RUNNER FOR A HYDROELECTRIC AXIAL TURBINE OR PUMP

Abstract

A propeller-type runner for a hydraulic turbine or pump has a hub and a plurality of blades. Up to and including two blades are fixed to the hub using bolts. The remaining blades are welded to the hub. Each bolted blade is adjoined by two welded blades.

Claims

1-5. (canceled)

6. A propeller-type runner for a hydraulic turbine or pump, the runner comprising: a hub; a plurality of blades mounted to said hub; said blades including up to two bolted blades affixed to said hub by way of bolts and remaining said blades being welded blades that are welded to said hub; and each said bolted blade being adjoined by two said welded blades.

7. The runner according to claim 6, wherein a total number of said blades is three, and exactly one of said blades is a bolted blade affixed to said hub by way of bolts.

8. The runner according to claim 6, wherein a total number of said blades is four, and exactly one of said blades is a bolted blade affixed to said hub by way of bolts.

9. The runner according to claim 6, wherein a total number of said blades is four, and exactly two of said blades are bolted blades affixed to said hub by way of bolts.

10. The runner according to claim 6, wherein a total number of said blades is more than four, and exactly two of said blades are affixed to said hub by way of bolts and said bolted blades are disposed on opposite sides of said hub.

Description

[0007] The invention will hereinafter be described in conjunction with the appended drawing:

[0008] FIG. 1 is a cross-sectional axial view of a propeller type runner according to the present invention.

[0009] FIG. 1 displays schematically a cross-sectional axial view of a propeller type runner. The hub of the runner is designated by 1. The runner comprises four blades whereas two of the blades are fixed to the hub by welding. One of the fixed blades is designated by 2. The other two blades are construed to be detachable meaning that these blades are of the bolted type. One of the bolted blades is designated by 3. In FIG. 1 the bolted blades are displayed in the detached position as would be the case for shipping the runner. It is clear that the size of the runner in the vertical direction of FIG. 1 is much reduced by dismounting the bolted blades. In many cases it would be even sufficient to construe only one of the blades to be detachable to avoid difficulties during shipment of the runner.

[0010] In FIG. 1 it can also be seen that the mounting flangesthe trunnionsof the bolted blades 3 are relatively large. The size of the hub 1 is not big enough that all of the blades could be made detachable which such large trunnions. Since only two blades 3 are construed to be detachable and the two blades 2 adjoining each bolted blade 3 are welded to the hub 1 there is space on the hub 1 spared and the large trunnions can be accommodated by a relatively small hub 1. Welded blades do not require trunnions. Large trunnions improve the structural stability of hubs with bolted blades. Furthermore large trunnions do not need a sophisticated design and can be produced at low costs.

[0011] FIG. 1 is meant as an example of the invention. Of course the invention is also adoptable to runners having a different number of blades. In any case each of the up to and including two bolted blades 3 have to be adjoined by two blades 2, which are fixed to the hub 1 by welding. It is clear that one of the two adjoining welded blades 2 has to be located on one side of the bolted blade 3 and the other adjoining welded blade 2 has to be located on the other side of the bolted blade 3. This means that a bolted blade 3 does not adjoin another bolted blade 3.

[0012] If there are two bolted blades 3 incorporated in a runner according to the invention, is favorable that the two bolted blades 3 are located on opposite sides of the hub 1 to reduce the size of the runner as much as possible during the transport to the site and to facilitate the balancing of the runner.