged only at the hub part and/or tip part of the guide blade. The guide blade will be welded only with the hub part to a hub and the tip part to a tip ring, so that only the welding zone should be thickening. Arranging the welding boss only in these zones the weight of the guide blade could be reduced and the flow over the guide blades will not be disturbed.

[0009] The inventive stationary cascade for a turbomachinery, comprising a hub and a tip ring and a number of guide blades which are welded between the hub and the tip ring, whereby the hub parts of the guide blades are welded at the hub and the tip parts of the guide blades are welded at the tip ring, is characterized in that the guide blades are guide blades according claim 1 or 2.
The welding boss allows by thickening at least the welding zone at the hub part and/or tip part of the guide blade the welding without a risk of burn out and destruction of the trailing edge.

[0010] An embodiment of the stationary cascade is characterized in that the welding boss is almost or completely melted by a welding procedure and protects the shape of the trailing edge from being destroyed by overheating through the welding procedure. The welding boss is dimensioned in that way, that the boss is generally melt by the welding procedure and is just big enough to protect the trailing edge and do not create any additional material which had to be reworked to keep the required designed channel for a media flow. This simplified the manufacturing and reduced the manufacturing time which leads to a cheaper stationary cascade.

[0011] The present invention is further described with respect to the accompanying figures. The figures schematically show:

Fig. 1:

An inventive guide blade

Fig. 2:

An inventive stationary cascade

The same or functionally identical components are cross-figuratively provided with the same reference numbers.

[0012] Figure 1 shows an inventive guide blade 1. The guide blade 1 comprising a leading edge 2 and a trailing edge 3. The leading edge 2 and the trailing edge 3 extend from a hub part 4 to a tip part 5 of the guide blade 1. The guide blade 1 is usually used to build a stationary cascade 7 for a turbomachinery which will show and described in Fig. 2. The stationary cascade 7 comprising a number of guide blades 1. Figure 3 shows only a few of them. The guide blades 1 are circularly arranged at the same distance from each other and welded between a hub 8 and a tip ring 9, whereby the hub parts 4 of the guide blades 1 are welded at the hub 8 and the tip parts 5 of the guide blades 1 are welded at the tip ring 9.

[0013] Due to the extremely thin thickness of the trailing edge 3 there is only very less material at the trailing edge 3. To avoid a burn out of the trailing edge 3 during the welding process based on the difference in the material thickness between the massive hub 8 and massive tip ring 9 with regards to the thin trailing edge 3 of the guide blade 1, additional welding bosses 6 are designed on the trailing edge 3. The additional welding bosses 6 are only designed in the welding zones at the hub part 4 and the tip part 6 of the guide blade 1, so that the media flow will be disturbed as less as possible. In principle the welding bosses 6 could also extend over the whole trailing edge 3.

[0014] The additional material of the welding bosses 6 reduced the difference in material thickness between the massive hub 8 and massive tip ring 9 with regards to the thin trailing edge 3 of the guide blade 1. Therefore, the risk of burn out of the trailing edge 3 during the welding process could avoid. The welding boss 6 is almost or completely melted by the welding procedure. The welding boss 6 is calculated advantageous that it is just big/ massive enough to protect the trailing edge 3 to avoid burn out and do not create any additional material which required a reworking of the welding seam such as grinding or cut off to fulfill the flow requirements in the stationary cascade 7.

[0015] The invention can be used generally for hub part 4 and/ or tip part 5 and is applicable for various types of turbomachinery blades or vanes. The blades or vanes can be generally prismatic, conical, leaned bowed or any combinations. It is not limited at any special type of turbomachinery.

[0016] The inventive guide blade and the inventive stationary cascade allow for the first time a high quality of welded turbine stationary cascades. Thereby the production costs can be reduced considerably.

Claims

1. Guide blade (1) for a turbomachinery, whereby the guide blade (1) comprising a leading edge (2) and a trailing edge (3) which extend from a hub part (4) to a tip part (5) of the guide blade (1)
characterized in
that an additional welding boss (6) is designed on the trailing edge (3).

2. Guide blade (1) according claim 1
characterized in
that the additional welding boss (6) is arranged only at the hub part (4) and/or tip part (5) of the guide blade (1).

3. Stationary cascade (7) for a turbomachinery, comprising a hub (8) and a tip ring (9) and a number of guide blades (1) which are welded between the hub (8) and the tip ring (9), whereby the hub parts (4) of the guide blades (1) are welded at the hub (8) and the tip parts (5) of the guide blades (1) are welded at the tip ring (9),
characterized in
that the guide blades (1) are guide blades (1) according claim 1 or 2.

4. Stationary cascade (7) according claim 3
characterized in
that the welding boss (6) is completely melted by a welding procedure and protect shape of the trailing edge (3) from being destroyed by overheating through the welding procedure.

Drawing